My 16 year old son can buy an 84 4 cyl Firebird cheap and we have an 88 4.3 engine available. He wants more than a 4 cyl and we don't want him to have a V-8 yet. Is this a possible swap? Is it an easy swap? He also has access to a cheap 85 Trans Am with a frozen 305. Aside from purists and resale issues, would the 4.3 be easier to put in this car? Thanks!

 

The 4.3 engine is basiclly a 350 engine with
the back two cylinders shaved off. The 700R4
That bolts up to the V8 also bolts up to the
4.3 V-6. So in my Opinion the work load would
be the same as putting in a 305 or 350. Look
through the archives for more info. My advice,
If you really want to swap in a new engine there are plenty of watered down 350's or 305's out there, that produce around or under
170hp. I've just swapped in a 350 on my 91
RS which was a V6. Now I'm finishing up the
wiring and exhaust system. This project was
alot harder and more expensive than I had expected but it is nearly complete. Do your research before you decide, There is plently of information on the board to help you.

 

Good luck passing the smog check. Unless your planing on putting in the fuel injection that came with the 4.3 you'll never get it registered in Ca.

The best thing you can do is to get the 85 and find a decent smallblock and swap it in exact. If it's already got one in there as you said then it's a simple bolt in process and it's legal. I doubt it would cost more than $1000 if you shop smart when you look for the new longblock. The 4.3 swap if you have to buy the computer and wiring will be more and twice the hassle, you'll need to move the mounts and a few other small items.

The trans isn't an issue, the bolt pattern is the same on the 2.5 4cyl, 4.3 V-6 and the SBC/BBC. I know it's funny that you can bolt the same trans to a 2.5 that you can bolt to a 502.

 

The trans on the Four cylinder has the same
bolt pattern. Cool! I did not know this (That's what I love about this board I'm board
I'm always learning something new)!
Is the trans on the Four cylinders internally
weaker Gears, pump, etc? Not that I would
ever use one, but just curious.

 

I don't know if the trans is or isn't any weaker. I've seen V-8 S-10 swaps that kept the 4 banger trans and never had a problem. Of course those were auto's. I'm not a internal trans man, I don't know the insides of one and I don't care too either. I wouldn't think that they are any weaker, The cases are supposed to be the same. I know if I were GM I would just make one model for both and not have to worry. I do know I wouldn't trust a manual trans from a 4 cyl behind a strong smallblock much less a BBC.