compression test??

[fitzwell]

riddle me this..

Did a compression check on the 69 for the upcoming F.I. swap. Came up with 135-145 , and one hole at 90. Oiled the cylinder, retest. Same results. Now, here's the thing. I did an RPM drop test, all clyinders were the same, 40-40 RPM drop when i grounded each plug terminal. Put a vacuum gauge to it, got 19 in at idle. Steady as a rock. If i have a weak hole, shouldn't there be a slight flutter in the gauge, or less of a drop on the offending cylinder

The compression test was done cold, going to try it hot tonight. Don't know what (if anything) that will tell me,but the little guy that lives on my right shoulder says i need to do this.


Ideas, comments, magic potions anyone????

[mkpj1]

i think you answered your own question. I always do it operating temp with choke fully open and all plugs out. Still the same,.. maybe you got some funked up spark plug threads or the gauge in threading in poorly?

[Happy_Camper]

Or a leaking exhaust valve.

If you do have an exhaust valve leak, this would be an excellent reason to upgrade to a nice set of aluminum heads and intake, along with headers, a stroker kit, cam, carburetor, ... I'm sure there are lots of knoweldgeable guys here who can help you spend your money

BTW: I've got one of those cylinders too. Since it's the exhaust valve, I'm just driving it.
The cost to replace the valve seats, and complete a valve job, just doesn't make sense for the slight loss in fuel mileage and power. If the valve job gets done, it wont take long to suck the oil right past the old rings, and start oil fouling spark plugs.
It could be as simple as coking around the valve stems, but opening up an old engine like this, is akin to opening a can of worms. To me, it seems like an all or nothing proposition. It starts innocently enough with a leaking valve, moves on to drilling out broken exhaust manifold bolts. Then might as well throw new seals and gaskets at it.
Well, now I've got the thing apart and on the stand. Next thing I know, I'm ordering up all the goodies to build a full on tree trunk pulling, trailer hauling, deisel eating, angry big block. When it would have run just fine for another 10 years...
This is why I'm not even fixing the valve cover gaskets. I can't trust myself.

[fitzwell]

Or a leaking exhaust valve.

If you do have an exhaust valve leak, this would be an excellent reason to upgrade to a nice set of aluminum heads and intake, along with headers, a stroker kit, cam, carburetor, ... I'm sure there are lots of knoweldgeable guys here who can help you spend your money

BTW: I've got one of those cylinders too. Since it's the exhaust valve, I'm just driving it.
The cost to replace the valve seats, and complete a valve job, just doesn't make sense for the slight loss in fuel mileage and power. If the valve job gets done, it wont take long to suck the oil right past the old rings, and start oil fouling spark plugs.
It could be as simple as coking around the valve stems, but opening up an old engine like this, is akin to opening a can of worms. To me, it seems like an all or nothing proposition. It starts innocently enough with a leaking valve, moves on to drilling out broken exhaust manifold bolts. Then might as well throw new seals and gaskets at it.
Well, now I've got the thing apart and on the stand. Next thing I know, I'm ordering up all the goodies to build a full on tree trunk pulling, trailer hauling, deisel eating, angry big block. When it would have run just fine for another 10 years...
This is why I'm not even fixing the valve cover gaskets. I can't trust myself.

o no you don't....

As stated, this is for an upcoming E.F.I. swap. Which is going to open a big enough can of worms as it is. I have a set of stock E7's in the corner that i know are good, so it's not like this is a major ordeal. My Windsor jr.s stay on the shelf for another project.

Happy, the syndrome you are referring to is one a friend of mine named "creeping excellance"
Thankfully, i don't suffer from it...... i enjoy every minute

[Happy_Camper]

for some reason (most likely stupidity on my part), I thought you had a 390.
Yeah, the 302 is not near as big an issue. Everything is small and light, with plenty of room. Definitely want it running right before you start the EFI swap though.
Have fun!