Getting a list of things together to put together a 400 based 511/512. Was looking around for main cap/girdles. Has anyone use the 440source kit of billet steel caps and girdle? Any fitment issues? I also see Milodon has Ductile Caps, the 3 middles ones or a set of 5. What's everyone using and liking?

I expect you'll see a number of recommendations to go with aluminum main caps, instead of steel or ductile iron. I like the BCR caps, although I don't recall them being available when I had a different brand of aluminum caps installed on my "next build" block.

Lots of different opinions on the benefits of using a girdle, too. I think the combination of aluminum caps and a girdle makes sense, but not everyone will agree with me on that.

The plan is to build it with around 10.5:1 compression, Steel Rod, Alum head and not rev it past 6500. Will be a race only engine, but going to try and build it fairly mild so it last for a long time. Not sure how that affects how crazy I should go with the main caps and girdle...

If I was going to get new main caps for a stock block, they'd be aluminum.
I don't think the strength of the caps themselves is an issue, but softening the blow to the bottom end of the block is.

The center 3 caps on mine are billet steel. Mine makes 838 peak and 776 average.
How long it will go like this I am not sure?
This current block in other configurations has over 300 passes on it. With the current configuration it has 54. So far so good. Will it fail someday....... Probably.
If a guy could get his hands on an aftermarket block that would be best. But for now this is what I have to work with.
I keep my fingers crossed everytime I let go of the button LOL.

we have the bcr caps and girdles available. we sell tons of them over seas as well as in the states.

I used a girdle with stock caps w/studs in my 440

Milidon does not sell the Ductile iron caps now
Do NOT use steel caps on a cast iron block
I like and use to use ductile iron main caps on all my builds over 600 HP when I could buy them, now I use 440 Source aluminum with main studs, no girdles
I wish that we could buy good blocks with four bolt main caps and thick cylinder walls

Cab,
Are you referring to P/N: 11361 (3 center caps) and P/N: 11365
(all 5 caps)?

Milodon still lists them on their website, Jegs and Summit list them as well but both have an expect delivery date in Dec...Doesn't mean they are available, but looks like they still make them, maybe.

FWIW, I run past 7000 r's on stock studded caps and have for 15+ years............

I called Milidon several weeks back to ask if their center ductile cap where machined for the thrust main bearing now, I had bought some years ago that where not machined for that bearing. I was told then that they are steel now, not ductile iron

I have the 440source aluminum main girdle kit. Works very well. I have never had an issue with it. I drove it on the street for 2 years. I took it in to get freshened up, and everything still looked great!

I use 440source aluminum caps with studs as well. No issues yet. I do like the look of Jerrys caps better. They look to fit the block better imo a better design.

Do NOT use steel caps

Why ?

Street motor with around 500 HP that will never see the track or 6200 RPM's

I bought (and still have) a set of Milodon ductile caps for a 400. The main bearing opening was machined for 440 size. No go. I have run steel caps and studs for ~15 years w/o issue with one freshen. Around 590 HP.

I am running the BCR aluminum caps and girdle, nice stuff, it's up and running and all seems well.

I have Best Machine aluminum caps and ARP studs in my 500. But for the power and RPM you will be running, I don't think that any of it will be necessary. My old 440 made 575hp, launched at 5,000 rpm, shifted at 6,800 rpm and went over the traps at 6,500 rpm for many years. Never any problems on original caps and bolts.

BRC alum caps and stud griddle on mine too. VERY nice set up (read; NO SHIMS!)
Good luck with yours, Brian

Steel expands at a different rate than cast grey iron does, same thing on aluminum main caps, the expansion rate and holes in them do not expand the same as the cast iron does
Hence my preference of using cast ductile iron
I had three RB blocks with cracked main webs
The 400 blocks are way better to start with than any OEM 440 block for any build that you want to make more than 600 HP on pump gas or above 650 HP on race gas

You had 3 crack where others have had none,something going on there.