[C2] Recommendation for Engine Work
Thread Starter
Instructor
Joined: Feb 2016
Posts: 138
Likes: 9
From: Edwards CO
I think Jim has a point - #8 is dead. The plug electrode shows no sign of firing from what I can see in the picture. First, determine if you have a bad plug or plug wire or distributor cap, rotor, etc. Check the porcelain to see if you have a crack. I have had many bad new plugs over the last 50+ years
Also, if you can, do a quick leakdown test, but if you can't, listen in the carburetor as you or someone cranks if over with the coil wire pulled, might not be able to tell if the valve seat good or not unless it is real bad. Listen for unusual lifter / rocker arm noise indicating excessive clearance or weak or broken valve spring. You don't have to pull the valve cover, just stick a hose in your ear and run it along the top of the valve cover. If you have no popping in the exhaust or carburetor, your probably have no mechanical issues.
I am hoping you have a bad sparkplug. If you move a known good one to #8 and clean up the one from #8 and put it in another cylinder the good plug was removed from and run the engine you can see if you get the same buildup and or performance (you have to have a miss with that plug) in a few miles.
You can use your timing light to monitor the plug / wire while the engine is running by putting it on the #8 wire and watching it flash at idle. Some plugs will fire until the compression increases with rpm, so that doesn't always give you a good indication, but may.
Also, if you can, do a quick leakdown test, but if you can't, listen in the carburetor as you or someone cranks if over with the coil wire pulled, might not be able to tell if the valve seat good or not unless it is real bad. Listen for unusual lifter / rocker arm noise indicating excessive clearance or weak or broken valve spring. You don't have to pull the valve cover, just stick a hose in your ear and run it along the top of the valve cover. If you have no popping in the exhaust or carburetor, your probably have no mechanical issues.
I am hoping you have a bad sparkplug. If you move a known good one to #8 and clean up the one from #8 and put it in another cylinder the good plug was removed from and run the engine you can see if you get the same buildup and or performance (you have to have a miss with that plug) in a few miles.
You can use your timing light to monitor the plug / wire while the engine is running by putting it on the #8 wire and watching it flash at idle. Some plugs will fire until the compression increases with rpm, so that doesn't always give you a good indication, but may.
Thread Starter
Instructor
Joined: Feb 2016
Posts: 138
Likes: 9
From: Edwards CO
Drifting
Joined: Jan 2007
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From: Melbourne FL
St. Jude Donor '09 & '11
I think Jim has a point - #8 is dead. The plug electrode shows no sign of firing from what I can see in the picture. First, determine if you have a bad plug or plug wire or distributor cap, rotor, etc. Check the porcelain to see if you have a crack. I have had many bad new plugs over the last 50+ years
doesn't always give you a good indication, but may....
doesn't always give you a good indication, but may....
Thread Starter
Instructor
Joined: Feb 2016
Posts: 138
Likes: 9
From: Edwards CO
My way of thinking about is that even if cylinder #8 was totally dead, such that you were running on 7 cylinders and if the mixture in those 7 was spot on, you'd be getting more than 6 - 8 MPG. So, regardless of whatever is going on with cyl #8, I don't think your carburetor is jetted correctly.
And one more point, the idle mixture screw(s) affect the idle mixture. Once you are running at hiway speeds, the jetting determines the air/fuel ratio. The mixture screws are out of the picture.
And one more point, the idle mixture screw(s) affect the idle mixture. Once you are running at hiway speeds, the jetting determines the air/fuel ratio. The mixture screws are out of the picture.
Le Mans Master
Joined: Sep 2009
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From: "You may all go to Hell- and I will go to Texas- Davy Crockett
St. Jude Donor '12
Just for grins, pull the carb and look down inside the intake manifold to see if there is a film of oil inside the plenum. The pvc may be malfunctioning, and the #8 cylinder is typically the one that fouls out with oil....
Thread Starter
Instructor
Joined: Feb 2016
Posts: 138
Likes: 9
From: Edwards CO
Jets are stock for the 3810, and I've set timing, dwell and all other tuneup parameters per the shop manual.
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From: Really Central IL Illinois
Seems like if it is jets or power valve, all 8 plugs would be running rich not just #8. How are the others? I understand being one handed, you are lucky to be where you are with the troubleshooting.
Guess I'm lucky, back when I was making a living on the road, my wife got an engine in a 64 El Camino ready to pull before I got home. She also helped put the new one in. She balks at just about anything in the garage now. I can't understand, she is still young, I've only worked her for 53 years.
Hope you find someone to help.
Guess I'm lucky, back when I was making a living on the road, my wife got an engine in a 64 El Camino ready to pull before I got home. She also helped put the new one in. She balks at just about anything in the garage now. I can't understand, she is still young, I've only worked her for 53 years.
Hope you find someone to help.
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From: Colorado Springs Colorado
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I’m in Colorado Springs at 6200' elevation and probably 1000’ lower than the OP. I have a size 64 Jet as the primary and a 72 for the secondary and also changed my squirter size to a 37.
Race Director
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So, newps, exactly what jets are in the carburetor on your car? Are they the same as the altitude-adjusted jets in warrenmj's carburetor?
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