Big Block Distributor difference between a 65 and a 68

[Lawrence S.]

I know there is a groove in the 65 distributor and not in later models, but curious if someone can explain in more details the difference and why you can't run a non 65 distributor in a 65 396.
Thank you

[David H.]

I know there is a groove in the 65 distributor and not in later models, but curious if someone can explain in more details the difference and why you can't run a non 65 distributor in a 65 396.
Thank you

Lawrence

Other way round. Extract from a 2015 John Hinckley post on CF.

Link below. #6 on that thread.

Dave

There's a lot of misinformation out there on this issue, but what it really boils down to is that the distributor housing with the partial oil annulus can reduce or interrupt oil feed to the lifter galleries unless it's installed just right; the distributors with the FULL 360* oil annulus can be installed any way you like without affecting oil flow in any way, and those distributors are spec'd by GM as the replacement for ALL early big-blocks, as well as all other SB and BB applications. The distributor housing oil annulus has nothing to do with the rear cam journal groove and 3-hole grooved bearing issue - they're two completely separate design problems.

https://www.corvetteforum.com/forums...questions.html

[Lawrence S.]

Thanks David. So it’s totally safe to run the later model distributor in a early big block?

[David H.]

Thanks David. So it’s totally safe to run the later model distributor in a early big block?

Lawrence

Yes. As noted, later distributors were spec'd by GM as replacement for ALL early big-blocks ....

John Hinckley, "JohnZ" on Corvette Forum, about a good a source as you can get. I believe this topic was in one of JohnZ's many articles in various Corvette magazines, but easier to find on CF.

Dave

[Lawrence S.]

After I posted my question, I found several posts by JohnZ about this. When I had my 69 Z28 I would frequently ask him questions about the car. He was so helpful to our car community.
Thanks again Dave.
Lawrence

[Hebert K.]

Can someone please explain,
"the distributor housing with the partial oil annulus can reduce or interrupt oil feed to the lifter galleries unless it's installed just right"
I thought Chevy distributors were installed one way, with the vacuum advance canister located on the passenger side of the engine pointing roughly to the front right side of the engine.
Thanks

[Joe L.]

Lawrence

Yes. As noted, later distributors were spec'd by GM as replacement for ALL early big-blocks ....

John Hinckley, "JohnZ" on Corvette Forum, about a good a source as you can get. I believe this topic was in one of JohnZ's many articles in various Corvette magazines, but easier to find on CF.

Dave

Dave------


I completely agree. The "full round" distributor drive gear will SERVICE all 1955-82 Corvette distributors. As a matter of fact, if I had an engine that was originally manufactured with the "half round" gear, I'd replace it with the "full round".

One thing to keep in mind, though: the above-referenced standard distributor gear cannot be used with engines converted to roller cams unless those cams are manufactured of austempered ductile iron or have a cast iron, pressed on gear. Few have either of these.