i bought the SBC today and i thought it was a 350 but as i get to looking at it i see the flexplate has a big weight on it and the balancer has about 4 holes drilled in the front. so im like hell yeah i got a 400. then i look down in the water jackets and the cylinders dont look symiesed. whats the deal here?

Originally posted by 300hp:
i bought the SBC today and i thought it was a 350 but as i get to looking at it i see the flexplate has a big weight on it and the balancer has about 4 holes drilled in the front. so im like hell yeah i got a 400. then i look down in the water jackets and the cylinders dont look symiesed. whats the deal here? -
Is it a 1 peice rear seal like 87 up?
They are externally balanced in the rear only

You might also have the potential for an easy roller cam swap. If you havn't put an intake on yet, look for a few tapped bosses in the lifter valley located right over the cam. These are for the lifter retainer "spider".
Good Luck

MaTt

no its old style older out of a 3/4 ton 4x4

So how did you look into the water jackets?? are the heads off?
What is the casting #

Really old 383? Before the stroker kit days?

yeah i pulled the heads off, ill get the casting numbers within the next couple days and post them and see what u think. or i guess i could just pull the pan and check that out.

if the heads are off you will see two steam holes between the cylinders if its a 400 if not its probably a 383 from the sounds of it

300HP,

The best way to find out with no questions is to
1- Look on the drivers side (left side) just under the head on the block you will find a block
ID#

2- Check the head casting #'s.

3- Go to the Mortec Chevy site. There you will see a list of all block and head casting #'s

Casting #'s don't lie. You'll know for certain
exactly what you have. Of course there may be
mod's that have been done that may tend to confuse you. That said, at least you'll have
some basic #'s to start with.

Through the years, I've seen soooo many mis-
matched parts on Chevy V-8's that it was a wonder that they stayed together :rolleyes:

its a 350 3970010 casting

300HP,

There you go! Got lucky on that one. The 310's
as we call them are great blocks. All 310's were
4in bore, 302 or 350 high nickel content motors.
Many were 4 bolt, but some 2 bolt as well. These
are heavy casting blocks. ( no Hencho in Mexico)

These motors were produced from 69 to mid/late
70's ( from memory ) Check the #'s on the deck
tab to be sure of your exact application.

If you are REAL lucky, you may a have 350 from
a 1 ton truck. Many of these had steel cranks
along with the 4 bolt mains.

Make sure to check the deck tab, you could have
a DZ/302. Wouldn't that be something. It would be worth mega bucks graemlins/thumbsup.gif At any rate, these motors are becoming non-existant because
of short track racing. They are drying up so everyone is holding on to them.

Good luck with it and take care of it.

Johnny,
If the flexplate has a weight on it, it is probably not a 350 or a 302. That might be what the original block was used for, but certainly not what it is now. SOunds like an externally balance 383 to me.

Originally posted by Johnny B.:
300HP,

The 310's as we call them are great blocks. Just curious, who is "we" and why do you call them "310's" ?

Dean,

" 310 " is just short for 3970010 - first#3
last two #'s 10

(We) is a group of friends/builders/racers here
in South Central Pa who are using all of these blocks we can find.

BillK,

Yep, I agree with you. I did tell 300HP
to check the block #'s to determine what size/application and to also check for
mods as well. You and I both know that
every conceivable mis-matched part can
be bolted on a Chevy V-8. No doubt you
have come across motors that have the
wrongbalancer and/flywheels. These guys
wonder why their teeth fall out when
they approach 3000.

Sounds like 300HP may have a 383, then
again he may not. One thing for sure,
he has a decent block if all else is
right.

look for the 020 numbers cast in the timing chain area for a high nickel block, 010 blocks are an easy find in my area, how much are they worth down south?

010 is one of the most common of all the 70s 350 castings. Just look in old pickups, there's a very high probability it's a 010.

Never heard that casting called a "310". I guess after 30-odd years though, people can make up all sorts of stuff. We've all been calling that block "010" since the early 70s, and last I knew (oh, about .... yesterday evening) that was still the prevailing designation for most people.

But, as mentioned, alot of them (being truck blocks) came with 4-bolt mains and a steel crank. It's getting tougher to find them laying around in unmolested factory configuration though, being that they quit making them about 25 years ago.

Since you have the heads off turn it over until a piston is at top dead center, make a small mark with a marker then take it to bottom dead center, measure and youll know what your stroke is.

The "3970010" number is the casting number for a 302/350 block. It may or may not be high nickle. Look under the timing cover for a 010 or 020 or both. The 010 under the timing cover means it's a high nickle block. The 010 part of the 3970010 number does not mean it's a high nickle block but it could be.

Do like Nickel said and measure the stroke, you don't need to be exact. What is the harmonic damper like? Maybe they put on the wrong flexplate.

the balance looks different than my old 355 i had. its wider and has 4 about 7/16 holes drilled around the edge. the motor looks bone stock. also about where the filter screws on the block it says 010 then under it is 020. im pretty sure thats casting content too. so it looks like a good nickle/tin block.

I just picked up one of those blocks for 25 bucks a month ago. Complete 4 bolt shortblock with standard bore and very little taper. They are still around if you are in the right place at the right time. I'd still prefer a one piece rear main 350.

The nickle/tin content is notated under the timing cover.

I'm glad 350 blocks are easy to find in your area. Around here they are getting very hard to find.

any one know about how much these 3970010 blocks are worth I have two one with the 010 and the other block with 010 and 020 casting marks. and yes i got them both from a circle track racer.