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Offline browniecat

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stock Bobcat plagued by Pinging...
« on: December 01, 2019, 08:27:02 PM »
Hey PintoPeeps.... Happy December from NYC..

Need your counsel..if anybody has an idea.  Have very nice 32K original '80 Bobcat hatchback (2.3l 4 cyl.), and she garners attention WHEREVER we go!!  (It's pretty startling...wh en we're out on the highway, somebody gives me thumbs up every half hour, easily!)

Bobbielou is plagued with pre-ignition.  Back when it was warm, I blocked off the EGR which improved anemic performance considerably.  But thereafter, despite Premium fuel, car will almost always pre-ignite on hard accel.  I have fooled and fooled with the timing, and I have this problem even with timing set at the spec of 18BTDC........ ..If I retard further, the poor girl really runs like crap.  I have lately been running cooler plugs to try to overcome this, but no luck.  (General notes: the timing belt is new as of 8K ago, and I've verified my crank/cam index marks are correctly aligned)  More recently, I've started adding a little octane boost WITH 93 octane fuel, which STILL doesn't entirely eliminate the ping (seems like this should be absurdly unnecessary)!

Anybody experience similar after EGR elimination?  My next moves are lower temp. thermostat.... ..  Any ideas, Kids??  Really hate to go back to an EGR set-up...but...

ALSO -- I have an old Buick that had a similar issue, and soon as I went to a higher pressure rad cap, problem went away, never to return.  Think I can safely use a 16lb. cap on Bobcat (13 is the stock)?

Thanks in advance for any input, guys....have a great week..

David H.


Offline TIGGER

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Re: stock Bobcat plagued by Pinging...
« Reply #1 on: December 03, 2019, 01:19:13 PM »
I would check to make sure the timing belt is set properly.  I got a Honda civic a few years back from a buddy.  It pinged like crazy under load.  I adjusted the timing as much as I could and it did not help much.  When I fixed the crank seal oil leak I had I figured I would put a new timing belt in it and I noticed that the person before me did not set the marks properly before they installed the timing belt.  It was off a few teeth.  I set it proper and no more pinging and the car ran so much better.  Good luck to you
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Offline browniecat

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Re: stock Bobcat plagued by Pinging...
« Reply #2 on: December 03, 2019, 04:11:37 PM »
hey Brotha...

Thanks for replying.  I doubt very much it's off at all, but a few people have suggested I re-check it yet again...so I may get to it soon. The car seems to run generally well, apart from the too-frequent pinging.  Really maddening.

cheers!

Offline pinto_one

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Re: stock Bobcat plagued by Pinging...
« Reply #3 on: December 04, 2019, 07:34:32 AM »
The key word is that you disconected the EGR valve ,  and yes most cars of that time will ping when you do , the reason is the exhaust gas does slow down the burn when the EGR valve is open , but now you have a timing to load problem , you can mask the problem with a few tricks and get rid of the ping , learned this when I worked at a ford stealership back in the 70s when al this emissions crap was being piled on the cars with miles of vacume lines and tees to tie them into a holy mess ,  the first you can try is to remove the line from the distribtor and find a allen wrench (or hex key) that just fits in to vacume advance can , you may have to try a few to find the one that fits , there is a screw inside the adjust the spring inside , from memory I would try one complete turn counter clockwise , mark it just in case youmay have to go the other way , no more than two turns max form your starting point , if that gets rid of the ping great , but if you still have just a trace the next thing you will have to rejet the carb , the bad news is no one supports the carb anymore , so its almost imposable , the only other option is to swap the carb with a 74 to 76 year carb , they ran a tad richer than the one you have now , that also will cover up the ping and give you a few more HP , why , well the newer 78 up carbs had less CFM than the older ones , hope this helps you , I got rid of my ping / fuel problem when I went to EFI , later Blaine
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Offline 71pintoracer

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Re: stock Bobcat plagued by Pinging...
« Reply #4 on: December 04, 2019, 11:05:25 AM »
Exactly right. Years ago l bought a 79 F150 with a 300 six. That thing rattled like a can of marbles! l adjusted the EGR flow and fixed it. Why would you want to unhook the EGR anyway?
If you don't have time to do it right, when will you have time to do it over?

Offline browniecat

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Re: stock Bobcat plagued by Pinging...
« Reply #5 on: December 04, 2019, 05:29:42 PM »
Thank-you, Blaine...!  (esp. liked the Ford Stealership part)

Great suggestion.... and...ummm...I confess I had NO IDEA that the advance was adjustable that way, but I will definitely give that a shot!  (I guess that's similar to adjusting a vac-modulator valve on a trans...so would totally make sense)  So...you've edumacated me today.

I blocked the EGR off because the valve was defective and not completely closing, I had pronounced hesitation; maybe I should've just replaced the darn thing.  But here we are.

So thanks again...let ya know what happens.  The other question there in orig post: any reason I shouldn't use a 16lb rad cap?

Cheerz

ps...reposting my photo, 'cause it was mislabeled as a '78; it's an '80

Offline nnn0wqk

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Re: stock Bobcat plagued by Pinging...
« Reply #6 on: December 09, 2019, 01:40:53 AM »
Adjusting the vacuum advance may not be the total answer either. Keep in mind under heavy acceleration that you really do not have that much vacuum so not much vacuum advance. Now under light load conditions than you will see the vacuum advance come into play. I would start checking what your advance curve is. Most gas engines rule of thumb will be around 40 degrees total advance. Fords of the day would some times approach 50 degrees and they could get away with it if EGR was working.  In practice EGR lowers peak compression because you are getting some exhaust back into the cylinder. Takes up space but does nothing for combustion. Under full load conditions you loose EGR flow and vacuum advance or most of it because you also loose vacuum. So what ever power the engine will produce WOT should be equal EGR or not. The issue is usually the ping under light load and sudden acceleration until the vacuum falls off. So you may have to play with the centrifugal advance cutting it back some and giving it actually more vacuum advance to keep the same total advance. Or get the EGR system back into proper working condition. From personal experience on my 2.3 the EGR spacer plate under the carb plugs with carbon about every 75-80k miles. The other thing is regular fuel of the late 70's was closer to 90 91 octane where now at least in my neck of the woods is 87 plus now most places are not selling 100 per cent dino juice. That also plays into the equation on how these engines respond.

Different engines and application but I have 2 1974 International Harvester 1600 trucks with the 345 engine. Both engines are stock and total advance hits about 32 degrees. That was not a real high compression engine in the day. They are EGR equipped with Holley 2 barrel carbs. Yes they run on 87 octane 10 percent regular fuel, however they will pull the hills 1/2 gear faster if I feed them 91 octane non ethanol. That is pulling 26K gross loads. Have no idea if fuel economy goes up or not and at around 5 mpg not sure it makes that much difference. The point is the fuels we have today are not yesterdays fuel so keep that in mind when your engineering your car. My experience is the ethanol does not burn like pure fuel. BTU's come into play. Let us know what you end up doing to make things work for you. Helps others in the future with their issues.

Offline browniecat

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Re: stock Bobcat plagued by Pinging...
« Reply #7 on: December 10, 2019, 11:42:30 AM »
yo nnn0wqk...!!

Thanks so much for your input....much appreciate all the responses because it's really givin' me an education about this....

Right there with you on today's crappy fuels!!  In upstate NY we have Steward's non-ethanol 91oct available (alas, not in NYC) which my '66 Buick V6 Special LOVES.  Curiously, I've burned this in the Bobcat, and my recollection is She actually then pinged a little worse, even.  But I have to try it again to verify that.

For the moment, I'm sort of pumped to try Blaine's suggestion on adjustment of the advance dashpot...when ever I can get to it.  I do plan to try a lower temp thermostat, my rationale being that blocking off EGR will have raised head temp, generally.  (or am I wrong on that??)  The goal being, to bring temp down as much as poss...

It's entirely possible that I'll wind up trying a new EGR valve if the prob persists, but I hope I don't have to.  Other than the too-occasional pinging, Bobbie's performance has been maybe 20% livelier with EGR blocked.  So we'll see.

Yes, I'll keep you all posted, gents.  Cheers!!

Offline Wittsend

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Re: stock Bobcat plagued by Pinging...
« Reply #8 on: December 10, 2019, 01:41:43 PM »
Combustion chamber deposits can also increase pinging (and elevate NOX if smog testing is important).  Years ago I had a Mazda 323 and even with a new CAT I had rather elevated NOX.  Four years later I trickled distilled water through the intake and also used a can of Seafoam.  The NOX was lower than it had been with the new CAT. The water process is tricky and I had to replace the oil immediately but maybe in your case Seafoam might help?

Offline 71pintoracer

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Re: stock Bobcat plagued by Pinging...
« Reply #9 on: December 10, 2019, 04:16:56 PM »
Did the water treatment many times back in the day....the cold water would hit the carbon and break it up and spit it out of the exhaust. Can't really do that now because of the cat. Ford used to make a product called carb tune-up, maybe still do but anything like that will work. What l do is crank the idle up so the engine doesn't stall, pull a small vacuum hose off and SLOWLY ingest it into the combustion chamber, when the can is empty shut the engine off and let it sit overnight. When you fire it in the morning it's going to smoke like a train!! But the carbon will be gone! Drive it like you stole it for a few miles and the smoke will clear up.
If you don't have time to do it right, when will you have time to do it over?

Offline browniecat

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Re: stock Bobcat plagued by Pinging...
« Reply #10 on: December 11, 2019, 09:21:03 PM »
well, Yeah the olde water treatment in the carb, etc...

I've actually tried that on the Bobcat back a few months ago. Twice.  Either I need to do a cpl more times or there just wasn't much buildup, 'cause I saw hardly any satisfying smoke to speak of.  The Cat's been removed on this old girl, by the by...

I never heard of the Seafoam method, but how about this one, guys..?   My long-time retired Buick mechanic-friend (he's now about 80) said back in the '60s some guys would often run (I assume not TOO much at one time!!) BRAKE FLUID down the carburetor a de-carboning process.  Can't remember if he said they mixed it with water, but...sort of intrigued to try it...teehee.

Cheers, everyone..

Offline 71pintoracer

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Re: stock Bobcat plagued by Pinging...
« Reply #11 on: Yesterday at 11:18:27 AM »
l'm sure anything that will dissolve carbon will work. The vacuum hose method works best because the chemical sits on top of the pistons overnight. Just put it in very slowly so the engine doesn't hydrolock.
If you don't have time to do it right, when will you have time to do it over?