Alright,

We checked the compression and are getting about 145-150 PSI on all cylinders except number one, which is about 125.

Is this the cause of all of our problems? The hubby wants to change the ignition to an electronic one....we are out of ideas and the hesitation when we accelerate is so annoying....

 

Now that you've got the readings, it's time to evaluate them to determine just what the future of your engine is going to be.

If the gauge pumps up slowly, such as 30, 50, 70, 90, etc. to an almost normal reading, you probably have ring problems. A general rule is that a maximum reading should occur after two strokes. If oil is added to a low reading and the pressure improves, this will confirm worn rings. A persistent low reading generally indicates valve problems.

Oil lost through worn valve guides will not be determined through compression testing. Low readings can also be caused by a warped head and occasionally, two cylinders will have very low compression which can be the result of a blown head gasket. It is important to remember that the addition of oil to the combustion chamber will not improve the compression readings if your engine has burned, warped or stuck valves. High compression readings can be the result of carbon buildup or head surfacing.

Generally, if the variation between the cylinders is 10 to 15 lbs., this is acceptable, but always check the specs in the manual. It would seem that equal pressure is necessary to have smooth running engine, but it's been found that with only 70% of normal pressure is enough for running smoothly. Also, manufacturers specs usually list a bottom line acceptable pressure and a good engine will usually read 20 to 30 psi over the acceptable readings. Your #1 cylinder reads below the 15 lb. difference from the other cylinders, but it is probably not your problem.

Since you found that your engine has good compression, it may be time to go back over your tune-up steps.

 

Thanks Soaring! I have not had to go through that troubleshooting yet, but that is a great wirte up!

 

OK, hubby said it was 4 revs before the compression reached its peak.

If I am reading you right, this means the rings are bad...

It doesn't smoke, but Dad said that Fords usually don't unless it is really bad....what do ya think?

 

You have compression rings, and you have oil rings. Obviously, your compression and your oil rings seem to be OK because of the compression readings, and you are not burning any oil. Go back and re-check your tuning procedures. Bogging (hesitation)usually is related to the carburetor. I think I understand that it is not misfiring or backfiring anymore, just bogging at high load. Is that right?

 

If the popping we hear is due to the age of the motor, you are correct, we are simply getting the hesitation.


Could the vaccuum lines cause the hesitation?

 

Well, it is a given that all vacuum lines be hooked up with workable if not new vacuum lines. Now, we are getting down to the nitty gritty. What carb do you have, and are you sure it is dialwed in correctly for your application?

 

Let me get back to you with the number on the carb, I know it is a Holley and we were given a book on it but it is a universal guide and the receipt isn't in it.

 

Thats good compression. My 66 shop manual says a allowance of 20 psi is allowed between cylinders. It's odd, because my number 1 cylinder compression is lower then the rest too, but my engine smokes bad when you rev it up.

 

It sounds like you need to do some engine work charles. I would love to know the history of my engine. it couldnt be running strong, and never have been rebuilt.