jensennlj

I just pulled the heads off of an early model SBC 350. It's been rebuilt as a 383 stroker but I do not know the exact engine specs. Here are the numbers from the heads if anyone could help me ID what they are and how good they are basically. These are all off the driver's side(left?).

GM27 - 9998993
F83 - this was also stamped into the head.

The pistons have a "30" stamped onto them and they also have 4 symmetrical crescent concave pockets dug into them as well. Any help with that would be appreciated also.

Guest

Your 993 heads are nothing decent. 76 cc. About like 882s or maybe 487s.
When you get funds for better heads, verify the stroke, then ask us about what new heads to order.

jensennlj

THanks for the reply! I'm assuming they are cast iron because they have a specs of rust on them. I appreciate the insight.

jensennlj

I have a 3.75" stroke with those 76cc heads puts me at 10.3:1 compression. I've read that strokers take advantage of a higher compression, so should bigger CC heads be the best route? Or perhaps I should go with something with just increased Intake Runners. Any idea what the intake runner size is on my existing heads? They are 9998993's

sofakingdom

iTrader: (1)

No, you're most likely not at ANYWHERE NEAR 10.3:1 CR. Not sure where you might have come up with that?

4.030" bore, 3.75" stroke, .039" gasket (FelPro blue or similar), the stock .025" of deck clearance plus the usual "rebuilder" .020" for a total of .045" of deck clearance, 6cc valve reliefs, 76cc chambers:

Somewhere between 8.8 and 8.9:1.

The eyebrow shaped indents in the pistons are valve reliefs.

Intake runner size is typical of the crappy smogger heads; something in the 160-odd cc range.

The combination of that, the ginormous exh valve guides obstructing that port, and the huge poor-design smogger chambers, make that one of the castings most to be avoided. Basically they are head-shaped doorstops.

Yes, better heads would DEFINITELY be in order, no matter what your next performance goals are. THe best choice would depend on goals, budget, and the rest of the CAR, including what else is in the motor. (cam especially) As far as the CAR, the gears, transmission, and converter.

jensennlj

Thanks for the insight sofa. What are some good heads for an early model SBC stroker if i want about 400-425hp? There doesnt seem to be a comprehensive place that gives ratios of power -to- size on chambers or intake runners. I am already going to get the Performer RPM high-rise intake with a Holley 770cfm carb. What size heads should I get that cap me at about 400hp without sacrificing too much low-end torque? I've got about $600-800 to spend on heads.

BTW the rest of the car will be a stoutly rebuilt 700r4 and a 9-bolt rear end with 4.11 gears.

sofakingdom

iTrader: (1)

For that little money, aftermarket heads are basically out of the question, unless you can cone across a brother-in-law deal on some used ones. About all you can get for that is the cheeeeeeeeep Chinese castings that are unpredictable as to whether they'll even bolt up, let alone how they'll work; that youll then have to spend about an equal amount fixing the sloppy finish work they come with.

A good way to go might be the Scoggin-Dickey Vortec package. http://sdparts.com/details/scoggin-d...ter/sd8060arpm

Guest

While it is true that most "rebuilder" pistond are 0.020" short, this does not apply to any 383 pistons.
And assuming the heads are at 75 cc after the resurfacing part of a freshening, the compression should be about 9.2:1-9.3:1, which is good with those heads.
Also, larger cc heads will reduce compression. Smaller cc, like 64 cc, will increase compression.

Guest

Any decent heads are going to run $900 / pair, assembled. I suggest you check Edelbrock E-street heads, #5073, which would put you just under 10.5:1 with FelPro 1094 head gaskets, there's another $40. Match with at least a Comp XR276HR10, top with an Edelbrock Performer RPM AirGap, ( worth some HP over the RPM non-gap ) that should meet your goals for both HP and driveability.