1968 396 High Torue - What's inside of it

[AnotherWs6]

My 68 Burb is still running the original high torque 396. What kind of internals did these have? I'm talking pistons, rods, crank. Head cc?

[vectorit]

Pretty much an L-35 configuration with 325hp.
Semi closed chamber iron heads, with big oval port intakes.
Domed cast pistons, 10.01 comp
standard cast rods
cast crank
2 bolt main block
4 barrel carb, cast iron low rise intake.
Painted valve covers

I built one of these L-35's to perfect stock spec when I was restoring my burb with the intention of going with it instead of the original 327, but later decided to stay the course and restore my burb to the way it came from the factory.

[AnotherWs6]

I have the original heads in my basement, they look normal to me. Not sure what a "Semi" closed chamber looks like tough.

So not exactly a heavy duty truck motor huh? Just cast crap everything.

[vectorit]

Pretty much.
The 396 stopped coming standard with a steel crank in 1966 I think.
The heads are, or were valued by street racers since they made good compression.

[Alex V.]

Originally Posted by AnotherWs6

I have the original heads in my basement, they look normal to me. Not sure what a "Semi" closed chamber looks like tough.

So not exactly a heavy duty truck motor huh? Just cast crap everything.

Unless I'm mistaken truck 454's were cast crank up through the 80's and they weren't slouches. Not exactly a head start on a drag engine but I think you're doing something wrong if you tear one up in any kind of normal use.

Documents for '68 trucks show compression at 9:1 (10.25 for El Camino Turbo-Jet) and gross output for 4bbl. version being 310HP @ 4,800RPM, 400 lb.-ft. @ 3,200 RPM. It also says forged crank and rods.

All that information and more was found here starting on pg. 107: https://www.gmheritagecenter.com/doc...olet-Truck.pdf

[AnotherWs6]

Thanks. I see it does list forged crank and rods in the spec boxes. But in the literature before that it says that the 366 and 427 got forged stuff. Maybe that means those two sizes werent forged before.

It also says domed pistons, which makes sense because my heads appear to be normal, open chamber heads. If they were closed or partially closed I don't think domed pistons would be creating 9:1 ratio, and of course wouldnt physically work if fully closed.

I'm asking because aside from general curiousity I would also like - I have another thread about this - to put a small, single carb supercharger on it. So it just got me thinking. If it were 10.5:1 and all cast stuff......