Technical SBC Identification

For my 54 GMC project I was given a old SBC and a TH400 to keep my project alive.

Date code F158 so June 15 1968



Casting number 3970010. Usually seen on 350s yet a 350 was not available in 68? So 327????

Serial and Vin Code

I know it's a Saganaw Cast due to the clock. Shift 1 7 hours in to the shift according to my Chevys By the numbers.

The T8 on the serial tells me T= Truck and the 8 again for 68.

Has a huge Harmonic Balancer and and equally large and pushed forward crank pulley




Heads gave slightly angled plugs and rounded square ports on the exhaust.

Has an aftermarket intake, has not had a vlave cover pulled yet to get head casting.

The T?S is confusing is that a D or a backwards C? Nothing I have found notes a TDS if it's mis stamped.

Also having the stamp above and below is not like any I've seen, usually it's all along the edge in a line.

I know it's not a 78 motor as again according to my book in 70 they started stamping 70,71 etc to note the year not just the last number.

The 3970010 is equally strange being a 68 block.

Far as I can tell this might be a Large Journal 327 C10 motor??

What says the actual experts of the HAMB?

Unknown what it really came out of as buddy who got it rescued it from a crashed SBC swapped Jaguar.

All I know it's no DZ. Lol!!!

 

1978. Not 1968. The two digit year on the casting date was a random thing, you can find single or two digit years over several decades.

The short number pad is a big clue that it's a later 010 block, not an early one.

The three letter suffix TDS is another big clue, they started using three letters in 1970, and most of the Chevy cars started with C, most of the truck motors started with T. This is a GMC engine, since the first character of the partial VIN is T, not C

 

Thanks Squirrel so it's just a run of the mill 350? At least it's a GMC motor going in a GMC.

 

I've got it's twin out in the garage, At least the short block. Came out of a 78 truck that my buddy horse traded for to get some part out of and I got the engine that I did a rings, rods, mains and valve job on.
Then I wore out again and this time it needs a full rebuild.
The big damper is a good thing, don't toss that out.

 

Any clue if it's a 4BM? Probably just a 2BM but one can only hope.

 

Actually the 350 was first introduced in 1967 for the Camaro SS.

 

But not with the 3970010 casting? I should of clarified.

Also nice Deuce HB. Old man built a 29 HB roadster back in the early 90s. Scratch built the frame to be different.

 

Most of the truck 350 010 blocks were 4 bolt mains. If you care, drop the pan and see.

 

Yep! I'm curious also....
Pull the pan please.... And post a picture er 2....
You might even have a forged steel crank if your lucky...

 

Be a while till I can get the pan off. Not looking for a crazy radical build but 300-325 horses will make me smile. Open 9" diff or I'd go crazy, bit it is a big bearing 31 spline big axle 9".

 

I'd put the odds of 4 bolt at 95%, and the odds of steel crank at 5%

 

When I worked in a parts store that also had a machine shop in one end of the building, someone bought a rebuilt 350 for their '72 C60 truck, and when they dropped off the old engine for a core, I was thinking, "Great! I'm going to latch onto that one and get a forged crank!". Ran the numbers...and it was originally out of a '70 Impala with a 2 bbl and a Powerglide.

 

Head stamping

 

that last picture shows why you should not use gaskets with manifolds on chevy engines...

624 heads are pretty crappy, as chevy heads go. But they'll work ok if you're not too worried about performance.

 

I have read the heads are prone to cracking. So I am probably going to have to find some aftermarket heads if I want reliable power.

 

@squirrel eighten me on the gasket thing. Truly curious as you are not the first person I've heard that from over the years.

If all goes forward on this and it will thisotor will probably now end up with some decent low end heads and long tube headers or at least some block huggers.

 

Chevy didn't use gaskets between the head and manifold. They're not needed, and all they do is insulate the parts from each other, limiting heat transfer, then the manifold gets too hot, especially between the center exhaust ports.

but gasket sets come with the gaskets, so people install them.

Headers need gaskets...

 

Fords also did not use exhaust manifold gaskets, somehow I got the idea to use graphite grease as a sealer.

I think a lot of broken manifolds can be traced to the use of gaskets, and the uneven disintegration of those gaskets combined with retightening of the bolts.

 

Best to have the surfaces decked of you rebuild and plan on running manifolds vs Headers?

One shop project we got a set of Hedmanns and could not get the things to seal even with those thick heavy gaskets. It would blow them out in mere miles. Found the flange was nowhere near ture for brand new. They wouldn't swap them out since we installed them. Tried to have the face decked but they couldn't get it in the machine. I did my best to flatten it but ended up taking a slab of 3/4 plate made a jig heated the flange cherry red and bolted it to that slab of steel. Let it cool over the weekend. Never had an issue again. Other than you can't keep paint on the dang things even high temp. Lol

 

I have basically that same engine in my 52 GMC (see avatar), although out of a 76 truck. It runs fine, reliable as a rock, only leaks a little bit of oil. Old Edelbrock dual plane alum intake with a Q-jet and rams horn manifolds dual exhaust. The heads are not the best for performance as noted, I keep debating myself to upgrade to better heads, or just go with a whole 383 new engine. The 383 would have better power and be roller cam to eliminate the oil issues. But for now, I drive all over the place and it is tough to beat a good running old 350. While needing to do work on my other old cars.

BTW, no idea if mine is 4 bolt main or steel crank. Never looked inside the pan, or paid enough attention to the crank flange when installing it about 12 years ago. It was a good running engine that was available to use, so it got chosen to be put into the 52 GMC.

 

Well I got one upped today. With all the questionable stuff on this one. The buddy that was giving me its uncle is giving me the 350/255 HP WK serial suffix crate he pulled from his 3/4 ton C10. With an equal mileage Turbo 350. Both are supposed to have less than 10k miles on it. Not a thing wrong with it other than he wanted a 396 in the truck. So I now have a guaranteed running motor for the truck. One that doesn’t puke oil out of every sealing surface. This one will be clean it up paint it my color and drop it in. Hydraulic flat tappet cam motor. Supposed to be a 4BM so mods can come later. It will get my Wieand Dual Plane intake and my Holley Carb. And my valve covers I have stashed away.

get healed from my surgery and get things done.