[NYGTO]

I would like to recurve and rebuild a spare distributor for strip use, but the distributor service needs to know the cylinder pressure. The trouble is I'm 1200 miles away from my car (taking care of my parents) so I can't check. Would anyone have an idea of typical cylinder pressure for a good running stock 1965 GTO with a vintage 068 camshaft? Thanks in "quick advance" (pun intended :---)

[scott06]

Originally Posted by NYGTO

I would like to recurve and rebuild a spare distributor for strip use, but the distributor service needs to know the cylinder pressure. The trouble is I'm 1200 miles away from my car (taking care of my parents) so I can't check. Would anyone have an idea of typical cylinder pressure for a good running stock 1965 GTO with a vintage 068 camshaft? Thanks in "quick advance" (pun intended :---)

Do you mean compression pressure as in doing a compression test?

my stock 1965 is about 175 -185 psi on each cylinder

[Cliff R]

Since I do this for a living I'll say right up front that stock points units are very well set-up right off the bench for the applications they were intended to be used on. Not trying to question anyones skill sets or put a big black cloud over someone who wants to "recuve" one, but it's not going to need much help for what you are doing.

The fact is that I've spent the better part of my adult life REMOVING aftermarket POS spring/weight kits, or the attempts of others to "recurve" these units by putting stock parts back in them and going back to or very close to "stock" settings. A well thought out engine build, especially an early higher compression engine isn't going to need all the timing in right off idle and much of it either.

What the unit needs is to be completely/correctly rebuilt with a new advance pin bushing installed. The factory used a thin rubber sleeve which is seldom still in place or any good if it is. I make a stainless steel one here and use it in the distributors I set-up.

Anyhow, as for the question at hand it should be good enough to supply the CID, static compression ratio and cam card events to your distributor service. If they have extensive experience with these things they will know exactly what to do from there.

The stock curve with stock weights/springs will have the mechanical advance starting right off idle and add timing smooth and steady thru the RPM range till it reaches full advance. It's a good idea to replace the VA unit, even if they still hold vacuum as the rubber in the original unit is half a century old.

That part of the job is getting to be more difficult as a LOT of the better VA units are discontinued and NLA.

[NYGTO]

Yes Scott, that's what I meant. Thank you for the psi information. I was thinking around those numbers too, I'll go with.

Cliff, I had a friend who was a top-notch mechanic/racer and supervisor for a large local police department. His first statement to new hires was "always make sure whatever you are working on is broken before you start repairing".

Thank you for the real-world explanation. I'm trying to squeak out some low-end power because the short time on a stock 1965 GTO is "not that good" at 2.14


I try to leave around 3,000 rpm and keep the rpm above the "all in" advance. By having full advance at 2500 or so I might shrink the weak short time. I hope this makes sense. Lebanon Valley Dragway with pit crew daughter.



Thanks again, Gary