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I have a 1973 Chevy 350 v8 (in a 1980 k10) that is missing on cylinder 2 and 8( front and rear most cylinder on the passenger side.) It has headers and an Edelbrock 600 cfm carb and intake manifold.
About a month ago I felt a miss that would come and go. It, eventually, became constant and (recently) became worse. Because of the intermittent nature I assumed it may be related to the carb. I had a shop, that I have dealt with for many years, rebuild it. The problem still exists.
Over the last year I have replaced:
-coil
-plugs
-wires
-Dis cap n rotor
-valve guide seals
-push rodsI’m thinking it may be the “HEI” distributor going. Cause I have checked compression, spark, and rocker arm movement. The distributor has a little bit of rust inside and a minute amount of “side to side” play. nothing looks broken.
Any additional trouble shooting ideas would be nice.Thanks
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Replies
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Interesting problem you have here. Sounds like you’ve covered a lot of the bases. That said, I’m still thinking mechanical issue. You may have good compression but if you have a worn lifter it might leak down too fast and not move the mix through the cylinder efficiently. If it were a carburetor problem I would think it would effect everything on all the runners in the ports that side of the intake the carburetor feeds. Meaning, I would think you would also have a miss on 2 other cylinders on the opposite side of the engine if the carburetor was at fault. You replaced the ignition parts that could cause an issue (cap and rotor) and you have good spark. Although you might try swapping the ignition wires around to make sure they’re good as well. If you can’t find vacuum leaks for the effected cylinders that leaves something mechanical. The play in the distributor sounds normal to me. Also, if it was a distributor problem I would think it would effect more than just 2 cylinders specifically.
A leak down test would not be a bad idea but what I really think would help here is a running compression test which can only be done with a transducer and some equipment to interpret the readings.
Keep us posted on what you find.
Thanks Eric. I am unfamiliar with the “running compression test” you mentioned. Money is an issue for me right now, so I won’t be able to get it towed anywhere. When I did the compression test, all the cylinders built pressure very quickly and held it very well on the dry test. All the rockers appear to be moving the same amount. I understand that a tiny variance in lift can translate to a large amount of valve movement. This situation is really aggravating because I have seen these motors put up with alot of abuse and just keep running fine. Do you think it would be advantageous to swap around some rockers and see if I get different results?
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