[davidm]

Hi, I have a 1973 Pontiac Firebird with a 350 engine, I want to put something bigger in, what is the best option, current motor pushing 300HP need about 400 plus. I am looking at fitting a disc brake kit to the rear end.
also any advice on drivetrain mods would be appreciated. Looking at buying a crate engine, thanks in advance.

[WDCreech]

David, all Pontiac engines have the same external dimensions, so a 455 will fit right where that 350 is. You didn't say what transmission that you have, so I can't offer any advice there.

[davidm]

Thanks Bill for your reply,
as far as I can ascertain, the transmission is the original 3 speed unit.
In terms of the 455 engine, is it much heavier than the 350 unit?
and any idea who builds the best crate engines.

[grivera]

Welcome to the best Pontiac forum on the net! My brother has a '73 bird project that he may do an LS swap into. I love the 2nd gens.

There are many good builders out there. As far as crate engines, these deals from Len Williams Machine shop are hard to beat:

http://www.lenwilliamsautomachine.com/Home.html

[davidm]

many thanks

[indymanjoe]

Butlers have some nice crate Pontiacs.http://www.butlerperformance.com/index.html

[b-man]

Originally Posted by davidm

Thanks Bill for your reply,
as far as I can ascertain, the transmission is the original 3 speed unit.
In terms of the 455 engine, is it much heavier than the 350 unit?
and any idea who builds the best crate engines.

There's only a scant few pounds difference between the weight of the 350 and 455. Due to the longer stroke crankshaft in the 455 it weighs a few pounds more, but it's really an insignificant weight difference.

[davidm]

Thanks guys, I am talking to Len Williams regarding a 455 motor, he is fitting an edelbrock 2156 performer inlet manifold and recommends an 800CFM Holley Carburetor, any recommendations on a good supplier for one of these?
thanks in advance

[WDCreech]

David, a stock cast iron intake manifold will out perform a Holley Performer any day!

[davidm]

Ok noted, so what do you reckon is the best Carb option?

[WDCreech]

I like the Quadrajet for street/strip use because of fuel mileage on the street. For race only, I run Holleys.

[77 TRASHCAN]

Originally Posted by WDCreech

I like the Quadrajet for street/strip use because of fuel mileage on the street. For race only, I run Holleys.

david,
www.cliffshighperformance.com

[davidm]

Having trouble sourcing a pair of replacement radiator grilles for my 1973 firebird. I have heard that the grilles from a 1972 model will fit.
Not to concerned about the different appearance as the firebird is modified any way.
can some one please let me know if this has been tried before?
thanks in advance

[Squidward]

Originally Posted by davidm

Ok noted, so what do you reckon is the best Carb option?

I replaced my Qjet with a Quick Fuel carb. Loved it right out of the box.

http://www.quickfueltechnology.com/c...arburetor.html

I like the aluminum aftermarket intakes. The performance difference appears to be negligible, and I like the weight savings. Besides, you have carb options instead of being limited to the spreadbore pattern on the factory intake. Different strokes. (Cue Gary Coleman with "What you talkin' 'bout, Willis?")

Since you aren't worried about original engine, how much do you care about original engine appearance?

[carbking]

Originally Posted by davidm

Ok noted, so what do you reckon is the best Carb option?

David - there is no "best carb option". If there were, all would be running it, and you would not get the different opinions.

You posted this in the "street" forums, rather than the race forums. So I will assume most of your use will be on the street. For street-driven vehicles, ALL of the manufacturers went to spread-bore setups for MOST (not all) engines.

Carter (TQ), Holley, and Rochester (Q-Jet) all have produced spread-bore carburetors.

For a crate performance engine, UNLESS YOU HAVE ONE OF THE CARBURETOR SPECIALIST BUILD ONE SPECIFICALLY FOR YOUR ENGINE, all carburetors are going to need some tuning (some more than others). Thus, pick the brand with which you (if you do your own tuning) or your tuner (if you hire it done) is most familiar with, or wishes to become familiar with.

Generally speaking, power and driveability are going to depend on the skill of the tuner moreso than the brand. As to fuel economy, some brands tend to do better than others. But since you are going to install a 455 instead of a 400 or 350, I will assume fuel economy is not number 1 on your list of priorities.

Personally, I have Carters on ALL my performance vehicles, but am probably in a minority on this board.

Jon.

[455rebel]

The q-jet is a much better street carb than anything I have used.
Now at the track I like Holley .

[carbking]

To add some information to post #15:

In the list of manufacturers producing spread-bore carburetors, I forgot to mention Motorcraft. However, about the only calls we get for them are for numbers matching Fords, and most of the Ford guys that drive their cars have removed the Motorcraft, so easy to forget.

Jon.

[Tim Corcoran]

I agree with Bill the stock cast iron manifold is a great performer and in will out perform many of the after market manifolds including the performer. Unless your going racing the factory manifold and a properly rebuilt Quadrajet are hard to beat.

[Will]

Ditto comments on factory manifold with a properly prepped Q-jet. Q-jets require internal modifications to work well on big cube "built" engines though so you need to source on from someone who specializes in them (see the link to Cliff above, but there are others.)

'72 grilles will NOT fit the '73 nose. The '73 is a one-year-only design and the grilles are shallower than the '70 - '72 and won't interchange.

[leeklm]

"Thus, pick the brand with which you (if you do your own tuning) or your tuner (if you hire it done) is most familiar with, or wishes to become familiar with."

Well said. After reading Cliff's carb book and experimenting with a few Qjet's, I am very pleased with the driveability and performance from my custom qjet. Meanwhile, I have only spent a short amount of time fooling around with a generic Holley 750, and cannot get it to run worth a crap compared to the Qjet. But, I am sure plenty of guys on this board could!

Do a search here on the forum for intake manifolds, and give yourself plenty of time to soak it all in. Lots of good info.