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sps314 · 08-13-2002, 04:27 PM

I have a 79 Trans Am with a 403. I put a 400 out of a 76 Grand Prix in it but it sits too high in the front the fan shroud wont fit, the alt bracket is too high, etc. Are the engine brackets different on Firebirds than other pontiacs, I used the brackets from the Grand Prix. Any help would be appreciated,

Thanks

sps314 · 08-13-2002, 04:27 PM

I have a 79 Trans Am with a 403. I put a 400 out of a 76 Grand Prix in it but it sits too high in the front the fan shroud wont fit, the alt bracket is too high, etc. Are the engine brackets different on Firebirds than other pontiacs, I used the brackets from the Grand Prix. Any help would be appreciated,

Thanks

Brian Baker · 08-13-2002, 05:16 PM

Something is amiss. When installing a 455 in my 79 T/A, I used brackets and pulleys from a 400 that came out of a '72 Catalina. The fan shroud was the same as what was in it with the 403 (as was the fan and clutch assembly). Everything fit fine. Engine mounts in correct? The chassis side of the mount stays in the same place for the Olds or the Pontiac engine (only thing that changes is the engine side of the mount).

Brian Baker · 08-13-2002, 05:18 PM

Also, brackets between the 403 and 400 cannot interchange.

sps314 · 08-13-2002, 05:56 PM

I used the engine mounts-brakets from the Grand Prix and the fan, alt etc. for the 400. I left the frame mounts in same place. It sits too high in the whole compartment but is really bad in the front. Pontiac told me the moter mounts are the same for 403 or 400 just the brackets on the engine were different. I don't know what the problem is. I will answer angthing else if anybody has any ideas.

Thanks

Brian Baker · 08-13-2002, 06:23 PM

Transmission mount? I'm stumped.

STripleduce · 08-13-2002, 06:47 PM

I have the correct mounts but havn't gotten them out yet.
http://performanceyears.com/ubb/ulti...c;f=5;t=000375

[ August 13, 2002, 06:51 PM: Message edited by: STripleduce ]

Brian Baker · 08-13-2002, 09:24 PM

I missed the part about the GP mounts. That's the problem. You need the F-body mounts for the engine. Thanks for pointing that out ST'Duce.

sps314 · 08-14-2002, 12:19 AM

Ok lets see if i got this now, I need the engine brackets for a Firebird with a 400 Pontiac engine, right? How about the mounts on the frame, they are the same as the 403, right? Now which holes on the cross member do they bolt in, the upper or lower, the left side is different? The tranny is a TH350 and it is the one that came with the TA, I didn't change the mount. Another thing, will the oil and temp sending unit on the 400 work or do i have to change them? I am starting to feel hopeful about this project.

THANKS for the expert help

STripleduce · 08-14-2002, 05:59 AM

You need the clam shell type.To find the right spot to bolt them ,I cant tell you which holes to use( as most frames I've seen from that year were drilled to take any bolt pattern fron 351 buick-350 small block cheb-455 PONT)but I do know that the space between Cent-Cent on the mount bolts is 16" for PONT.

Lemans1 · 08-14-2002, 11:47 AM

I put a 400 in a car that had the 403 and the frame mounts were fine right where they are, they just used an adapter on the 403 block. As for the engine mounts, I have used them from Grandvilles and such and went right into firebirds with no problems. I thought they were pretty much all the same. Maybe its just the later G-bodies??

myckee · 08-14-2002, 03:28 PM

If you are using the mounts, that attach to the crossmember, and are the same ones that the 403 used, then you already have the correct mounts. As far as the engine brackets go, the brackets used in the G-body cars are DIFFERENT than those used in the F-body cars. Your engine is sitting funny because the wrong brackets are being used.

The proper pieces are:
LH: 496893
RH: 496892

I just called my local dealer and these parts are discontinued, however you should be able to find some around. The brackets on Firebirds with 301 engines are the same.

sps314 · 08-14-2002, 04:23 PM

I need the metal brackets that bolt to the engine for a Firebird and leave the cross member mounts alone as they are the correct ones and in the right place. Sounds like this is going to work after all. Are there any electrical changes I need to know about?

THANKS

myckee · 08-14-2002, 08:03 PM

I can't think of any electrical changes, but your fuel line is on the wrong side. Nothing a little rubber hose won't fix. As well, the upper and lower rad hoses are different. Ohter than that, it will be an easy swap.

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