Having trouble with my 74, had trouble with it since ive had it. Have to rev it and hold it for several minutes until it warms up enough to idle on its own. Thats no problem, i expect that since there is no choke. However the engine (and thus the whole car) shakes like crazy while this is happening. There are small backfires ocassionally while this is happening. Under load (while driving) it runs fine. But sitting still in neutral or with the clutch pushed in and reving the engine it shakes like crazy and like i said it has little backfires.
The head was rebuilt in late 2006 and it doesnt have many miles on it since then. Compression is 120 across the board. Carb does have a vacuum leak around the primary throttle shaft but i have attempted to correct that with a steel washer with a rubber backing on it on the throttle shaft against the carb base in an attempt to seal it. I dont know if that would cause the problem i am having or not, I dont think so tho. I have a smaller vac leak on my 76 in the same spot and it doesnt act up like this. Any ideas whats wrong? Could it be tiiming related? It has points and im not sure how accurate ive ever had it.
Usually when my 78 (duraspark, no points) does this, I replace the plugs cap and rotor, then double check the fuel/air mixture and timing. Seems to work fine. I usually end up spending about $30 on all the parts.
The vacuum leak is most possibly the cause, though.
My 78 had the same symptoms and it took me two weeks to figure out that it was the cracked EGR valve. I removed the valve, fabricated a block-off plate, took off the EGR tube and bought a plug for the exhaust manifold connection. Never really had any problems since.
Quote from: dave1987 on January 09, 2010, 01:54:38 AMThe vacuum leak is most possibly the cause, though.
Do check this first. If your car has manual brakes, check the vacuum 'tree' at the rear of the intake manifold. The big capped vac hose connection on mine often springs a leak and does what yours does. The rubber caps deteriorate quickly.
Other vac lines can crack and break at this age.
You should have a choke - what is wrong with it? I think it should be water temp sensing.
I assume spark plugs look okay...
Funny you mention disty caps - mine has the original cap at over 153K miles!
Quote from: dave1987 on January 09, 2010, 01:54:38 AM
Usually when my 78 (duraspark, no points) does this, I replace the plugs cap and rotor, then double check the fuel/air mixture and timing. Seems to work fine. I usually end up spending about $30 on all the parts.
The vacuum leak is most possibly the cause, though.
My 78 had the same symptoms and it took me two weeks to figure out that it was the cracked EGR valve. I removed the valve, fabricated a block-off plate, took off the EGR tube and bought a plug for the exhaust manifold connection. Never really had any problems since.
I have an EGR plate that I built that I need to put on it.
I need to also mention that I cant seem to set the timing right. When I time the engine, i set the dist at the #1 tower on the cap. The engine wont start or starts very hard at that setting. I end up having to push the distributor all the way up against the block to get it to run and run right. Cant set it by the light either. Wont run right when its set to spec.
Also, I have an MSD blaster 2 coil. Will that work with the points? That puppy will throw some voltage to the plugs!
Quote from: 78txpony on January 09, 2010, 08:57:47 AM
Do check this first. If your car has manual brakes, check the vacuum 'tree' at the rear of the intake manifold. The big capped vac hose connection on mine often springs a leak and does what yours does. The rubber caps deteriorate quickly.
Other vac lines can crack and break at this age.
You should have a choke - what is wrong with it? I think it should be water temp sensing.
I assume spark plugs look okay...
Funny you mention disty caps - mine has the original cap at over 153K miles!
Plugs are fine. Choke is not installed. I have the pulloff installed just so it has the seal to seal up the vacuum hole. There is no butteryfly for the choke installed and the linkage isnt hooked up to the choke pull off.
Car does have manual brakes and I have noticed that the vac caps dont last too long. However this problem has occured with this car since ive had it (got it in 2006) and ive had numerous caps on it.
I think it IS time to remove the vacuum fittings in the intake and install pipe plugs tho.
Just for the record, My 79 has the original spark plug wires on it. Dont know about the cap and rotor but they could be original too. Only 100k on it tho.
Sounds like your cam belt may be incorrect. Set your crankshaft to top dead center (0*), pop the rubber frapits off of the belt cover and check to see if the "bump" on the cam is correctly aligned with the center of the three marks on the rear cam cover.
If not, redo the belt as shown (sort of - later model 2.3) here: http://turbotbird.com/techinfo/CamTiming/Cam%20Timing%20Belt%20Replacement%20and%20Set%20Up.htm (http://turbotbird.com/techinfo/CamTiming/Cam%20Timing%20Belt%20Replacement%20and%20Set%20Up.htm)
Mike
I've timed that thing 15 times if i've timed it once. The other two pintos ive got (also 2.3s) dont have these problems and i've put timing belts on them as well so I dont think thats the problem. I think i may be misleading when i say it backfires. It only does it a little bit every few seconds when the engine is not under load and while holding the engine at high rpm (2 or 3k rpm). This is when it shakes and makes backfires. Even then its just every few seconds and sometimes it pops worse than others. It runs too good for the belt to be off much if at all. This is a daily driven car, it idles good and drives fine but I know something isnt right. I've never thought its had the power that it should have, its a 74 2.3 4 SPD 3.55. Theoretically it should be lighter and have more power than my other two pintos (76 2.3 3.00 4 SPD and 79 2.3 3.08 C3) but oddly enough my 79 with the C3 has the most power.
Anyone know about the MSD?
I was going to say the same thing, to recheck the timing belt around the auxiliary shaft sprocket. Since you've done that already....
Have you check the drive-gear on the distributor? I've heard, lately, about that causing problems for some members.
With my 78's 2.3, I have removed the distributor, then dropped it back into the motor at a different angle, one that would allow the same advance/retard adjustments, but with more room to adjust. This is all done without removing the timing belt.
that drive gear has been an issue in the past for me but each time the pin in it broke, it would not run at all. I could reposition the distributor but that would be a bandaide fix. It should run decent with the rotor pointed to #1 tower. I must have something wrong somewhere is all i can think. If the points or dwell was off would it cause this?
I installed the MSD Blaster 2 coil tonite and it dramatically improved the shake but its still there some. The backfiring you cant hear much if at all. New plug wires are going on it tomorrow. Will report back my findings. May be time to try the matchbook trick rather than a feeler gauge.
Consider buying a Motorsports multi-index crank sprocket or (as I did) a Racer Walsh adjustable cam sprocket. You mentioned you had a valve job done, and if it was surfaced (likely) your cam timing is retarded. I wound up advancing my cam 4 1/2* and am considering another 1/2*.
Yes it was shaved .005"
I installed a new set of plug wires last night and it made no difference. The new MSD blaster 2 coil i installed did tho ;) Still not fixed totally but it helped.
Sounds like you've found the main source of your problem!
The head being shaved? Would .005" make that much difference?
Or did you mean the coil?
The distributor could be off by a tooth too,,, stick a wad off butt wipe in the number one cylinder turn it over by hand and when the butt wipe blows out with a pop stop,,, then put a long small clean stick in the # one plug hole turn the engine back and forward a little by hand and find top dead center of the piston,,,then take off the distributor cap and see if the rotor points to number one wire on the cap if it dont then pull the distributor out a little and turn the rotor till it lines up with number one and replace it Hint: put a chalk mark on the base of the distributor lined up with number one on the cap this will make it easy to line the rotor with... P.S If you find top dead center and pull the distributor cap and it`s lined up with number one,,, then thats not the problem>>>> :read: Before you change the wires start it in the dark and watch for sparking lift the wires too and look
"....I think i may be misleading when i say it backfires. It only does it a little bit every few seconds when the engine is not under load and while holding the engine at high rpm (2 or 3k rpm). This is when it shakes and makes backfires. Even then its just every few seconds and sometimes it pops worse than others....."
sounds more like a 'misfire' than a 'backfire'
Quote from: pintoguy76 on January 12, 2010, 01:25:06 AM
The head being shaved? Would .005" make that much difference?
Or did you mean the coil?
Smog cams are already retarded at LEAST 4* from the factory back in the old days.... their high tech solution to more stringent smog laws. That said, if you are already 4* retarded, ANY amount shaved retards it even more.
Quote from: srt on January 12, 2010, 03:30:39 AM
"....I think i may be misleading when i say it backfires. It only does it a little bit every few seconds when the engine is not under load and while holding the engine at high rpm (2 or 3k rpm). This is when it shakes and makes backfires. Even then its just every few seconds and sometimes it pops worse than others....."
sounds more like a 'misfire' than a 'backfire'
The day I started troubleshooting this problem the exhaust had broken off a couple feet behind the engine. The exhaust is fixed now and you cant really hear them anymore, but there were obvious small backfires happening every couple seconds. There wasn't any pattern to it, it wasn't consistently happening every "X" number of seconds, it was just random.
Quote from: slowride on January 12, 2010, 03:29:51 PM
Smog cams are already retarded at LEAST 4* from the factory back in the old days.... their high tech solution to more stringent smog laws. That said, if you are already 4* retarded, ANY amount shaved retards it even more.
The guy at the tire shop I use has an adjustable cam gear he said he'd sell me for $30. I probably should pick that up. He used to race pintos and 2.3s on dirt tracks.
my 78's 2.3 does this too, small backfires/misfires. I always assumed it to be rich mixture and just an issue with my carb. Guess I should play with timing it a bit, again.
Thing is, I have timed it over and over, PERFECTLY timing it with the correct professional tools that my cousin uses to time the motors in the drag cars he builds. Nothing seems to fix it. As far as me and him are aware, the head has never been shaved, even when the motor was rebuilt. Could be they shaved it and didn't add the charge to the receipt though, since he used his company name to have the work done under, in order to give me a discount on the work.
On another note, I have noticed that it smooths out A LOT once the motor is at normal operating temperature. It smooths out a little more once I adjust the distributor timing as well, but then it idles to high and i adjust the curb idle to compensate, then the random misfiring/backfiring comes back.