[Lynn]

I am running the exact same short block as you, although mine started life as alate 69 L46. Same crank, rods and pistons. It is also in a 69 Z.

Had the same decision to make 4 years ago. You mention "day two driver". Two things you should strongly consider IMHO: detonation and flat tappet cam wear.

I never saw where you addressed fuel. Being in Houston, I know you have better pump gas avaialable than we do in OKC. Not sure why, but best pump gas here is 91. Seems every time I drive to TX, there is plenty of 92 and 93 avaialable. Right now fuel isn't an issue for me, as I am 1.5 miles from a Municipal airport that sells 100LL to the public at 3.99 per gal. Don't know if you have that luxury.


Get the quench between .035 and 040. No more. No less. Tight quench helps ward off detonation.

Really hard to to beat the LT-1 cam which is what I went with. One of my main considerations was that the LT-1 could be run reliably with the stock valve springs. That minimizes the chance of wiping a cam. Good lubrication is essential, but I am not opening up that can of worms in this thread, as there are PLENTY of those threads.

Back to detonation, if you are stuck with pump gas, I will tell you that I could not run my LT-1 combo with as much timing as I wanted with 91 octane gas. Had to back it off about 4 degrees. Now, with a mix, I can run full advance. If I were stuck with pump gas, I would consider opening up the heads just a bit to lower compression, or if I had the engine apart, an even better solution would be to cut some off the tops of those pistions (that big single dome kills flame travel anyway).

If you are keeping the big domes, and small combustion chambers, bleeding off some static pressure with a bigger cam will probably help, but as mentioned by others, you may be on the edge when it comes to creating enough vac for power brakes. And... now we are back to cam wear, as you are going to need stiffer springs for the bigger cam.