Hey guys I have been looking for a SBC 400 to build a motor with and have found some decent cores.

The only standard bore 2 bolt main block I have found so far is missing the 3 center main caps. He only wants $20. I talked to my machinist (who owes me money) and he will drill it for splayed 4 bolt caps line bore it for FREE to balance out the debt.

Here's my question, I see splayed 4 bolt billet main caps all over ebay all day for cheap. I have considered going this route since it will bulletproof my bottom end. However I have heard that using billet main caps causes the main bearing to wear quicker because of the different expansion rates. Plus I should add that I would be using the stock 400 front and rear iron 2 bolt main caps.

The motor hardly needs this much bottom end, but finding 3 stock center 400 2 bolt main caps might be just as expensive as the new billet units off ebay. It would have to be line bored anyway, so the cost is about the same either way.

Any thoughts are welcomed and thanked.

I think the sences is to keep the 2bolt when using 400 blocks.

Originally posted by supersport396_2000:
I think the sences is to keep the 2bolt when using 400 blocks. Why is that? I have heard that normal 4 bolt main 400 caps are not a good idea because of the main webbing.

However a splayed cap doesn't come near the weak areas like a straight 4 bolt cap does.

Please correct me if I am mistaken.

I would say to jump on it in a heart beat. I
have several two bolt 400's and all of them have
their caps but I am looking at building a high
horse out of the next one and will be doing the
center three with billet splayed caps.

Originally posted by SS70SS:
I would say to jump on it in a heart beat. I
have several two bolt 400's and all of them have
their caps but I am looking at building a high
horse out of the next one and will be doing the
center three with billet splayed caps. Honestly if I found a complete set of 5 2-bolt caps (from the same motor) I'd prob just go that route and use main studs.

Change of subject a bit. I starting wondering why it is missing its main caps. Plus, I found out that the block hasn't been mag'd. The owner says he bought two 400 blocks a few years ago, one had the main caps and the other didn't. The one with the caps was build and is still running in his work truck. The other has just sat until now.

I know a mag' check is the only way to be sure that the block is crack free, but are there any obivious spots I should look for cracks before laying down the cash and spending the extra money for hot tanking and a mag check?

not only have it magged..but have it sonic checked too...the cracks usually start at the head bolt holes and go to a water jacket. I just bought a 2 bolt 400..it had NO main caps

Originally posted by bigjimzlll:
not only have it magged..but have it sonic checked too...the cracks usually start at the head bolt holes and go to a water jacket. I just bought a 2 bolt 400..it had NO main caps Did yours turnout crack free? Thanks.

I got real lucky..no cracks and its very thick..all but one cylinder sonic'd out at .230...#5 was .190 on the thrust side

You and SS70SS might get together and you pick up a set of four bolt mains off ebay and swap them for the two bolt mains he has.

Then have his PROFESSIONALLY fitted to your block AND I bet both of you would be happy!!

Food for thought???

pdq67

Originally posted by pdq67:
You and SS70SS might get together and you pick up a set of four bolt mains off ebay and swap them for the two bolt mains he has.

Then have his PROFESSIONALLY fitted to your block AND I bet both of you would be happy!!

Food for thought???

pdq67 Sounds like a plan, what do you say SS70SS? (real name?)

I bought it this morning guys.

I did a quick pass for cracks, etc. and everything looks good to the naked eye, I guess the machine shop will tell if this was a good buy or not.

[/qb][/QUOTE]Honestly if I found a complete set of 5 2-bolt caps (from the same motor) I'd prob just go that route and use main studs. [/QB][/QUOTE]

Cable,
If it has the front & rear those are the ones you want to use. It makes life much eaiser to do the center three if you have the original ends.
Also, I may have a set of stock ones floating around here if I haven't thrown them out that you can have for whatever it costs to send them to you.
email me if you are interested & I will look on Monday.

The stock front and rear caps that came on the block are from a 350, so they won't work either.

So, it looks like I will need all 5 400 caps after all.

If you have all 5, I would be more than happy to take them from you. Thanks for the offer.

I would be interested in doing something like
that if you can not come up with a set of caps.
By the way my name is Kevin.

By the way whatever caps you and I come up with,
they will have to be fitted by a shop, it will
cost the same for stock or billet caps to get
them fitted.

I got alittle more if on the block after cleanup.

It came from a '74 Impala according to the VIN on the deck surface.

The block was cast in early of October of '73. It has the 010 and 020 (tin and nickle) marks under the timing chain area. The casting number is 3951509. It is missing the "middle" freeze plug or the "raised" area like some 400's had.

The rear main cap cost over 200.00 for billet..ouch..

Cable,
If those front/rear caps are BOLTED to the 400 block------------------THEN, WITHOUT QUESTION, THEY ARE 400 CAPS AND NOT 350 CAPS!!!!!!!!! You CANNOT bolt 350 caps to a 400 or vice versa, BECAUSE the bolt spacing is different!!!!!!

Also, for $20, you can't hardly go wrong----------UNLESS there is a BIG hole in the side of the block, then it's a boat anchor. When was the last time you bought an anchor for your boat? It probably cost more than $20! Ha!
So, I say, get off the computer and GO GET IT!!!! It may take a while to locate a set of good used main caps, but, so what. They will turn up eventially. You're right about a 2bolt SB400 block being a better choice. Build it with main studs, or, install splayed caps. Yes, I do have, and have built for others, several 4bolt SB400 engines. But, that was before I became convinced that the 2bolt version was the way to go. In my family, there are four 4bolt SB400 engines (one is bored/stroked to 420). NONE OF THEM have ever had a problem!

I already bought it yesterday Tom, no worries.

The caps that came with it weren't bolted to the block. That's how I knew they weren't correct when I tried to line them up..

Originally posted by DZAUTO:
It is likely this would be a good starting point for a healthy SB400. Also, if you got the heads to go with the block, they would be good for building into a set of nice street/performance heads (as long as they do not show any signs of being severely overheated). Generally, 70-74 SB400 heads are among the best FACTORY SB heads. The LAST year for good, factory SB heads was 74. In 75, they started cutting corners and lightening the SB heads by casting them thinner. The 74 heads were the last of the thick, heavy heads. If you DO have the heads, and want to use them, DO NOT have them surfaced if they are good and flat and not warped. A quality SB400 head gasket will seal them up just fine! The reason for not having them surfaced is to keep the head surface as thick as possible.

The 70-74 SB400 heads can easily be opened up to accept 2.02/1.6 valves and with MILD port matching and pocket porting, they will make you an excellent, budget head. If you plan to use a cam with over .450 lift, also have screw-in studs installed. I plan on using Pro Topline heads since the stock castings weren't there for sale.

I have another question kinda related. Is it okay to have my block deck surfaced? I don't plan on ZERO decking the block or anything. I just wanna make sure the block surface is flat and no worries about head gaskets.

Does anyone see any problem with this?