identify 400 small block chevy

Hey BJ the fast and easy way is to feel the side of the block it is slightly pregnant. there is a slight bulge between the water jackets. A 350 is flat in this area. I can tell one when it is still in the car. Stop by the shop sometime We have some bare blocks that you can look at. I messed up and sold the 35 ford Pk i bought from you. Randall

 

Ah, you can see the bulges clearly in post #23. Thanks

 

$#$#--- I have been building race engines for over 30 years and I would like to see a stock block 454 small block turn 8250 RPMs for any period of time without exploding into a million pieces ??? >>>>.

 

OK lets let the learning continue. Can you use a 350 head on a 400 SB???

 

I have, with no drilling of steam holes. You'll hear all kinds of "why nots", and I'm cool with that. But, I've done it with no probs. I'm not saying you "can", I'm saying I "DID"

 

not hard to drill the holes anyway.

 

I race circle track open wheel and sportsman so with the 3.75 crank 5.7 rods I try not to go over 6ooo rpm. On a claimer with the 5,5 rods I kept below 5300.. With the 3.48/ 3.5 stroke 5.7 or 6 inch rods about 6800 to 7000 tops and the one with a 3 inch stroke 44 lb crankand 6.125 aluminum rods and really big valves I like to stay around 7500 some times I turn a few more with the short stroke. I stay conservitve as I have no money sponsors........................................Yes you can run a 350 head on a 400 block. You will have to drill matching steam holes. I use a head gasket as a template.

 

externally balanced, 400 small blocks were the only ones I believe
I certainly hope no one actually does this unless a last resort.

not at all. FWIW most aluminum head manuf. only suggest that the two lower on each side be drilled.

 

tooth count doesn't mean much as far as a 400 or not.
tons of internally balanced oem 168 tooth flywheels/flexplates.
it's the weight on the flexplate that makes the difference and it's NOT the same weight as a 454 although it'll bolt up.
also ain't the same as the 1 peice rear main small blocks that have the weight on 'em.

 

www.mortec.com
JimV

 

I think it's a bit more involved than just using the head gskt as a template. I believe those holes need to be drilled on an angle in order to intersect with the intended water jackets

 

You dont need the steam holes,i always block them on the deck to stiffen it up and keep from blowing head gaskets.

 

You dont need the steam holes. Fill them with epoxy. I put 350 cranks in 400 blocks using spacer bearings. I knew a guy that put a 283 crank in one It would turn 10 grand all day.

 

Steam holes.. As mentioned, you only need one set, check out online pdf instructions for edelbrock RPM heads for a nice how-to guide on drilling your head.

Blocking them or not using them at all- common in the race world. Those guys also turn major RPM, thus the water pump is really pumping.

Steam holes exist for low speed, when the pump isn't pumping like crazy. Such as running hot in slow cruise traffic. Once you ruin the ring temper in a spot or two, she'll be a smoker.

SBCs have enough overbuild that you can probably run no steam holes without issue. Most of the time. But why? Sharp bit, centerpunch the hole, double check on the gasket before using a hand drill. 20 minutes tops, the ole lady will barely notice your hand is off her boob before you're back on the couch watching Falcon's Crest.

 

Yes there are 168 tooth internally balanced engines available, but they all look like ls1 v8's. Ive never seen a factory 168 tooth internally balanced flexplate/flywheel.

As for 86+ 1 piece rear main engines, I think the center bolt valve covers would be the obvious indicator. If these had the 168 tooth count, I'm not aware of it.

400's production from 70-76 and still available until 1980 in trucks and vans, so keep an eye out. I personally like the 2 bolt over the 4 bolt main blocks. I was told they are just as strong if not stronger. I get 2 bolt blocks for half the 4 bolt because the salvager thinks they are stronger.

 

There are several different 400 castings and some have the same casting number but are obviously different.

I have an 817 casting 2 bolt 400sbc I am building now, and my engine builder has a bunch more 400's. Here is what I have seen:

All 509 casting 400's are 2 bolt mains. These usually have 3 core plugs. Some have only 2 core plugs drilled but have the bulge for a third. Some early ones don't even have the bulge. This is the strongest factory 400 block. These are all early 70's castings.

All 511 casting 400s are 4 bolt mains. They like to crack at the outside bolts in the main webs. I have only seen a few of these and they both had 3 freeze plugs. These are all early 70's castings.

The 817 casting blocks are all 2 bolts, and every one I have seen including mine, has three core plugs. This is the second strongest block from the factory for 400's. These are the later 70's castings and usually found in trucks since they stopped using 400's in cars in 76'.

I have heard of another casting number but never seen one.

 

the block bulge is the sure way to tell. worked for a major engine remanufacturing company and the guys on the line used that method,much quicker when you tearing down 130 motors a day.