how to make a 4 bolt main pull over 300 hp

[no_doz]

anyone got any ideas on what would make a 350 4 bolt main pull 300 horses? im not sure how easy this is to do (id figure easy because im pretty sure most of those pull around 250, but i dunno). im gettin ready to put this motor in my 92 firebird & im thinking a 4 bbl intake manifold & a 750-1000cfm holley dominator carb/headers & free flowing exhaust?


thanx, js

[Rob B (shoebox)]

A decent cam, heads and headers should make it relatively easy.

[fastTa]

A nice single plane intake like a Victor Jr, a decent size 4 barrel carb and headers should put you pretty close to 300. It will greatly depend on the carb, cam, and heads.

[Joe 1320]

heads with 2.02 intake, 1.70 exhaust with a 3 angle valve job, at least a 268 advertised duration cam at the minimum, headers, exhaust, single plane or midrise dual plane, decent carb and you are right there.

[fastTa]

You don't even need larger valves or ported heads to make 300 HP out of a 350 inch SBC. The rag mags are constantly testing different 350 SBC combos. Super Chevy just got 422 HP out of a stock bottom end 350 with stock cast iron Vortec heads(1.94"/1.50" valves), 1.6 roller rockers, and Edelbrock Performer RPM Air gap Vortec intake manifold, Holley Street Avenger 670 CFM carb, and a CC 218/224, .462".469", 110 LSA.

The rag mags are constantly getting well over 400 HP with stock Vortec heads, a fairly small cam, and a moderate carburetor. Just bolting on a set of Vortec heads alone will get you pretty darn close to 300 HP.

[Joe 1320]

You don't even need larger valves or ported heads to make 300 HP out of a 350 inch SBC. .

True, it' just a little easier.

[fastTa]

True, it' just a little easier.

Yep, and sounds better too.

[Joe 1320]

just to back up what Kevin said, I was able to get 350HP still using stock valves, an original Torquer single plane intake, moderate cam, headers, Holley Carb, and a few other misc bolt ons. Also, a 4 bolt main is simply 4 bolts per bearing cap vs. 2 bolts..... for added stability and strength.

[no_doz]

vortec sounds great, but its expensive & i want to remain using carbureted methods.

[fastTa]

vortec sounds great, but its expensive & i want to remain using carbureted methods.

You can find a pair of fully assembled Vortec heads for less than $400. Do a search on cz28.com and ls1tech.com. Even brand new Vortec heads through Summit are only $519 for a pair. And $739 for the Vortec heads that are assembled to accomodate up to .550" of lift.

Vortec heads work just fine with carb setups.

[no_doz]

but everytime i look for em they are made for FI setups? also where can i pick a set up for under 600? i looked on jegs & they were like 1200

[94Z/28]

but everytime i look for em they are made for FI setups? also where can i pick a set up for under 600? i looked on jegs & they were like 1200

The cylinder heads dont care if the motor has a carb or is fuel injected, you just have to have a intake manifold that is for a carb and has the vortec bolt patern. Edelbrock has a couple that are for vortec heads I think they are makeing the RPM Air Gap for vortec heads now. Also you need to check Jegs again they are listed in the newest catalog for $249 each, also summit has them for about the same price.