I just bought my 1st ever pontiac and have a lot to learn, I hope you guys can help. I picked up an 89' Formula 350 and am going to put a mildly built older chevy 400 into it. I am not sure how old the motor is but at one time it was in a 68' Impala. Will it bolt in or will I have to make some modifications? I was also wondering if the heads will have to be changed. Will I have any issues with keeping the TPI? Thanks.

 

The 400 SBC and the 350 are the same external dimensions. Everything fits. As far as the TPI, it's got the wrong intake bolt pattern for the 400, plus it will probably run out of breath really early.

 

Can I change the heads and pick up aftermarket intake so it will be less restrictive? I haven't bought the 400 yet but I like the price.

 

Yes, there are several aftermarket options for heads and intakes.... you do realize that you will need ECM tuning, etc to get it to run right when you are making a change like this, right? It isn't as simple as bolting on another intake and everything will be fine. It's better to start with your goals and budget and go from there then a "how can I do this" when it may not match either your goals or your budget.

 

Thanks for the info, I may look at rebuilding the motor that was in it.

 

The 400 didn't come out until 1970, so if it was in a '68, it was swapped in.

Vortec heads with a Vortec-type Holley/Weiand Stealth Ram would be a good choice.

The 400 is externally balanced and is 2-piece rear main seal. You'll need to find an external balance 153-tooth flexplate if you want to use your original starter (make sure the block has the same starter mount bolt holes as your current engine before you install the 400 in the car).

Headers highly recommended if you don't have them already.

 

Thanks all for the info, I don't want the headache. I have decided to rebuild the 5.7 that is in it through a local machine shop.