I'm looking to convert my block over to 4 bolt mains. However my machine shop does not have the capability to do splayed main bolt holes, only straight. I ordered a set of 4 bolt SBC caps, but they do not fit right, and it appears they use a different style bearing (the notch isn't in the same place as stock cap) also the caps won't fit right because the appear to need about 5-10 thousandths shaved off the unbeveled part to fit in the LT1 block. Is there anywhere that sells straight LT1 4-bolt main caps anywhere? Stock ones would work fine from a corvette block if I could find them. Thanks

Bill

 

Any new cap will need to be "registered" to fit the block. But the caps designed for converting a 2-bolt to a 4-bolt are slightly different than those designed to "bolt in" to a 4-bolt factory block. I can't tell from your description which type caps you have. After this initial fittment, the caps will need to be aligned bored and then honed.

Lots of places to go for the correct caps. The last set I bought were from Callies. Just be sure you specify that you have a 2-bolt block you are converting to 4-bolt.

Rich Krause

 

Rich,

The caps I bought are a set to convert 2 bolt blocks to 4 bolt. They are a nodular iron set with the stamping MB-350-4B. I was aware that the Line bore would be required. Not sure what you mean by registering though. I took a few shots of the caps in comparison of the stockers.

http://www.bytehead.com/~dunk/3-27-04.html

I guess I was on crack when I said the bearings were different. The new cap just has 2 notches one on each side. The slots are the same on both caps. I just looks like the new cap will have to be machined a tad to fit right, maybe this is what registering is?
You can see in the pic that the width of the beveled area on the cap is only slightly larger on the new one. It looks to be close to 4 thousandths (thickness of a peice of paper) to large. Maybe this will help explain myself a little better? Pics always help.

Bill

 

Nice pic! You have the right caps, as far as I can tell. And those nodular iron caps are good. Same as I had on my previous shortblock, which had no trouble with over 700rwhp. It's normal to have to machine them, usually not more than 0.030" or so. They are made with extra material to allow for variation in the block. The machining for angled main bolt holes. It can be done with a hand drill, the proper bushing, and a tap.

I am not a machinist, but the above is pretty basic stuff. However, I wouldn't worry about the straight vs. angled outer bolts. As I posted above, I used what appear to be the same caps with no problems whatsoever.

Rich Krause

 

I know Milodon makes some ductile iron splayed caps for small and big blocks. Anyone ever try these? They come with a drill bushing so you can drill them yourself. But, the block will need to be align bored.