Thread: big block chevy HP question

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Hello guys im new to the board and probably will have a lot of questions now and in the future I hope you can help me out with. First of all this is my first big block build and im just curious of HP numbers.. If I knew then what I know and hear now I would probably have done things different. I got a good deal on a 427 short block(crank pistons and rods) so I jumped on it. then as I began to build this street/strip engine, as I did my research I found out that I had a "Tall Deck 427.. and the bottom end consist of .20 over flat top pistons with one valve release standard truck rods and steel crank. As I continued on the the process I got a deal on some closed chamber heads that came of a 69 Chevelle with 396 engine in it casting (8917215) and had them ported polished and cnc I had a 3 angle valve job and installed 219 valves in them, I also installed comp cam heavy duty springs and 1.7 roller rockers, also changed camshaft to a(K11-214-4) hydraulic flat tappet comp cam 575/575 changed the intake to the "TD" Edelbrock Supervictor as well... holley 850 dp Msd pro billet distributor and 6AL msd box... that pretty much sums it up as to what I have but I've heard so much about these engines just would like some input on hp numbers ball park figures to decide whether im gonna get rid of it of put some juice on it and ride out!! thanks guys

with the 396 215 heads i stop putting big valves in them casting less you open up the chamber. you will see not much gain. the 427 and low cr flat tops you will be lucky if you have a CR over 8.5 so 450hp if your lucky with headers .i take 427 tall decks and make 510 /540 out of them other then that there just not a good deal for most as they can be more work and money intake or spacers .better push rods .damper . and then getting them to fit with out custom headers is very slim chance

Pat, would fenderwell headers work better than conventional headers?

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Originally Posted by techinspector1

Pat, would fenderwell headers work better than conventional headers?

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in what ? nova and all A body cars any thing past 2 inch tube your going one or two tubes around the frame less custom i done 2 1/4 and 2 3/8 all in the frame on 1969 newer nova s and mid year vetts.. A body Gm 1966 and up . older chevy II s 63/66 towers need to be cut back and with a 9.800 deck block two tubes inside the rails and two up and over .

thanks pat McCarthy how much nitrous do you think I cn spray on it?

Originally Posted by ratmotorrookie

thanks pat McCarthy how much nitrous do you think I cn spray on it?

you have the 4 ring stock cast 427 pistons in this ? you running a fepro steel fire ring gaskets like a 1017 or 1037. what is the ring gap all play in to much you can spray . with them heavy cast pistons in that engine and 4 5/64 rings will kill you for any hp i would never build it the way you have it or even spray it... But i would think if the bottom end has clearance right tune 125hp i would lose the pistons use a small dome 2618 aluminum piston use a longer rod if your low buck if not then build it to a 525 or 540 last one i built made over 650 hp at the wheels