I found a set of these heads while cleaning my garage. They have 1.94 intake, and I assume 1.5 exhaust. (did not measure exhaust......) Screw in studs, and guide plates. They are a perimiter bolt style head, and I don't really have much use for them, as I want my motor to "appear" stock.

Anyone know anything about these? The best I could come up with they are heads from an early 70's small block chevy. (yep, real informative.........)

 

They are considered crap, but will work fine if ported on mild strokers or 400 sbc's. They are not the best and considered "smog garbage" but they aren't that bad, they are the best of the worst. 993's have large 72-74cc chambers, but they have heavy casting that can, take a good porting job.

Mildly Ported 993's with stock valves.

1.94" In
.05-.50"
31.000000
60.099998
93.300003
125.099998
155.000000
180.000000
200.100006
213.399994
220.500000
224.100006

1.60" Ex
.05-.50"
24.000000
50.099998
75.000000
94.599998
110.300003
122.099998
140.000000
155.100006
167.199997
175.000000

 

Thank you. That is as I expected.

 

Just as a side note you can also open these up to 2.02/1.60 and stay around .500/.500 on the cam and have them work on a 305

 

They have big 76cc chambers. You'd really tank the compression on a 305 with these heads unless you used some domed pistons.

In stock configuration these heads are not really anything special. They are the heads supplied on the GM "Targetmaster" universal replacement 350 engine (250HP rating).

 

Or you are supercharged

 

993's are a little less then 76cc's as much as 75cc's.