84Z51J

Thanks for the input Confab. What do your static/dynamic compression #'s look like? Still on the stock pistons/cam/fuel/spark?


Gibbles didn't end up using Vortecs, but there was a ton of great head & cam info in those threads/subthreads--many thanks to you, Indycar, and Grumpy! Highly recommended reading for any budding mod enthusiast.


Based on continued research , it is looking like OEM Vortecs are not going to be the best option for my project. After some educated adjustments to my math...maintaining .040 quench (.025 deck + .015 steel shim gasket), changing to 64cc heads, & keeping the stock cam & pistons will push 9.15 SCR / 5.57 DCR up to 10.44 / 6.29. Runnable? Probably. Room for more cam? Probably. Advisable as a package? Probably not.


At $150/pr for known good Vortec cores, and $300 for a V8 valve job & resurface, I'll be in for well over $500 once the intake pattern is tapped, guides cut, & hardware added. Decent cost in itself for fresh heads...but, I can get a brand new China Special set at a similar price point, with peace of mind included (once I clean up the castings & install a name-brand valvetrain). The machine shop also re-emphasized that, based on their own experience, OEM Vortec castings are too thin to reliably tap for a conventional SBC intake.


I know it's been done, and I may still do some comparison shopping. I just can't confirm exactly how crack-prone the heads really are--opinions vary wildly. For half the cost, I'd take the risk...but wrecking them would take the budget right out of my budget build. In the interest of reliability and wallet-friendliness, I'm going to err on the side of caution. Will be keeping an eye out for some secondhand/reman aftermarket heads, preferably with the heart-shaped chamber a la Dart Iron Eagle. One version has a 72cc chamber, which would start me at a much more manageable 9.54 SCR / 5.79 DCR. The other is 67cc, which (for static) is about as high as I'd be comfortable with at 10.08 / 6.09.


Having taken some time to turn the pros and cons over in my head, I'm not happy with the cam compromises that would have to be made to keep the stock brain--especially when I already intend to upgrade it soonish. I must have contracted a touch of Whileimatit-itis, but I feel better So the cam will wait for now, which gives me time to save up for EBL & cut my tuning teeth. Perhaps more importantly, it allows for expanded grind choices & thus a better end match to engine/ECU capabilities.


Comp never did get back to me, but my application is odd and the details are still changing...I'll resubmit my info to them & others once head choice is locked in.


Gibbles--just a heads up, my numbers conflict slightly with yours. I believe the stock '82/'84 forged TRW pistons have a 3.4cc trough valve relief, rather than the 5cc from your compression calcs. Reference here: https://www.corvetteforum.com/forums...p-pistons.html

Gibbles

Nice find, makes me even more glad I went with the 70cc heads.

And it really comes down to what fuel, I have race fuel available to me a few blocks away, however I want the ability to wander and not be tied down to an octane...

One of my favorite things to do with the car is to just get in and drive and see where it takes me.

safer side of caution is better than pushing that envelope if your not wanting to modify the computer or change the fuel injection system out.

Of all the information I found while planning the build, I received the best from grumpy. And not just information on what to use, but to actually understand why ect.
It's a fantastic resource IMO.

84Z51J

Hit the nail on the head there. Love having an 87 octane sportscar!

I want to! The issues are: 1) resource limitations, and 2) my own trepidation about adding too many variables as a first-time tuner. I think I could do it...but knowing before I pull the trigger (as much as I can reasonably absorb, anyway) saves a small fortune in time, money, & frustration

For sure. Bookmarked

corvettenorway

this is the best treat for renegarde / crossfire i have ever read