1975 buick 455 engine

[Bassem ABOU ANTOUN]

Hello guys I have a 1975 buick engine and it has low power (215 hp) and i want to restore and upgrade it.
I was thinking of replacing the heads with 1969 ones (more compression) and replacing the intake manifold with edelbrock performer intake and replace the qjet carburator with edelbrock 750 cfm carb. Do these edelbrock parts work well with the 1969 heads and the engine? What you think about this combo?
My goal is to reach 370-400 hp with this engine. So what should I upgrade with the engine to reach my goal?
Please any suggestions in hp increasing will be welcomed.
Thank you

[bob k. mando]

are you aware that the earlier heads are designed to oil the rockers by weeping through the shaft?


they can still be used on the later block, but you'll need to be very careful about sealing the oil and water passages because there are various small changes in the shape of the holes in the block.

http://www.buickperformanceclub.com/idblock.htm


certainly, the 1975 heads are junk. large combustion area, zero quench, don't flow all that well.

see how expensive it's going to be to get a set of 69 heads in Lebanon ... then check the TAPerformance.com web site. their aluminum heads will flow better than a max porting effort set of OEM cast irons out of the box. they're much pricier than a raw set of irons but if you were going to pay for porting anyway, you'll likely make that back.

another issue with the early heads is that they use different diameter pushrods ....



and replace the qjet carburator with edelbrock 750 cfm carb.


you're going backwards. the 75 Quadrajet was factory rated at 800cfm ( actually flowed ~780 ). worse, Buicks like big carbs.

i wouldn't put a massive carb on the Buick unless you're going to do a bunch of racing as an oversized carb is going to kill your low end driveability. but if you're going to insist on getting an Edelbrock, 800 is the bare minimum.

alternatively, you can get a quality Q-jet rebuild.

first thing to take care of for any serious power build is to make certain that your distributor / advance curve and carb are in peak working order.


My goal is to reach 370-400 hp with this engine.


should be pretty easy. you don't mention a cam, you'll definitely want to swap something else non smog in there. a lot of people like the RV grind for around town cruising. torque for days.

TA will be able to advise on this.

look up the oil passage upgrades and try to have a Buick or Land Rover ( the 3.5L-4.6L Rover engines are actually the Buick small block from 1961-63, just everything is in metric ) guy do the rebuild. Buicks like tighter bearing tolerances of around 2 thousandths of an inch. you get some Chevy guy doing a 5 thousandths rebuild and that engine will grenade inside of 5000 miles and you'll never be able to get it to keep pressure up.