onenice3.4

i have a 1976 Firebird 400 motor and i was wondering if it would fit in an 86' trans am

Captainofiron

iTrader: (1)

Geez, I dont know, but my gut instinct is no. You do realize how much wider the Poncho 400 is than a Chevy SBC. Plus it outweighs it big time. Plus the motor mounts are different. Now you could do alot of stuff to make it fit, I have seen a couple 3rd Gens with Chevy 454s, but they are race cars with no inner fenders big chunks of the firewall cut out, stuff like that.

So IMO it will not fit, unless you cut alot of material.

onenice3.4

thats all i needed to know thanks man

Captainofiron

iTrader: (1)

No problemo

Here is a comparison so you can see how much wider the pontiac is

30thanniv

iTrader: (2)

It has been done and requires relatively minor mods. The engine is not that much wider then a sbc. People think big cubic inches means big physical size. That is not true. It is all in the bore and stroke. As far as weight, there may be a difference, but nothing that big that can not be worked out. The problem you will have is headers. No out of the box fit. The advantage in this case is the downward facing exhaust ports. Ofcourse for headflow the straight out shot is better. This causes straight out shot a la chevy to create the packaging problems as mentioned above. Additionally a big block chevy head is like twice as wide as a 400 head.
Call Jim Butler he can set you up .

FYI a poncho 400 or 455 is not a big block as many would have you believe. They are identical in outer size. So for the most hp for the money run the 455.
Good luck

Captainofiron

iTrader: (1)

I never said the 400 was a big block, in fact I usually try to educate people about how the whole big block small block nomenclature doesnt apply to all makes of engines

Anyways, I was just trying to help him out, and it is alot wider, I have a Chevy 350 sitting right next to a Pontiac 400 YC block in my garage.

I had to buy a different engine stand for the Pontiac, because when I was mounting it I let the engine hoist down slowly and the whole engine stand started bending downward with the weight of the engine hahahaha it was crazy to see.

30thanniv

iTrader: (2)

I never accused you of calling it a big block. I know you that you are aware of the difference.
As far as width and weight, there is no point debating, but the differences are not that great. If need be I can supply the dimensions and dry block weights for both. In any case the engine will fit. The headers will be something to contend with.

y2k_ta

iTrader: (80)

The engine swap would also require a lot of rewiring and plumbing. The gas tanks in third-gens have a return feed line that you'd have to deal with or remove altogether.

I don't know your location, but there's always local emissions laws to worry about (since they're different depending on your location).