Main Caps Loose in Registers

[SilverFox]

I have a 4 bolt 350 Chevy block that the main caps are rather loose in the registers. So loose in fact that you can seat them completely by hand with very little effort. There is no visible sign of previous cap walk (ie. welding or metal transfer). I have two questions.

1. Can/should this block be used for a 480-500 HP drag race application?

2. Is there any fix for this loose cap/register issue, if so what can be done?

Thanks,
Tony Naquin

[Alan Roehrich]

I have a round nosed steel drift, the tip is about 5/16" diameter. I take a 6# hammer and the drift and stake the caps in with about 4 hits on either side. You want the edge of the stake mark the drift leaves about 0.020" away from the edge of the register. I always do that before align honing a block as well.

[needforspeed66gt]

When you take it in for an align hone, just point out that the register needs to be fixed(they should see that themselves) and they will fix it. We use a round nose wide width punch to fix.

500rwhp in a drag application will put some load on the crank, I tend to go for ultimate strength and in that application would go with a 2 bolt block and convert to splayed caps.

[jake197000]

i have the sunnen cap knurling tool and it works fine.have done it both ways though

[PackardV8]

So loose in fact that you can seat them completely by hand with very little effort. There is no visible sign of previous cap walk (ie. welding or metal transfer). Thanks,Tony Naquin

Some would question whether those are loose or just not as tight as some others.

[rebelrouser]

I go back to the old, how much HP was the block designed for? Me personally when I want to build an engine with a stock block and I am going to go a lot over the designed power level, I sure don't want to start with a block that has damage. And loose registers to me are damage, the block has seen enough stress to loosen the registers, so will it take a 500hp level build? I have had stock block registers repaired for a stock rebuild several times, I gave the customer the option, but I never recommend it. The block is the foundation for the entire engine. If an old house has a weak foundation, there may be multiple ways to repair it, but how many carpenters would build a new house on a damaged foundation?

[miniv8]

Broke a stock front cap once. in a 3970010 that already had splayed caps.
Race coming up and the one cap I had was way off to the side.
I tig welded stainless seam on one side and filed down the other register to move the cap to align with the main bore.
Worked like a charm. In fact, later I ended up milling that cap flat and lay on top of it a flat steel bar so It wouldn't break again. and it hasn't.

On a rebuild I have staked them like Alan describes.

[Dan Timberlake]

Depending on how loose, I'd say staking to tighten register fits needs to be done with a bore gage close at hand.
My concern is inducing "cap shift" of .001" or maybe even more.
https://encrypted-tbn0.gstatic.com/imag ... Q&usqp=CAU

With modern bearings the insert is thinned at the parting faces.This makes it hard to create a big problem, but centered is better.