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I am putting together a 2 bolt main 427 bbc with casting 3916321 (1969 Corvette)
Edelbrock alluminum heads 60439 (complete with valves) - Valve seat job done to ensure full seal.
H stamped GM rockers
Isky 264 264 .630 108 cam with compatible Isky flat tappet solid lifters
10:1 speed pro pistons
AED 1000 HOBK carb
Weiand stealth intake
MSD AL6 + billet distributor R5671A-7 NGK 4091 Racing Spark Plugs
Tufftride steel crank
Weiand high volume water pump
Hooker supercompetition sidemounts without silencers
What's your guess on HP figures and engine rpm range if adequately tuned?
From: At my Bar drinking and wrenching in Lafayette Colorado
The cam you're describing is the Isky "Z89." You do know that cam requires compression ratio at 11:1, 4.56 rear end ratio, 7500 rpm, and has a "rough" idle - it is intended for drag racing. It is a rougher cam that the '69 ZL1 solid cam, and the 108 LSA will make it a lot rougher than the L88 or the ZL1 (neither of which were on a 108 LSA). If you're actually building a 7500 rpm 427, it should put out power in the 650 hp range.
Your 2-bolt block is generally considered a sub-6,000 rpm block. To get it to operate reliably over 7,000 rpm, you'll want to use studs, and you might consider fabricating and installing main cap support straps. I installed 1" thick 4130 steel cap support straps with studs on the 3 center bearings on my high-rpm 2-bolt 407 small block just to make sure it stayed together - my weak points are front and rear caps, which have not yet caused a problem....
Thanks for the input. This engine is supposed to be ran max to 6.6 to 6.7k rpm at most.
It is intended for a road race application on long races (2 to 3 hours).
The car must be geared to allow mostly climbing up swiftly from about 3k rpm to about 5.5 / 6.0 k rpm. Occasionally up to 6.5 or around there as previously stated.
I have a "proper" 4 bolt 12.5:1 compression engine but I want to avoid long races with it.
Can you advise where can I get the straps you refer to?
Many thanks
From: At my Bar drinking and wrenching in Lafayette Colorado
I machined them myself, along with the machine work required to the main bearing caps. Howards Cams makes a strap for the forward cap on a small block, but I'm not aware of anyone making straps for the 2, 3, 4 caps - all the ones I've seen have been custom made by the engine builder. This video shows how to mod the engine for the straps on a little 4-cylinder engine - in addition to machining my own straps, I used the method shown in this video to prep the main caps for the strap installation. The mod makes the bottom end very strong, and makes the 2-bolt block viable for serious rpm usage:
MKIV 427 build - HP guess
