Agreed , taking anything off the cap could change the hole in the cap/block

And John your the one that split a block... 2 hits
with a file on both sides isnt gonna change DICK
and you guys are acting like this is rocket science
and its not.. I've seen plenty of machine shops do a
ton of stuff that some wouldnt do and they turned them
9000 rpm and .... they lived a long time

At Pettis it was common practice to hit the main saddles w/a fine file.......

My new favorite quote!

I've seen it done many times even after the bore
was done.. because they had to much of a problem
getting the caps on

Do you really think 275 (8 second) runs with a stock 440 block was a BAD thing. I was very very happy to get that many passes out of a stock block at that HP range. Heck that would last most of you guys a life time. LOL

It might last some a life time... I tend to spin
them up even stock blocks... LOL and I was in the
8s with my junk

Smoke em with an angle grinder and you'll be able to throw them on from a couple of yards.
No issues installing or removing them

Put the main Capps in your freezer over night, and let the block sit in the sun....

Yep... but most dont do that... IF they are lucky
they do the work at room temp.. I had a guy teaching
me on machining that came from NASA.. it told me that
5* was the limit for there work.. then it went back into
a temp controlled room... so that junk took for ever to
machine(with a ton of cutting fluid on the part)

Do you really think 275 (8 second) runs with a stock 440 block was a BAD thing. I was very very happy to get that many passes out of a stock block at that HP range. Heck that would last most of you guys a life time. LOL [/quote]

It might last some a life time... I tend to spin
them up even stock blocks... LOL and I was in the
8s with my junk
[/quote]


Not picking here but did you ever run a stock big block? And how long ago?

It might last some a life time... I tend to spin
them up even stock blocks... LOL and I was in the
8s with my junk
[/quote]


Not picking here but did you ever run a stock big block? And how long ago? [/quote]

Back when I ran a destroke 383.. big rpm engine
then a couple of years ago I bought a mega, new
Callies crank, and B1m/c heads.. but I ended up
selling all that stuff.. again that was gonna be
high rpm (9000+)

Watch what this guy does at 4 mins into this clip.

https://www.youtube.com/watch?v=e3r3wRBoXkk

The last KB aluminum block I worked on had steel main caps, isn't that thier stock standards now I'm almost postive that all the after market race hemi aluminum blocks some with the main caps tap for using a slide hammer to remove the main caps

Ya he deburrs the block before the line hone on a chev.
And the point is you need to know how to machine a chev??

i am no engine builder, although i have assembled quite a few over the years, all makes[even an import] and sizes. it looks like the OP is using bolts, thus having difficulty starting the caps square. in situations i have encountered over the years when mating of parts together must be square, i cut alignment dowels from a couple of old bolts and thread them into the holes, mate the parts together, then remove the alignment bolts and replace with the intended fasteners. this may be something the OP would want to consider. just something i would try before going to more drastic measures. your results may vary....

Can you measure and see what interence is? I'd try chilling them first and heating the block. If it's to much of an interence fit then carefully flat filing each side and carefully measuring to make sure you take an equal amount of each side would be okay.
What kind of an interference do caps usually have with the block? .002"?

Closer to .001... at .002 your gonna need a press

II have .02 difference between the cap and the block. The caps are in the freezer and I am going to check again in a while.

I really appreciate all of the good advice and information from everyone!

.020 is huge... you might mean .002.. and thats tight