Cross Bolt Cap Crush

[ProPower engines]

Hey guys
Working on an old cross bolt Hemi block and the OE caps disappeared over 30 yrs storage apart.
I have several sets from other projects but Does anyone know the crush spec for the cross bolt area.
They are similar to a cross bolt 390/427 ford just larger main caps.

I have to line bore a set of used stock caps so I have to add material on 1 side of the register but want to avoid
too much interference at the side to create a distorted cap before it goes back together.
I will be using ARP's fasteners for both the center and side bolts.
Some stock caps just slide by and others are about .0005" tighter.This block had a window repair so adding undue stress
to the block would not be good as it will be a driver and show piece mostly

Any suggestions where to locate info on this would be greatly appreciated

[Kevin Johnson]

Not official but a suggestion by engineers in a Ford patent: 10 to 200 microns for the register (then see below).

http://www.kylesconverter.com/length/microns-to-inches

l 5 The bearing cap 14 has a pair of lock width surfaces l 8 precisely machined thereon that in use co-operate with the surfaces 17 on the block to precisely locate the main bearing cap 14. The bearing cap 14 is secured in position by vertical bolts 21 and cross bolts (not shown) which screw into a raised pad 22 on the side of the bearing cap. The cross bolt pads 22 are machined to always be in clearance with machined location surfaces 23 on the block so that the lock width always provides the interference between the bearing cap 14 and the block 11

[MotionMachine]

I think a slip fit is all they want, no interference. 427 Fords are that way and Ford varies the thickness as needed then marks their position. I put 3 aftermarket caps on a hemi and the caps were made wide so that you can fit them as needed. I had to take material all off one side of all the caps just to get them between the bottom registers and at that they just barely cleaned up at the parting line when I bored it. This left clearance on the opposite side of the top register so I made spacers that were captured in a pocket I bored around the bolt. Then I could grind spacers to the needed thickness for each cap. Time consuming but the spacers would only have been about .015" thick if I just put them between the block and the cap but I could make them about .125" thick with this method.

DSC00549 (Small).JPG

[ProPower engines]

Thanks guys.
I thought it was not really an issue with the upper support bolt clearance more then just a slip fit.
The stock caps that I came up with will work out but the thrust cap was my main concern to have aligned perfectly
to avoid any bearing issues. Again a numbers deal and since using a aftermarket cap would have made this much easier
customer insisted on using a set of stock caps as part of the repairs to the block.

Thanks again

[RW TECH]

Current configurations (like GM LT1/LT4) have small amounts of interference at the cross bolts....About 1/2 as much press as the bottom register (.002" top, .004" bottom).

This reduces stress in the skirted area and it's a better idea than "preloading" the block by pinching the skirts into the caps.

A lot has been learned since the 60s' when it comes to things like this.

[Kevin Johnson]

Current configurations (like GM LT1/LT4) have small amounts of interference at the cross bolts....About 1/2 as much press as the bottom register (.002" top, .004" bottom).

This reduces stress in the skirted area and it's a better idea than "preloading" the block by pinching the skirts into the caps.

A lot has been learned since the 60s' when it comes to things like this.

Yes, that's true, the Ford patent was circa 2003.

[ProPower engines]

After all the fitting I ended up with .003''-.004'' on the main registers and .0015" at the skirt.
When at arp's 45 ft Lb torque spec they are tight. I felt that would be better then forcing the block skirt to flex more then required.

Thanks again