what is good compression for a stock 69 440?or the percentage difference to be good ?thanks.

 

yea i was checking the cylinders with a compression gauge and need to know what good and bad.so far got 105 on #6 115 on#4 125 on #2 and 130 0n #8 did easy side first.thanks with a sun tech gauge

 

had wife turn engine over till gauge quit rising then when she stopped the gauge started going down.is it bad gauge or bad engine.or bad checker.i had all spark plugs out is that what your supposed to do .

 

thaks deadkelly ill put some fresh plugs in and recheck.what is the champion plug parts number i want.thanks

 

I would warm the engine up first. Then test cylinders each twice to get an average. It does not really matter if you take all the plugs out at once or one at a time. I do one at a time.

With your compression going all over the place it's not a good sign. But, give us more history?

1.) What vintage is the engine?

2.) Has it ever been rebuilt before?

3.) Has it been driven exclusively in town?

Part of what could be happening is just carbon build up which can be removed.

Dating myself but in the old days we would throw in a quart of ATF, top off the tank with high test gasoline and take it down the highway at a 100 miles per hour for at least 5 - 7 miles and then back to 60 -70 miles per hour for one hour.

Return to shop and retest all cylinders. This being said there are modern day combustion chamber cleaners that you run through the carb but I would suggest dropping the oil afterwards and replacing the oil filter.

MM

 

ill check again later let you all know.ripped a finger nail plum off taking spark plugs out.the finger was one i had all ready chopped end off when i was a kid lucky i even had a nail any ways pretty sore today might be a few weeks before i can wrench again.thanks

 

motor is a 69 model.dont know history probly rode hard and put away wet.does have a cam with a lop.and has been running richh.trying to solve this problem 2 different carbs same prob.thinking dist.have had car for 10 years but only been drivable last 2 years and drove very little.had the car checked out supposably ,starting to doubt the person.they said cam was to big and had blow by.im checking compression then going to pull valve covers off and see how oily,had off few years ago and was super clean [like its been rebuilt]so im going to check again and see .and go from there.

 

Sometimes when you think it's running rich it is really just a needle valve under the fload that is either dirty or has an obstruction.

Take off the top and check it out. Another common issue is the case top of the carb may have loose screws which allows air to be drawn it causing a similar problem.

Maybe tighten them up first and see what happens.

MM

 

thanks ill try that but did it with 2 new a different carbs.carter afb 625 and holley dual line 750 carb new

 

havent got to it yet kinda waiting for some warmer weather ,ill let you know.thanks