Needing help guys i'm looking for a LT1 Corvette four bolt main block bare. One that has no cracks and hasnt been honed or zero decked or anything. I recently had my stroker completed and fired it up and it has compression in the water so it appears to have a crack somewere internally. If anyone has or knows were i could get a block like this for a reasonable price let me know.
Thanx abunch,
Josh

 

Good luck finding them... I just use 2 bolts and convert them to 4 bolts.

Bret

 

Probably got into water when it was clearanced for the 3.875 crank and rods.
It can be repaired.

 

i spayed main bearing cap is stronger than a stock 4 bolt anyhow. if you already have a 2 bolt block in good condition, you will spend about the same for getting the new block.

Normal 4 bolt idea | | | |
Splayed 4 bolt idea / | | \

The angle of the outside bolts give added strength.

 

Depends.... on whether you are removing material that is critical to the block's web strength, when you bore the holes for the splayed bolts. One school of thought on the LT1... GM knew they were going to use straight 4-bolt mains, and designed the webs accordingly.

Just a thought.

 

Damn good point.
The General put them all straight for a reason. They could have put them angled in the design phase and they didn't-- wonder why.

I also was told to use bolts on the straight outside bolts as the ARP studs crack the webing. This from a guy that has done a lot of LT1 blocks.

 

This is the cap that I use on my 4-bolt stuff now. With this angle on the splay the caps have the most material to bite into because it's below the oil pan rail. This is also the same design used in the GM Bowtie blocks. I agree use the bolts on the outers.


This is what Fred (injuneer) is talking about with a cap arrangement. This is the easiest for GM to install and machine into the blocks. That's why I feel that they use this design. Remember GM doesn't need to make something that holds 600+hp it was only 300-330hp at the most.



This is the standard that most places use on a setup where a 2 bolt is converted to a 4 bolt.



Bret

 

I have to admit... most of my "info" is second hand, but the guys from Second Street seemed to feel the LT1 block was a lot closer to the Bowtie block design than to the Gen 1. While GM probably didn't anticipate a lot of very high HP applications, they seem to have built a bit extra into the LT1 block. And while a handful of successful 1,000+HP engines isn't conclusive, it does indicate that the LT1 is fairly reliable. And with one first-hand data point on a 1,000+HP engine using the straight 4-bolt design, I wouldn't write the GM setup off either.

I think there's something to be said for both designs. I run the Pro-Gram splayed caps (outer bolts), but I didn't get a lot of encouragement one way or the other from the shop that did the work.