I have a '62 Chevy C10 with a 235 in it. I just can't seem to get it to run right. It runs rough during acceleration. Once I'm up to speed, it runs pretty good. It lacks power and I'm getting about 8 MPG. At idle, there is sometimes a popping in the exhaust, like a burnt valve, and the tach needle bounces by about 200-300 RPM at idle (no pattern to it).
Here's what I've tried/checked: • Timing (I can't find the mark on the flywheel, so I use a vacuum gauge) • Spark plugs • new plug wires • new points and condenser and cap • new distributor • New valves and seats • re-set valves • re-set timing • re-gapped plugs • re-set points • looked for bent pushrod • re-set valves • took the intake and exhaust manifold off and put new gaskets in • switched Rochester carb for Carter carb • Compression test 130-135 in all cylinders Still running the same. Anyone got any ideas???
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I have a '62 Chevy C10 with a 235 in it. I just can't seem to get it to run right. It runs rough during acceleration. Once I'm up to speed, it runs pretty good. It lacks power and I'm getting about 8 MPG. At idle, there is sometimes a popping in the exhaust, like a burnt valve, and the tach needle bounces by about 200-300 RPM at idle (no pattern to it).
Here's what I've tried/checked: • Timing (I can't find the mark on the flywheel, so I use a vacuum gauge) • Spark plugs • new plug wires • new points and condenser and cap • new distributor • New valves and seats • re-set valves • re-set timing • re-gapped plugs • re-set points • looked for bent pushrod • re-set valves • took the intake and exhaust manifold off and put new gaskets in • switched Rochester carb for Carter carb • Compression test 130-135 in all cylinders Still running the same. Anyone got any ideas???
"When we tug a single thing in nature, we find it attached to the rest of the world" ~ John Muir "When we tug a single thing on an old truck, we find it falls off" ~ me Some TF series details & TF heater pics
I have a '62 Chevy C10 with a 235 in it. I just can't seem to get it to run right. It runs rough during acceleration. Once I'm up to speed, it runs pretty good. It lacks power and I'm getting about 8 MPG. At idle, there is sometimes a popping in the exhaust, like a burnt valve, and the tach needle bounces by about 200-300 RPM at idle (no pattern to it).
Here's what I've tried/checked: • Timing • Cleaned spark plugs and set gap • new plug wires • new points and condenser and cap • new distributor • New valves and seats • re-set valves • re-set timing • re-gapped plugs • re-set points • looked for bent pushrod • re-set valves • took the intake and exhaust manifold off and put new gaskets in • switched Rochester carb for Carter carb • Compression test 130-135 in all cylinders Something I noticed today is that the exhaust gasket is blown on the second port between head and manifold (can’t tell if its cylinder 2 or 3, because it’s the same port). I can feel occasional puffs through the leak, but it’s not regular. It seems that when the puffs come through is when the engine misses a bit and the exhaust pops.
Hy Glen_P, please put a vacuum gauge on the engine and tell us how the needle performs during different r.p.m.s, a vacuum gauge can tell you a lot about the condition of any engine, if you know how to interpret the readings, hope that helps.
When the engine is idling, Vacuum reading is at about 19 " hg. It sporadically (no rhythm to it) drops to about 18-18.5. That's that's when the RPM drips slightly for a second (it seems to miss). When I rev it, it drops to about 9 and then up to about 22 when the throttle is closed, and then back to 19.
Hy Glen_P, that is a nice video, could you tell us if you hold the throttle partially open for a while, will the vacuum reading come back up from 9" or does it stay around there. It looks like you might have at least a partially plugged exhaust system, hope that helps.
Hy Glen_P, if your vacuum gauge does come back up to 19" then your exhaust system should be okay. If the vacuum gauge goes down as you rev the engine and never recovers, or continues to go down as you increase the r.p.m. your exhaust system is restrictive or plugged, hope that helps.
Thanks 3B. Looks like I'm back to the drawing board then. If cam lobes are worn, should I get the compressions and vacuum readings above? (vacuum at around 19 and compression at 130-135).
Hy Glen_P, your engine seems to be in good general condition by its compressin and vacuum readings. There are a few things that can cause the sporadick dip on the vacuum gauge, worn valve guides are one thing. I would go back through everything and make sure everything is set where it should be, points, timing, carb settings, just verify everything. Distributors can be worn, causing wierd simptoms as well, just check and adjust things to where they were designed to be, hope that helps.
You'd think it would run better and get better than 8 MPG! I put new valves and guides in 6 months ago and new distributor and seem to be re-checking everything every couple weeks with no change.
What continues to puzzle me is that there is a small exhaust manifold leak on the 2nd outlet (cyl 2 and 3). When the engine misses or drops RPM, I get a "puffing" through this leak. When it runs smoothly, it doesn't puff through the leak. Does that make any sense??
What don't you pull off the intake and exhaust manifolds and replace the gasket. While you are at it, be a good time to replace the carb to intake gasket also. At least that will eliminate the possibility of a leak there.
Where is Saskatchewan are you located? I've been to Moose Jaw, Swift Current and Saskatoon.
Hy Glen_P, did you have the work on the head done because the engine was running poorly? Has the engine ever run well since you've had it? What I'm wondering is if the valves might be a little tight in the head, and behaving sluggishly at times. You seem to have a miss at idle, and I'm wondering if it might be a sticking valve. Were your valve springs tested, and were they shimmed to the proper installed height after the valve job?
I did the head because it was running poorly and it didn't change anything. When I pulled it off, I could see that some of the valves were starting to sink into the seats. So it certainly was in need. I don't honestly know if they tested or shimmed the springs.
Part of why it occurred to me that maybe my cam may not be aligned properly is because I can't seem to locate the timing mark with the timing light. (So I've been timing it by vacuum).
I was paying attention to it today. At idle, the tach needle bounces about 300 RPM, but with no pattern to it. As I accelerate, the engine chugs (almost like it would if it was only firing on 5 calenders). I was cruising home at about 3300 RPM and the engine was running smooth and the tach needle was solid (no bouncing at all).
I'm embarrassed to admit this, but given all the help and suggestions I received from folks on this site, I thought I'd come clean .
I tried timing it again with the timing light and found the light was only firing intermittently. I changed the lead and it didn't change. I put a new spark plug in and she running golden!
Yes - I did replace the plugs in my original troubleshooting, so perhaps go a bum plug. Because I can't see the timing marks (which I finally found), I don't usually use the timing light to time it. Glad I chose to do it this time.
I normally wouldn't admit such a stupid feat, but I though those who have helped me may enjoy the end of this saga!
Hy Glen_P, I'm glad you found the problem, and you let all of us know what you found. So from now on all who read this will have one more thing to check, so we all benefit! Now go out and enjoy your beautiful truck.
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