3.4 in a firebird

[montess408]

hey guys i am going to start a build for a friend of mine soon and i need a little info the car is a 89 firebird with a 2.8 tbi and he needs a rebuild so i said to put a 3.4 out of a newer camaro the 3.4 bottom end will be rebuilt to stock hes not looking for mad power he needs it to run good
are the 2.8 heads the same as 3.4 heads in valve size and chamber ?
and i was going to use the 2.8 intake manifold and maybe a 4.3. tb with a little p&p work with headers that should work fine right ? let me know guys


thanks

[Joseph Upson]

hey guys i am going to start a build for a friend of mine soon and i need a little info the car is a 89 firebird with a 2.8 tbi and he needs a rebuild so i said to put a 3.4 out of a newer camaro the 3.4 bottom end will be rebuilt to stock hes not looking for mad power he needs it to run good
are the 2.8 heads the same as 3.4 heads in valve size and chamber ?
and i was going to use the 2.8 intake manifold and maybe a 4.3. tb with a little p&p work with headers that should work fine right ? let me know guys


thanks

It's all the same stuff except for the stroke and cylinder bore so no problems switching attachments around. 1984 was the last year to my knowledge TBI was installed on the 2.8L IN THE firebird so unless the car has been modified in someway you should put the MPFI intake system that should be on the 2.8L on the 3.4L.

If however the 2.8L in the car is an OE TBI engine from an S10 then you'll actually be stepping up in head performance because the HO heads were reserved for the Port fuel injected engines, starting in 1985 Fiero, camaro and firebird, the early HO chevy citation and later the TBI 3.4L.

[geoffinbc]

No not true ALL iron heads were exactly the same after 86. By then everything had EFI and all used the "HO" heads with the larger valves.

The 2.8L manifold nor the 3.4L manifold would fit a 4.3L TB. It is a very large throttle body I don't think you would be able to bore out the manifold to fit. You should use all the 3.4L Camaro intake parts if possible. They are all superior to the 2.8L Stuff

[montess408]

i read in a older post here that you could do the 4.3 t.b. swap if you swaped the body of the 4.3 with the 2.8 injector or somthing like that anyways not sure how good that info was but i am just doing a simple swap so that why i wanna keep the intake and t.b of the 2.8 dont wanna have to change the harness and ecu for the newer injection witch would probly be better but i am not looking to make alot of power just somthing wit h alittle more grunt than the little 2.8 that all

[Ray Hamilton]

I used the Holley 400 cfm TBI and bored out a 2.8 manifold to 4.3 gasket size w/o any problems.

[86euro]

Doesn't matter anyway, an '89 Friedbird isn't tbi. It's mpfi.

[geoffinbc]

Exactly. That whole 2.8L to 4.3L TB is for TBI only.