Thanks Soaring... That's what I should have done in the first place instead of trying to take a shortcut. [sm=bangbang.gif]

 

OK, I've retested going straight by the book... took out all plugs, pulled the air cleaner and made sure the flaps were wide open. As someone mentioned, my readings were all higher, ranging from 190 to 175 (The 175 being the one that read 145 yesterday). So, I believe I can be pretty certain that it's not a compression problems... which rules out rings or valves.

Now, I had another idea... my valve covers are leaking pretty good. Is it possible for the oil from the valve cover leak to seep around the threads on the spark plugs and that's the oil it's burning?
Course, if that was it, I would think it'd smoke constantly instead of just when I'm putting my foot into it.

...or could it be the oil rings as someone mentioned earlier? If it's just the oil rings that wore/broke, and not the compression rings, would I still have good compression but still be burning oil and fouling plugs?

Any thoughts? ...thanks again.

 

hettar-
just curious, but have you checked your distributor cap???


I, too, recently did a compression check on my 66 that i just purchased. i admit that i didn't pull all the plugs either. i got a consistent 125 all the way around on the 289. does this sound tired out to you 289 builders? to answer my own question i suppose i should run the test correctly.

 

That's a possibility. Get your car in a dark place, then open the hood and start it. Do you see any fireworks under the hood? Those two cylinders just may not be getting enough fire. I know it is a long shot, but a cheap test.

 

I dunno shikoz, from what I saw on my tests, I could pretty much just add 30 pounds to each of the readings I got from the test with the spark plugs in and would get the same results from what I tested with the plugs out. I believe I can say now that if you're just looking for bad cylinder(s) - lower than 75% of your highest reading - you can determine that from either test. But as a disclaimer, since this is the first time I've done this, it's possible it could've just been a fluke and there may be other situations where the results could differ.

Oh, and, yep, I did change the distributor cap and rotor button when I changed the plugs two weeks ago. However, I didn't change the wires. I believe I'll give that dark room test a whirl... or just go ahead and change em since I don't really know how old the ones on it are.

Dang, this is a cool forum. [sm=Awwww.gif] I've learned more in the past two weeks since joining up than what I thought I knew when I got started!! ...if that made sense.

 

In a normal street application using stock rings ( not file to fit ) you should see about a 10% maximum variance from the average. In other words, if your average cylinder pressure is 150 then the lowest acceptable would be 135 and the highest would be 165. I agree with Soaring on this one, it's a leak. I suspect that the valve seals are bad and the guides are worn on those valves in those cylinders. JMHO, Dean

 

Thanks guys... truth be told, I'm kinda itching to try my hand at a rebuild. I just wanted to prove I had a good excuse to do it.. so if I screw it up too bad, I can say, well, I had to try!!

 

Bottom end sounds solid to me, I would suggest only doing the top, maybe just add a set of aluminum heads and a mild cam. Why rebuild something that is still good? Of course if you wanted to race it, then its an entirely different situation.

The reason I say aftermarket heads is simple. By the time you replace guices, valves, possibly some seats (or all the seats for unleaded gas) do the valve job and a new set of springs, locks, retainers, you could have bought a set of ready to run E heads for just a little more. Why not get a better head for the money if it isnt a 100 point restoration, and more like a daily driver?

You could use some 40 year old valves if you really want to, and the rest of the moving parts too. Just giving you options and ideas, not tellin you what to do.

 

Yeah, for about a thousand bucks U.S. , you could have some dang nice aluminum heads that would set you back in your seat if you have the intake, carb, exhaust and headers to support the air flow.