thin, crack prone, big chambers 76-80ish

 

The 993 casting is a heavy casted head that came on the following:
3998993....72-73...307/350......75cc chambers
3998993....current..350.........Goodwrench crate motors,"Hecho en Mexico", 75cc chambers
They aren`t that great for performance, being they have a large chamber and a not so good intake port. These are the basic smog heads.

 

was just wondering what anyone thinks about these heads 3998993 (68-76)

There not the best heads for sure, but depending upon your budget, you can actually get some surprising results. Some time ago Chevy High Performance magazine did a Mr Goodwrench 350 build up from stone stock to screaming wild in itty bitty steps see the included URLs.

http://www.chevyhiperformance.com/techarticles/46320/index.html



http://www.chevyhiperformance.com/techarticles/46326/index.html


Warning! Reading beyond this point brings out the Greed for Speed!



http://www.chevyhiperformance.com/techarticles/46359/index.html



http://www.chevyhiperformance.com/techarticles/46364/index.html



http://www.chevyhiperformance.com/techarticles/46370/index.html



http://www.chevyhiperformance.com/techarticles/46438/index.html



http://www.chevyhiperformance.com/techarticles/46461/index.html



http://www.chevyhiperformance.com/techarticles/46467/index.html


These are also reprinted in a larger book published by CHP titled;

"Small-Block Chevy Engine Buildups: How to Build Horsepower for Maximum Street and Racing Performance"

Another really good read for the budget builder is; "How to Build Max Performance Chevy Small Blocks on a Budget"
By David Vizard

Bogie

 

They are the best flowing of the large chamber heads along with 487s.........not that thats saying much.
If ya got um and there in good shape there OK for a mild motor.I got a set on my engine now.
As far as I researched though,I don't think they are crack prone like the 882s....but I may be wrong.