From: mshar@mentor.cc.purdue.edu (Mike Mshar)
Subject: Re: '87 Trans Am Modifications
Organization: Purdue University Computing Center
Date: Mon, 9 Nov 1992 05:27:12 GMT

In article <1992Nov7.031544.6822@ra.oc.com> rodder@ccwf.cc.utexas.edu (Jon D. Rodder) writes:
>In article <BxBG46.HEL@mentor.cc.purdue.edu> mshar@mentor.cc.purdue.edu (Mike Mshar) writes:
>>> Stephen James Kendrish <sk4k+@andrew.cmu.edu> writes:
>>>In need of advice.
>>>
>>>     I'm telling myself that I'm investing money into my '87 Trans Am to
>>>get more money out of it than I'll put into it by reselling (a lot of
>>>people probably say this).  I probably will not sell it, however, when
>>>I'm finished with it.  I bought the car for $3000 R-Titled.  The body
>>>work is still excellent and the 305cid non-TPI motor runs great for
>>>116,000 miles.  I feel like I got a pretty good deal.  
>>>     
>>>     Anyway, at this moment I'm having a 400SB Chevy being built for it.
>>> I got it for $200 out of a 1970 station wagon (70,000 mi.).  First of
>>>all, I'm wondering if the transmission and rear end can handle this
>>>power?  It has the TH700R4 Automatic OD transmission and stock rear end.
>>
>>Will the body be able to handle it?? I have seen and heard way too many
>>bent up TA stories to ever consider putting a quality engine into one of
>>these cars. Did you ever notice that you never see 5.7 TPI IROCS with
>>t-tops (with the exception of one year, 1987 I believe)? Know why? The body
>>could not handle the torque. Plus, a 1970 400 engine is going to be a lot
>>heavier than a 1987 305. The newer engine has aluminum brackets, intake
>>manifold, etc. while everything on the 400 will be cast iron. So, the front
>>suspension will definitely need to be beefed up.
>
>The 87 engine also had a LOT more smog equipment, etc.  I doubt that the
                          ^^^^^^^^^^^^^^^^^^^^^^^^
>400 will weigh significantly more than the 305.  The 400 accessory brackets
>most likely weigh less than the beffy 305 aluminum brackets, btw.  And
      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>if he's going to all the trouble of doing this swap, why not spend
>an extra $100 on a new aluminum edelbrock manifold? 

No, not really. The only piece of smog equipment with any appreciable
weight to it is the AIR injection pump. The EGR valve doesn`t weigh but a
pound, the computer weighs little more than that, and I assume that the
converter will either be left on the car or replaced by a heavier dual
exhaust setup. Sure, it looks like spaghetti in there, but really most of
it is just vacuum hoses and electrical lines. Oh, there is also the vapor
canister (another pound), and if you count the stock air cleaner, maybe
another. But that is all there really is. So emmsisions control devices
really do not put that much weight onto a car. As for the weight factor, my
brother put an early model Olds 350 into his Cutlass (iron intake and all),
and it simply weighed more than the 305 it replaced. In fact, the springs
eventually had to be replaced. Maybe the Chevy 400 is different?

BTW why would a car company use aluminum brackets if they weighed more than
the cheaper steel ones they replaced??


>>A 700R4 will not last behind a 400. Period. The only way it will is if it
>>is ripped open and modified by a good tranny guy. As for the rearend, if it
>>is a 10 bolt posi, it will probably be OK. 
>
>I disagree...  I have a friend running an 87 700R4 behind a 90 HO350
>with no problems in 30,000 miles.  I'm running a 91 4L60 (the new designation
>for the 700R4) behind a 450hp blown 350.  SO far, no tranny problems,
>but I don't have many miles on it.

I am truly surprised. The reason for this is probably because the 700R4 was
modified a bit by GM in 1987 (Hot Rod Magazine), and could handle more
torque. Time will tell, I guess. All I can say is that I love my TH350.
Has your tranny been modified at all??

>As far as the rear end goes, the stock 87 rearend will NOT take a moderately
>built 400.  My friend with the HO350 went thru two of them in the first year
>he had the 350, and finally went to 12 bolt.

Again, a surprise by me. My Nova had a 10-bolt behind a BUILT 350, and it
held up pretty good. Maybe they were weaker in later years?


Again, I think that the most important question is whether or not the body
could handle the torque of a built 400. I had an `82 TA, my friend has an
`84, and still another friend has an `86?, and none of these cars had the
body strength to handle a real engine. People I know tried it and regretted
it, so that`s my testimonial. 
-- 
|       Michael G. Mshar        | My Life-Long Goal: To keep common sense    |
|   mmshar@mn.ecn.purdue.edu    | alive and keep the idiots from taking over.|
|  mshar@mentor.cc.purdue.edu   |     \\President, Nice Guys Anonymous//     |
|____>>> United States Steel, Mechanical Engineer, Technical Services <<<____|
Newsgroups: alt.autos.rod-n-custom