PINTO CAR CLUB of AMERICA
Welcome to FordPinto.com, The home of the PCCA => General Help- Ask the Experts... => Topic started by: BrandyMB on March 27, 2015, 11:21:29 PM
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Im working on a 74 Pinto 2.3 for my wife which was stored for 14 years. Only needed a few things to make it roadworthy. Being its a 74 in the kingdom of CA, I removed all the smog stuff and vacuum lines and ran the distributor vacuum advance straight to ported vacuum off the bottom of the carb. Have installed a complete new tuneup kit, points, plugs, condenser, rotor, cap and plugs etc. Problem is, I cannot get it to idle. It is very rough and smooths out if I close down the choke plates or give it a bit of throttle. It acts like it has a vacuum leak at idle but there are no open points, everything is capped off. Ive had two other mechanics look at it and we are all puzzled. Any suggestions will be GREATLY appreciated!
Mark
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if it has power brakes unplug the brake booster vacuum line and plug it up for a moment .. my 80 had a bad booster causing a vacuum leak and a miss at idle on the number 3 or 4 cylinder ..it` been a day or two since i had it ...
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Should run a compression test and leak down test. Do you know why it was parked for 14 years?
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Thanks for the replies! No power brakes for one, and for two, it was parked cuz it belonged to a lady who parked it in her garage and let it sit while she drove her Ford Explorer. Just for grins, Ill do a compression test etc on it.
Mark
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Hi Mark,
I have a 74 with the 2.3 and you might need a little more advance in your distributor, or an adjustment to the mixture screw on the carburator, maybe a quarter to a half turn out.
Best regards,
Dennis
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Well, the manual calls for 6 degrees BTDC and I have it at around 10 or so. The idle mixture screw has no real effect whatsoever.. I wonder it there's something stuck in one of the jets or orifices..?
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On my car the mixture screw has a big effect. You might be right about something in the carb.
Dennis
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Carb issues would be pretty likely. I know if I sat around for 14 years, I'd have crust in my orifices too.
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Carb issues would be pretty likely. I know if I sat around for 14 years, I'd have crust in my orifices too.
Wouldn't we all?!?!?
Dwayne ;D
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Usually when the mixture screw wont cut off the gas it means theres too much getting through in another circuit on the carb. For me its always been a leaky power valve diaphragm thats the first sign its leaking. To test it just take the top half off the carb turn it over press the power valve in, put your thumb over the little hole on the edge and if it stays depressed its ok if it pops back out when you let it go with your thumb over that hole the diaphragm is leaking.
Most likely it is leaking. Might be other issues with the carb, like loading up (dumping gas over into the throat after idling a minute due to the float not set right). All I ever really do to mine is just on the top half.
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Good call Tonij! Another problem is the gas will dry up and leave crud when it not run over time. Crud will not wash out with new gas when started at a later time too. Stuff will turn to concrete over time.
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'The idle mixture screw has no real effect whatsoever.'
The carb has an issue. You MUST get some effect from turning that screw and the indicator there. Provided we are talking the correct screw of course.
No way should one expect a carb sitting that long to work right, oddly some do but most will not. Once the fuel dries up in bowl it takes any rubber parts along with it, they get rock hard and then trying to start carb with new fuel later but not letting car sit at least 48 hrs. to then reinvigorate the rock hard rubber parts then sees them tear or other fault when you start car up. Meaning power valve and accel pump diaphragms are most likely junk now. The dried up fuel often clogs small idle feed ports as well and then you often physically must clear them back out, the varnish can be hard as rock and simply setting in fuel will not dissolve that back out. Aforementioned problems even worse if car used ethanol laced fuel before it was allowed to sit.
First thing I do on any car coming back up after a long sit like that is go through the carb. I won't lift a finger to start it till done.
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That power valve diaphragm will affect the idle because when they leak the vacuum at idle cant hold it closed and you get enrichment you dont need at idle. The car will run pretty well at high speeds though.
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Absolutely and will be rich enough that mixture needle will not cut off enough fuel to lean it back out. The PV often is worth up to ten jet numbers in what it contribute to fuel, WAY too much for idle only.
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I appreciate all the replies from you fine folks out there. I will have the carb redone, I have a kit for it. Funny thing is though, when the motor is warmed up and the choke is wide open, it idles like crap but if I close it down some by hand the motor smooths out and speeds up. It acts like almost a vacuum leak at idle. And I looked at EVERYTHING! Nowhere to leak.
Mark
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Then that says possible clog in idle fuel passage....... .............. ...And why the mixture screw has no effect. You could simply pop out the idle fuel jets that screw into top sides of carb at each barrel and clean them to save the carb job maybe, but some have at least one of the jets made non-removeable so as to stop emission settings tampering. Several places those clogs can occur usually at the smallest restrictions in the passage as capillary action tends to keep them covered with a fuel bubble that then cooks to a plug with turned off engine heat. Why carb jets tend to be one of the first places to clog. Easiest for trash to plug the smallest hole as well.
The mixture screw only has an effect over a very small range, if the carb error makes mixture way rich or lean the screw then appears to quit working, it cannot affect the range enough with its' limited action.
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Any update on this problem?
I know this sounds basic but it has happened to me more than once. Before you tried to start the car by any chance did you buy a couple new line filters and one for the carb inlet?
What i have learned (done) on cars that sit for a length of time is to get new rubber fuel line to replace the old stuff. i will slice into the line before the pump and place a filter there, then i will slice in a new one after the pump, then replace the carb inlet filter.
reason being this will (should) eliminate any rust that is in the old metal gas and if water has condensed in the lines.
It is a pain to run the line and filters but it will work.
on my car when i got it running i have 1 that is plumbed just out of the tank, then 1 screwed into the electric pump, these 2 are about 1 foot from the tank. next i have 1 that is after the metal line before the carb, then a last one at the carb inlet. The one that is after the line before the carb catches tons of rust from the line (i never replaced it when i got the car running.
food for thought. cheers
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I appreciate the reply and advice, Starsky. I probably wont be able to get back on the car till next week. I had another small project get in the way, I picked up a 1966 pinball machine for my shop and am finishing up getting it all operational (I was an arcade mechanic for some earlier life years). Ill bet the carb is all fulla junk..
Happy Easter all!
Mark
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I had the same bad idle smoothed out when driving. I went problem all the checks for vacuum leaks, tune up etc. Ran like one cylinder was dead. It turned out to be blown head gasket.
Good luck, Bob
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'... i will slice in a new one after the pump, then replace the carb inlet filter.'
An excellent idea and I do it too. All those years can fill the tank with fine powder rust that goes right through the tank inlet sock and then stacks up in the carb bowl to make trouble. The super small carb inlet filter is garbage there and clogs in a minute, I use the biggest paper type filter I can get patched into the line between pump and carb. Preferably clear so I can see how much crap is in it. If car brought up after a long downtime you may end up changing that filter say twice in the first month of operating the car. After that the crud will drop off. Ethanol use if they use it where you are makes that rust issue MUCH worse.
Look at modern cars now and how big the filters are, they are ten times bigger than they used to be, there's a reason for that.......... ....
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Well i finally got back on it. I took the top off the carb and there was all of maybe 1/4 inch of fuel in the float bowl. I put a kit into the carb, added another filter (there was some very fine crap in the bottom of the bowl), cleaned out all the passages and jets. Saw no clogs. Put back together, the float was set at the right level according to the kit, and it still runs exactly the same. I cannot find a decel valve anywhere on the motor. And I looked everywhere. damn. What next?
Mark
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Well i finally got back on it. I took the top off the carb and there was all of maybe 1/4 inch of fuel in the float bowl. I put a kit into the carb, added another filter (there was some very fine crap in the bottom of the bowl), cleaned out all the passages and jets. Saw no clogs. Put back together, the float was set at the right level according to the kit, and it still runs exactly the same. I cannot find a decel valve anywhere on the motor. And I looked everywhere. damn. What next?
Mark
Let's ask a question about how the intake is working for you. Have you checked manifold vacuum at the area under the Butterflies of the carb? With a dial gauge the reading should be 11-17 Hg of vacuum with a steady needle at idle rpm. It should drop when you crack open the throttle as vacuum is highest with the butterflies nearly closed at idle. If you can't get at least 11 inches of vacuum at idle or the needle jumps back and forth, you have a serious vacuum leak or a intake valve seating problem in one or more cylinders. Adding choke to the air flow is only masking a bigger problem as it does appear a lean issue is at hand.
I don't think Ford installed Decel valves on the 2.3L in 74, only the early 74 with 2.0L motors seemed to have them, if equipped they could leak and disturb mixture beneath the butterflies.
Pintosopher, mixing a 14 to 1 without ethanol in my beverages ;D
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Have you checked the compression yet?
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Pintosopher: It has 15" at idle, cold. If i open the choke more than maybe 1/2" at that point, it just dies.
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Pintosopher: It has 15" at idle, cold. If i open the choke more than maybe 1/2" at that point, it just dies.
Within Range, but only will idle with Choke closed? Steady 15 inches no flutter? Lowest Rpms while you can keep it running?
Assuming that the engine has a good leakdown check done , good within spec Compression in all cylinders, Crank, Cam and Distributor properly lined up , We're then looking for either carb or ignition issues. It always boils down to verifying mechanical , then spark, then fuel mixture. Any system or component that works within these parameters can mess it up. Rare situations like a cracked head do occur and would be difficult to find without specialized equipment or disassembly.
I seem to recall finding a cracked EGR block on my wife's old 2.3L 74. and nothing would work up until I fixed that first. Huge vacuum leak under the carb then. Check that if you have a EGR.
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sounds good. ill pull it off and see.
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well i pulled the egr valve off and made a block plate and put it on. No change.
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I think you still may want to replace that power valve diaphragm but it may not be your whole problem. One place known for vacuum leaks on these cars is the mounting bolts at the base of the carb check to see if theyre tight they somehow work their way loose.
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Ok. I pulled the carb and gave it to a friend for a complete going thru. He did and didnt find anything serious except for some dirt. I put it back on and no change. still wont idle once the choke opens. I cant think of anything else. New ignitions components all the way around and set correctly, new timing belt, 14" vacuum at base of carb. dont know what else to do. Got no more hair to pull out. What could i be missing..?
mark
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And so the head banging into the brick wall begins........ ...
If the carb mixture screws still have no effect you haven't cleaned carb yet. Or a vacuum leak not found. Or dead fuel pressure, you mention low level in fuel bowl, if car was just running prior to that teardown a big indicator there.
Compression test first, cars usually sit 14 years because something wrong with them (sound familiar?). To make sure you're not wasting time on anything you do. If not done you can spend the next solid month on work and still be in the same boat.
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http://www.ihpartsamerica.com/forums/carb-tech/3153-weber-carb-rebuild.html
This picture shows using a vacuum pump to test the power valve diaphram. If you dont have one, just push the valve in, hold your finger over the hole where they have the vacuum plugged into, and let go of the valve.If it stays down its ok if it doesnt the diaphram is leaking.
If you cant see where that hole under the top half is, listen as you push the power valve in for air coming out from it.
That test was ne I read in Petersons guide to the Pinto and I always do it when I get the no shut of from t he mixture screw issue.Its always been the power valve diaphram. Do the test yourself.
But 14 inches is pretty low for idle vacuum. Have you got the timing set? The compression test is a good idea for sure.
Another thing is, does your carb have foam floats or hollow plastic? If its foam you need to weigh it to see if its soaked up anything and heavier than it should be.If its the hollow one, you can throw it in a bucket of water or gas and see if it floats or makes bubbles if you push it under. They do get holes in them,I found an extra not long ago I was going to save until I found out it had a hole :(
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Thanks for the reply ToniJ! I already have the exact same Rhino Ramps in the link you sent me.. Resend me the correct link please! LOL! Regardless, the power valve is new. I just had a kit put in the carb by a friend who builds racing carbs and knows his stuff. The floats are the plastic type and are fine. I do have a question.. I put a new timing belt in it and made sure the timing marks on the cam and crank were lined up properly. The other shaft got turned accidentally, but the only thing I can see that did was turn the distributor setting out of whack. I put it back to the position where the distributor was placed where I could get the timing right again. Book called for 6BTDC. Also I have a plate over the EGR mount and all vacuum ports have caps over them.
Mark
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Thanks for the reply ToniJ! I already have the exact same Rhino Ramps in the link you sent me.. Resend me the correct link please! LOL! Regardless, the power valve is new. I just had a kit put in the carb by a friend who builds racing carbs and knows his stuff. The floats are the plastic type and are fine. I do have a question.. I put a new timing belt in it and made sure the timing marks on the cam and crank were lined up properly. The other shaft got turned accidentally, but the only thing I can see that did was turn the distributor setting out of whack. I put it back to the position where the distributor was placed where I could get the timing right again. Book called for 6BTDC. Also I have a plate over the EGR mount and all vacuum ports have caps over them.
Mark
I've seen no mention as to whether this car has had the head rebuilt or been apart to replace a head gasket and had the head resurfaced too. I do see that you have moved the distributor drive sprocket and reset it. Keep in Mind , if these three marks are not synched (because of the head possibly being resurfaced there is cause for concern here) it won't idle properly. having the engine marks on the crank pulley and cam sprocket in exact alignment is key to any adjustment (whether it be ignition timing, or mixture adjustment).
If you suspect that any engine work has been done, it's time to check this one off the list. This is relevant because those marks can be off enough to get the engine unable to run well at all at idle. Bad keyway indexing from the Factory has led to offset keys and even the much desired adjustable cam sprockets. This is a critical thing to check first before you go off on any more Fuel related adventures.
How do I know? Just ask anyone here that races a OHC engine of any brand, especially an old Ford. There's a whole tuning philosophy to camshaft advance and it does have an impact , even on stock motors.
A degree check of this system is in order.
Pintosopher, as much as good timing will allow. ;)
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Funny thing is, there was no mark on the third shaft gear and believe me I looked. The car idled fine before I changed the timing belt and removed the smog crap. I also checked the timing marks before I pulled the ratty old belt. All good info, Mr Pintosoher. I dont think it would have idled well before all this if there was an issue with the head etc..?
Mark
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There is NO third shaft mark, setting the timing correctly and engine running at all means that is OK. Assuming timing set at BTDC not ATDC. A third shaft mark would actually be detrimental, you can put the shaft anywhere you want as long as the distributor is moved along with it to work right. Assuming correct point gap (points! HILARIOUS!) as well, gapping by hand is insane, use a dwell meter.
14 inches of idle vacuum IS low, I expect 18-20 on a normal good running engine.
IF car truly idled well before the belt and smog pulled then it is clear you messed up on pulling the smog. Several ways you can have a vacuum leak there for sure. That mixture screw HAS to work or you are p-ssing in the wind.
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There is NO third shaft mark, setting the timing correctly and engine running at all means that is OK. Assuming timing set at BTDC not ATDC. A third shaft mark would actually be detrimental, you can put the shaft anywhere you want as long as the distributor is moved along with it to work right. Assuming correct point gap (points! HILARIOUS!) as well, gapping by hand is insane, use a dwell meter.
14 inches of idle vacuum IS low, I expect 18-20 on a normal good running engine.
IF car truly idled well before the belt and smog pulled then it is clear you messed up on pulling the smog. Several ways you can have a vacuum leak there for sure. That mixture screw HAS to work or you are p-ssing in the wind.
Actually the invisible "third mark " is having the distributor rotor pointing at the #1 wire location on the distributor cap, while the other two marks are aligned at TDC on the Compression stroke. The movement of the distributor body to set the Ignition timing must be roughly in the center of allowable range of movement. If the Belt is properly tensioned with the marks on the correct stroke, (cam, Crank and Distributor rotor) then this should rule out anything mechanical( timing wise) except a head that has been shaved , thus the marks would be accurate. Beyond this, a porosity issue with the intake manifold, carb body, gasket sealing between the carb and head, or any possible leakage from any of the vacuum connections that were removed or capped. After this, a swapped carb would give an indication that all is in the original carb if it corrects the problem.
The idle manifold vacuum should be higher but if it's steady, it may be pointing back at a leaking component. Achieving a higher manifold vacuum would be a better starting point.
Pintosopher, looking for the elusive PZEV gnome every day when fumes arise. ;)
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Well Gentlemen, then I have all the components, ignition related, correct. All ignition parts are new, points set right too etc. I had the carb redone by a friend who builds race stuff and knows what he's doing, and had the motor looked over by him and another race guy I know and no one can see where a vac leak could come from. We sprayed stuff everywhere and the idle never increased or otherwise indicated finding a vac leak. When I put the carb back on, it started right up and idled so nice.. until the motor warmed up and the choke opened, then it went back to non-idle. I would put all the smog crap back on it if I had a hose diagram.. which seems to be non-available. Theres where the prob must lie. But every car Ive ever had in my entire life ran better with the smog crap plugged or removed. Im at a total loss.
Mark
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Well Gentlemen, then I have all the components, ignition related, correct. All ignition parts are new, points set right too etc. I had the carb redone by a friend who builds race stuff and knows what he's doing, and had the motor looked over by him and another race guy I know and no one can see where a vac leak could come from. We sprayed stuff everywhere and the idle never increased or otherwise indicated finding a vac leak. When I put the carb back on, it started right up and idled so nice.. until the motor warmed up and the choke opened, then it went back to non-idle. I would put all the smog crap back on it if I had a hose diagram.. which seems to be non-available. Theres where the prob must lie. But every car Ive ever had in my entire life ran better with the smog crap plugged or removed. Im at a total loss.
Mark
Something is being masked here by the Choke butterflies being nearly closed. If the fuel supply to the bowl is adequate, and fuel pressure and pump output to the carb consistent, then a rich mixture is masking a lean condition . Even with all of the Smog devices capped or removed, it should idle at warm temp and the mixture screw have an effect.
Out on a Limb here, have you run a Cold AND Hot Compression test, and the same with a leakdown test? If the expansion of the head is exposing a weak area of the gasket that coincides with the Choke (water temp controlled) you may have a temperature related head gasket failure causing a lean Hot condition. This doesn't mean that you'll find it by looking for anti freeze in the Oil, as it can leak to the outside of any part of the head.
Given that resurrecting an engine that was sitting that many years unused, can cause all kinds of failures when restarted when you start the thermal cycling of the parts. I've had a vintage Porsche run fine until it dropped two intake valve seats after a few runs while tuning it. It was a known issue amongst the Experts and should have been dealt with before reviving the car after 20 years idle. Unleaded gas only made it worse, even with a lead additive in the fuel. I was cautious when getting that one ready too, and it still bit me.
There's more to be checked on this one before you dig further into the carb.
My Bucket of Cents is running low here, more pennies needed :o
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THAT sounds like a distinct possibility. Ill do them tests next time im out at the shop. Wife is sick amd Im playin nanny for the moment lol.
Mark
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THAT sounds like a distinct possibility. Ill do them tests next time im out at the shop. Wife is sick amd Im playin nanny for the moment lol.
Mark
I'm in the same boat with my wife right now, Super nanny! Can't get back to my VW GTI ,chasin Evap System ghosts lol! :D
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You know, if I could find a diagram of the smog stuff, id put it all back on just to see..
Yeah, I have a 65 GTO and a 80 Vette that need my attention also and they're just gathering dust. But this little uncomplicated Pinto is making me pull out the rest of my hair, and I'm bald already..
Mark
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Waste of time, all that's needed there is to plug the vacuum sources you unplugged at that time and the cars run forever with no smog, I did an MII '74 model same engine and it ran forever, took a 6 inch hailstone storm to take it off the streets in '95. No magic there, I'd bet a million on carb internal error or fuel supply issues there. Why all the vac leak testing showed nothing but still a hundred other places you can error there. Your race guys should well know that, I built plenty of race carbs and motors myself. That little carb there often stymies race carb guys as Holley carbs are so simple that 1st graders understand them, not so that carb.
And, IF car was running fine before then why did we mess with the carb to begin with? FYI, I have heard that 'it ran fine before I...' line so many times it goes in one ear and out the other on a 6 lane freeway, often it turns out to be totally false. NO INSULT INTENDED AT ALL BUT when one says that they lock themselves into not weeding out all other choices by the people helping and often results in the poster NEVER getting the problem fixed. I've seen it a 100+ times and why most GOOD repair guys often ignore everything a person says about a car and previous conditions so he can start with a clean slate to easily figure out the problem. Sorry, but often the ONLY way they get fixed.
And why compression test keeps getting mentioned..... ...........the car is a '74 with no induction hardened valve seats, if the 14 year timeline is right then it could have been driven for years after all fuel went from low lead to true 100% unleaded around '93 or so and the valve seats could be dead as a doornail to have the car not run right at all. The same MII I reference above began to have severe valve problems every 10,000 miles after the fuel changed. Another valve job and back to running fine until they die again. Idle going to crap is what shows up first to most novices, power will drop off before that but low enough amount that most will not notice and claim 'it runs fine', sound familiar?
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No insult taken, my friend. I know exactly where youre coming from. Im retired Systems Analyst and I used to go out on network/computer issues and ALWAYS started over from the beginning regardless what the user told me he/she did. I tend then to agree with you too. The engine never seemed to have the getup and go I would have expected it to have, when I did say it was running right. Smog systems (here in CA) always dog a motor down so I removed the AIR system right away. Dont need to be driving that pump. Friends suggested I ditch the rest so I did. Now that the wife is getting better I can spend a ittle more time messing with the car. I intend to do compression checks and I have a bud who has a leak-down tester. Also I would just love to ditch that complicated carb and install a simple straight forward one. Any suggestions on a not break the bank bolt on carb? Oh this is such fun. I have a 65 GTO, 80 Vette and a 75 CJ5 and rebuilding them never gave me 1/10 the headache this Pinto has!
Mark
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Original carb is actually the best one if you do not want to launch into rejetting and things like that. The Ford 2 barrel 2100/2150 used on the bigger cars often used but you must set up the carb yourself. And if you can't find the problem here in carb, then same problems with that one although less passage issues with clogging there. This carb is simple as well, just not many used to the ways it does the same things all carbs do. I grew to like it as I was very familiar with it but then I've done carbs all my life so none of them are an issue.
If wanting to go to the other carb Dick here onsite could probably help with that.
For sure yank the small entry filter if keeping this one (5200) and patch in a bigger inline one with rubber hose on both ends as adapters. That small filter can clog in five minutes of running if they use ethanol in your area and your steel tank will be full if superfine powder rust from it. You need to pull the idle feed restrictions that both screw into the carb top and positively make sure the very small port in them is fully open. IIRC, the actual jet there simply inserts inside the outer screw cover that threads into the carb top. Jet has holes through the sides and one small one right down the middle. Thinking you can pull those without removing carb, at least the driver side one. Those feed the idle fuel.
My younger brother was a national network systems analyst for McKesson-HBOC before they cut back all the 'overpaid' help, they replaced him with 3 other people and still lost their butts by letting him go. I probably picked up some of my outlook from him as well.
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Darn how did I do that sorry
http://www.ihpartsamerica.com/forums/carb-tech/3153-weber-carb-rebuild.html
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Post #6 in that thread clearly shows one of the idle feed restrictors, the brass colored screw at the top. It is really just a holder, the restrictor is pressed inside it.
Power valve vacuum leak issues can be problematic, while a greater leak will lean out the idle, a smaller one will richen the idle when the valve then slowly moves down to open the power valve, like adding at least five sizes larger main jet and the engine goes rich even with a vacuum leak since at idle the main jets are unused. As the vacuum leak gets bigger though it will overwhelm the richness to then go lean. A see-saw effect there.
Knowing how to take apart and reassemble a carb is not the same as knowing what every last single port and hole does in fine detail, and how to mod any of them when the carb does not do what you want.......... ......... big difference there. Anybody can change jets or power valves, it's when you start drilling holes bigger or more of them and things like that you'd best know what you are doing.
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Am I wrong in thinking that mixture screw pretty much has to be able to cut off the gas/air mixture unless its the power valve lettting more gas through? Thats what I was told a long time ago by the guy who rebuilt my motor. The description on this site makes me think its true as well.
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all my experience says i agree...
"...[size=78%]You need to pull the idle feed restrictions that both screw into the carb top and positively make sure the very small port in them is fully open. IIRC, the actual jet there simply inserts inside the outer screw cover that threads into the carb top. Jet has holes through the sides and one small one right down the middle. Thinking you can pull those without removing carb, at least the driver side one. Those feed the idle fuel.[/size][/size][size=78%] [/size]
[/size]
[/size][size=78%]these do have a lot to do with how [/size]the[size=78%] car can run. have had to start from scratch, bone stock, many times in the past to get BACK to a baseline to, once again, begin a diagnosis[/size][size=78%]
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Well, it idles! I took off the egr plate and cleaned and changed the gaskets, also took the carb back apart and went thru it with a magnifying glass. I took everything back apart again and blew out every passage and place fuel could go. It appears that there may have been a little piece of crap in the idle jet. I couldnt blow thru it nut anyway, I put it all back together and it idles and the mixture screw has some effect.
So I took it out for a ride and I have a new strange issue. It doesnt seem to be getting enough fuel maybe. What was odd, I push on the gas and it gets a some nice power while the gas pedal is moving down, like the accelerator pump is feeding it, then it tapers off if I hold the gas steady. I can pump the gas pedal and it gets nice shots of power as I do it. lmao! It runs kinda flat though until I floor it and the other barrel opens up and it picks up nicely.
What may I have screwed up??
Mark
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Making some headway at last I see. Sometimes you never see the offending clog but you'll know when it is gone. Yes, now you know about the idle passages, may be looking at power valve issue now if it only messes up at demand for more power.
If you get to the problem but then punching gas pedal to work accel pump makes it better then most likely lean without the pump shot and possibly a power valve issue. Under the valve itself that screws into bottom of fuel bowl is another small restriction in the sideways passage that because of being so low often clogs to make power valve not work even if the piston and valve moving up and down like supposed to. Sort of the main jet for the power system if you will.
Yes on earlier non-smog carbs the idle mixture screw should totally kill the engine when screwed shut, once past like '78 or so though they may only make engine slow down but not die, the later even leaner carb settings killed some of the screws' effect but not all, you should be able to get some at least slight effect both too far out and too far in, some won't show much at too far out though as they were not set overly rich any longer like they used to be. The engineers were narrowing the tuning envelope there since so many mess with things they should not be touching, the EPAs' 'tampering' thing. Why they began to get limiter caps.
Kicking secondary open to make it better seems to point at the power valve. The valve feeds the primary only and is part of the main systems' fuel at full power, with it off like downjetting 5-10 steps of main jet depending on the carb.
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All we can do is make wild A#@ guesses but heres a scenario I had.
If the vacuum is too low to hold the power valve actuattor up off the valve, and too much fuel is getting through so that the idle screw cant kill it, and it was somehow all fiddled to make the car idle that way, then theres no power enrichment possible as the actuator would already be holding the valve open.
Or if theres a vacuum leak inside the carb ie ruptured pv diaphragm or leaking where the top meets the bottom of the carb. Vacuum is supplied through the bottom casting to that channel that carries it to the pv diaphragm.
The first thing I would do still is take the top half off turn it over push the actuator in, put my thmb over that hole ( see picture 8 where its marked with a dark stain) and if the actuator doesnt stay down until you remove your finger or thumb from over that hole, the diaphragm is ruptured or not sealed right inside its housing.
I got a kit for my carb and it did come with two different diaphragms and I know theres a long and a short sized actuator.
Also, on the diaghragm that came with that kit, the base shape of the diaphragm was a little off and took carefull trimming or installation I cant remember exactly but I think it had something to do with the area around where the screws went in.
Now another time I needed a diaphragm for the choke pulloff, went to this carb shop that everyone touts locally. I bought the diaphragm put it in ran great a few days later it didnt. I took it out it had stretched. I looked it over and it seemed to be a lot thinner material and didnt have the threads or fibers in the rubber. Maybe it worked on a Chevette but not on a Pinto.
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Toni,
thank you and all of you for your replies. Im in the middle of a job so I cant write much at the moment, but where is picture 8?
Mark
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I shouldve said the picture in post 8 here
http://www.ihpartsamerica.com/forums/carb-tech/3153-weber-carb-rebuild.html
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' The first thing I would do still is take the top half off turn it over push the actuator in, put my thmb over that hole ( see picture 8 where its marked with a dark stain) and if the actuator doesnt stay down until you remove your finger or thumb from over that hole, the diaphragm is ruptured or not sealed right inside its housing.'
X2, I do the same.
Take note when swapping different year parts that the later PV is metered out rather than all on or off with no in between, you CAN swap some of those parts but the vacuum source changes location, they while going to the metered one were setting up the engineering for the true feedback carb which at first used the PV system remnants to modify the carb signal pull to the main jets electronically . The later type PV will be on carbs with the different top cover that kicks out a new notch in the aircleaner base, the two bases do not interchange. The power valve itself will have a gradual metering rod type stem as well instead of the dead flat cutoff part of the poppet there. The spring rates are different too, one has to move slowly, the other moves quick when needed. The later top has the advantage of a setting screw in it to then be able to exactly set the power valve top vacuum piston too. So you can set the exact timing of the come on of the metering. I mixed and matched a few of those parts to pretty good result there for a while.
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Im about to go out to my shop and pull the lid and check out the PV as you folks have recommended. The PV is new in the crtb when it was kitted her the other week, but may be on incorrectly or vacuum leaking. Ill also check the passage under the PV valve in the bottom of the carb.
Lol its almost getting to the point for me to just up and buy another carb for it and leave the last two hairs in my head not pulled out..!
Mark
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I just pulled the top and the PV is perfect and so is the valve in the bottom of the bowl. I pulled out the main jets and they say 35 and 42. Would those be right? I can't seem anything else of note..
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Oh by the way, now when I screw the idle mixture in, it kills the motor.
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Is the vacuum idling still 14 inches? I wonder if thats enough to hold the pv actuator in. Do you have a vacuum pump like a mightyvac?
The timing is verified?
You can set the mixture with your vacuum gauge watch the vacuum as you adjust the mixture screw and try to get it to where the vacuum reading doesnt drift up and down.
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15 inches is enough to keep it open. with my mityvac only took about 5 to pull it in i put it back together and drove the car this aft. runs better than before. ill do some more fine tuning tomorrow and see if i can get it beter. thanks!
Mark
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Usually set to open under 10, like 8 or so.
Old tuning half-rule there, you pick a number at half the idle vacuum for power valve if you have choices of them like Holley, which uses 8.5 in most of their stock replacement stuff.