a suggested 10:1-10.3:1 engine compression combo, long tube headers, low restriction exhaust , roller rockers and larger injectors ETC. it easily supports a couple hundred more hp than stock, ID suggest you use 32lb injectors and a 3200 rpm stall converter and a crower 00471 hydraulic roller cam
file:///C:/Users/prlan/Downloads/camtag00471.pdf
and 1.6:1 roller rocker on a 383-400 sbc
I assume you have a stealth ram base, and ideally you'll port the lower to maximize the intakes potential, obviously check all clearances carefully

http://garage.grumpysperformance.com...41/#post-92695

http://garage.grumpysperformance.com...90/#post-91807

BTW if you want to go into making some more Ill sell you the MILL I used to make these I paid $almost $12K with the tooling and ID let the mill and tooling go for $5K http://www.grumpysperformance.com/sfmill1.png

theres a whole lot more involved than simply posting a few dimensions,
I happen to have two, modified plenums, now obviously I'm keeping the one on my corvette,
but I can save you a good deal of time and cash if you want to buy the spare plenum for $300, and give me your shipping address.

http://garage.grumpysperformance.com...383-combo.430/

if you had a local machine shop duplicate one, it would easily cost you $500 in materials, welding and machine work, etc.
for a custom Holley stealth ram c4 plenum
I have the one on my TUNNED PORT 383 corvette and a spare, from the last production run,
I ran the spare plenum for a short time on a test engine, but its just fine functionally, and would work perfectly on a properly ported stealth ram lower, on a 383-400 sb engine with the correct stealth ram base, matching mods like cam,

let me look that info up,and ill get back to you shortly

Hello,

First I would like to say thank you for contributing so much knowledge to the community, it is very much appreciated. Next, I was curious as to if you have the specs/measurements for the custom Steathram plenum to fit the C4. All of the old links to purchase are dead, and I haven't been able to source exact details. I was planning on fabricating a new plenum, and since you had spent so much time and effort figuring out what works..... it made sense to ask.

Thanks,

Mike C