How hard is it to put a 400small block engine in my 91Z28 Auto. Is the 400 small block basically the same as the 350 small block?
Also it's not a stroked 350? What do i need to slip er in? I'm lookin for big power.

 

400s and 350s are virtually identical on the outside. What do you need to make big power ? Very deep pockets!

 

from my understanding it should be a easy swap motor is pretty much the same outside and the tranny should bolt up

 

[QUOTE]Originally posted by TBI305Camaro
[The tranny will bolt right up!!!

 

Can i get a crank with a 1 piece rear seal to fit or will the original 2 piece seal crank fit with no problem?

 

You need a 400 flex plate to go with the 400. That takes care of the 1-piece/2-piece issue. You will have to use the 400 balancer which will cause the timing mark not to line up.

Otherwise, it will just bolt right in. You need better heads and induction than what you have; the TPI chokes a 305, let alone a 400. Whatever your peak power point is right now, your peak power RPM with a 400 will be 350/400 times that. i.e. if your car makes its peak HP at 4400 RPM now (typical for a TPI 350) its peak HP will be at about 3850 RPM with a 400.

 

How come the timing marks won't line up witht the 400 balancer? Is there a way to adjust the timing tab?

 

2 reasons:

THe 400 balancer is 1" larger diameter than what your timing tab is designed for; and your timing tab is in the later model location near the 12:00 point. The earlier model location, at about 1:30, is unusable because the power steering pump is in the way.

 

No 400s ever came with rollercams, so plan on a retrofit kit or a flat tappet cam install, with new lifters. The two piece rear main seal shouldnt cause any bolt up problems, but it is not as effective as the one piece. There are ways of curing this easily; so look em up. Plan on boring out the core you find to 406, because the poor rod to stroke ration chews up the right and left sides of the bore. Along those lines some hypereutic pistons and a balancing go along way with thes engine. You will also have to machine your head for the steam holes in the 400 block; use a gasket as a template. Take add cc s from the combustion chambers and porting will help make the most of the cubes.

If you have any q's ask, I can look them up if I dint know off the top of my head.