I have a 2 bolt lt1 block and want to make it a 4 bolt. I was talking to my engine builder and of course 4 bolt splayed is best, but since i am on a limited budjet, he recomended finding some used 4 bolt caps from a lt1/4 4 bolt engine. he said they prolly wont have to be line bored (just honed) and will prolly be best for me.
Only thing we didn't know were if the LT1 4 bolts were stepped or flat like older SBC.

Besides drilling/ honing, will the just fit in?? or any expensive decking have to be put on??

THANKS!

 

LT1s are stepped. The chances of not having to bore might be 50/50 if you get some 4bolt straight caps off of a vette block, but IMO youre better off getting new splayed caps, not for strength so much, but they are billet steel instead of nodular iron like the factory ones are, and they will be right for sure. You can have Eagle splayed 4bolts for $80 for all three, youll pay good for the linebore/hone though.

 

The production 4-bolt straight caps are "grey iron", which is not as strong as the nodular iron caps. The caas are stepped as Jon noted and it's relatively simple to machine the extra holes and fit them to a 2-bolt block. You don't say what you are building, but the production iron caps are pretty strong. If your budget is really tight your idea isn't bad, depending on what you are building.

Rich Krause

 

Thanks guys

rskrause, I have made a couple post in the FI forum. I am doing a 355 heads cam ATI P1-sc twin intercooler car.
eagle 4340 3.48 crank, and 5.700 h-beam rods
SRP -24cc dished forged pistons
fully ported LT1 2.02/1.57 heads (flor very well) and i still im up in the air about what cam.

Plan on running sub 12# of boost, nothing extreme, sub 600 hp. on a budjet so that why i was considering just 4 bolts in stead of splayed. Of course the splayed is better but i was just going to use 2 bolt. so i think stock 4 bolt conversion would be a good compromise. Im a being dumb?

 

Splayed isnt necessarily much if any better than straight, its more in the composition of the metal that the caps are made out of. A cap cut from one piece of steel will always be stronger than something cast out of iron. Thats not to say the factory straight 4bolt caps arent strong, they are much much stronger than whats on there now, but something making that HP level, especially under boost IMO spend the extra few bucks on some billet caps and you will save $ down the road, you can of course buy straight 4bolt billet caps, but that wouldnt save you that much $