anyone know anything about this 76cc head [Archive] - Chevy Nova Forum

: anyone know anything about this 76cc head


Mustangsaly
8th-April-2007, 03:08 PM
I have a 76cc 350 gm head # 3970128 but I can't find the number on mortec or any where. I've came across the # doing a search on google so I think it must be the right gm #. I looked at the # on the heads last time I seen them, so I'm sure thats the right # (but the heads are in my storage or I would just look at em again) I don't think there anything special, but they are fresh w/ new comp springs and retainers and 2" stainless intakes and 1 1/2 stock exhaust valves and screw in studs. The intake ports are gasket matched and the chambers have been polished. a friend wants to buy em so I was after a little info on them. anyone have any idea what there worth ? I bought them for a stroker project that never has happened yet, and I think paid around $200 a few yrs a go but don't really remember for sure, as since I bought a set of 492s with hardseats that were left overs form a machine shop and a set of salvage yard 062 vortecs.

thanks for your help





Mustangsaly

patman
8th-April-2007, 03:20 PM
I did a google search and came up with this for sale ad...not sure if the info is correct, but...

SMALL BLOCK CHEVY HEADS cast number 3970128 from small block 400c.i

Mustangsaly
8th-April-2007, 03:39 PM
yeah not a lot of info huh ? there fresh 76cc heads though. and could build a nice 325 or 350 hp SBC with them is what I was thinking...........




Mustangsaly

stock z/28
8th-April-2007, 06:34 PM
Hello,

Are you sure its not 126?

Are the spark plugs tapered seat or do they use a gasket?


Jeff

Mustangsaly
8th-April-2007, 07:24 PM
no there not # 126 but i'm not sure as I've never run them yet. but I think they looked just like another set of 76cc heads that were off a 71chevy p/u.

Mustangsaly
8th-April-2007, 07:29 PM
what do you mean a gasket ?

stock z/28
8th-April-2007, 09:52 PM
Hello,


The older style spark plugs (used to be a 13/16 hex) used a flat surface and a gasket, this was used (generally) 1970 down.

71 up generally used 5/8 hex and a tapered seat as a seal, without a gasket.


The reason I asked is that is usually an easy way to get a guess in the general "era" of heads. There was head that ended in "126" that was very similar to what you have that was used in 69-70. It was kinda like a 441 casting.

Jeff

Mustangsaly
9th-April-2007, 02:15 PM
I will relook when I get back to storage cause maybe they are 126s huh ? 126 a bad sbc head ?




Mustangsaly

Novaboy-73
9th-April-2007, 02:46 PM
NastyZ28.com has some wonderful decoding pages ...

Small Block Heads Reference - http://www.nastyz28.com/sbchevy/sbch.html

1967-70 3970126 327 1.94 1.5 is the closest I found ...

are you sure it ends with 128??

126 head isn't a bad head .... typical stock GM 70's style 76cc head. I wouldn't toss'em : )

stock z/28
9th-April-2007, 02:53 PM
Hello,

All of the 126s I have seen (there may well be other applications) have come off of 69-70 regular fuel 350s. Both 2 and 4 barrel versions.

They are very comparable to the 441s but in my opinion they dont flow as well.

The the thing to me that stands out on these to me is the way the valve seats are machined. They appear to be "counter bored" and sunk a bit with sharp edges in the chamber and bowl.

I converted quite a few of these to 2.02 and 1.600 to correct this, and saved the 441 for "class" type engines.


Good Luck


Jeff

Mustangsaly
9th-April-2007, 03:58 PM
these are fresh with 1500mi on them. they were put on a 69 caprice 2dr with a fresh mild 383 build. he caprice was resto mod build (the heads have new comp springs and retainers and 2" stainless intakes and 1 1/2 stock exhaust valves and screw in studs. The intake ports are gasket matched and the chambers have been polished. ) the car and motor build was done in fall and the car was driven/broke in and then set the winter, and the next spring they put after market heads on the 383 to get more outa there 383 build and I bought the heads with only 1500mi on them. to me they looked like a fair set of 76cc heads with the bigger intake valves springs and such.

thanks

Mustangsaly

stock z/28
19th-April-2007, 11:25 AM
Hi,

Just curious did you ever figure out what your heads were?

slickman
19th-April-2007, 11:30 AM
I have a GM casting book at home, I'll check when I get home from work if you still need the info..

Fatcat
19th-April-2007, 01:49 PM
The 128 casting has a 161 cc intake runner as does the 441 casting. The 441 has a 65 cc exhaust runner, the 128 has a 62 cc exhaust.

Mustangsaly
19th-April-2007, 02:04 PM
Hi,

Just curious did you ever figure out what your heads were?

No I've been to busy to hit the storage and check the #s. maybe the end of the month I can check em out.


Mustangsaly

Dawg
19th-April-2007, 09:21 PM
3970126 comes up as a 1967-1970 327 head, 1.94/1.50 valves. That's all the info I have.