[Alfgard]

Hello,

first of all, I'm sorry for mistake I can do, I'm french and try to speak english.

I have a 1979 firebird with a 1973 350 pontiac motor.
I have an edelbrock performer intake manifold with a 750cfm edelbrock carb.


A stock 350 is about 170 hp, i'm right?

my question is the exhaust is with a cat, and stock exhaust. I want to remove the cat, do you thing I can reach 250hp without it? like the 1971 350? or not?
I think change the entire exhaust systme would be better but in France it is expensive and don't have the money for now!

thank you


(edit correct mistake)

 

[NOT A TA]

Couple things involved in your questions. The way horsepower ratings were done changed in the early 70's. Previously the engines were tested without accessories like fan, alternator, etc. and so the numbers look better than after the change.

The carb is probably a bit big for your 350. A 575-650 would probably work better overall.

Unless the converter is plugged you probably wouldn't notice much if any performance gain by replacing it with a straight section of pipe.

Without more info on how the 350 is built HP would be a guess.

 

[Alfgard]

thank you for your answer.

i've no idea how the motor is build,
I buy this car few month ago, and she was imported from Indiana

I found only it is a low compression with 6X cylinder head, If i'm right the gain is 3cc and better intake valve?
what do you thing about the ignition advance? 12°@ 650tr/min is it good ?

 

[ponyakr]

"...I found only it is a low compression with 6X cylinder head..."

6X heads were used on late '75 thru '79 400 & late '75 thru '77 350 engines. The 350's came with 6x-4 heads, which had the smaller chambers which were said to be aprox 93-94cc. Some 400's came with 6x-8 heads, which had larger chambers of aprox 101cc. As far as I know, all 6X heads came with 2.11 intake valves & 1.66 exhaust valves.