whats up all, I'm planning a 400 swap into the GTA, I'll be retaining everything off of the 5.7 as possible, what years should I look for and what problems will I run into. Thanks!

 

Any year, except for the first couple of years when they had 3 freeze plugs down the side and all came with 4-bolt main caps installed. They're all the same other than those. Those have less metal around the main webbing.

You'll have to use a 400 balancer, which won't have the right timing mark for your timing tab; you'll need to have a flex plate or flywheel for a 2-piece RMS motor, and get it "unbalanced" to the stock 400 balance spec; you may need to have one extra starter bolt hole drilled, if you plan to use the small (12¾") flex plate; you'll need to drill 6 little holes in each head; and if you want it to actually run better than what you've got, you'll need some other induction system besides a stock TPI to keep it from cratering at about 4200 RPM just like it does now at 4600 RPM, because it doesn't flow enough to support a 350 much less a 400. If you put a TPI on a 400 you end up with the same HP (flow) you had before, it just occurs at a lower RPM because of the more inches. Of course, you don't want to use the stock 400 heads since they are 70s smog garbage that caused those motors to only put out 180 HP in stock form, but you have to be careful with your head/piston combo to keep the compression ratio withint the tolerable range.

 

thanks for the reply, will the stock heads work? I'm just looking for a cheap alternative to add power and potential during my engine teardown and I'm a bit uneasy about having a stroker. How will the 400 affect the accessories and mounts? I read I would need a new tq converter too, thats understandable. Couldnt I just use a stock 400 flexplate and a 400 replacement starter? I do plan to use my stock induction (for now) clean and port the heads and probably a new cam. Also buying a 400 from a junk yard and rebuild it.

I am really unfamiliar with camshafts... I understand, correct me if I'm wrong... that L98 has a hydro cam. In order to use the stock heads would I need a hydro cam? Would a 400 throw off my O2 sensor? Could I still use the stock distributor? Would the stock heads bolt up? I have edelbrock headers, do think I'd be able to retain them? Also which oil pan would I use? Thanks so much.