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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: project85 on November 08, 2010, 05:30:31 am

Title: Engine and Head Questions????
Post by: project85 on November 08, 2010, 05:30:31 am: i have a 350 engine a guy gave me a few years ago. he said it was a target motor unsure of the year he bought it. i pulled the casting number off of the block (10066036) and googled it. it came to a goodwrench motor that as sold it made 290hp 325ft-lbs on the dyno. it listed the head and cam cast/part numbers, and the carb and intake that was used during dyno. it called for a holley 600cfm and an edelbrock performer intake. the engine has a holley 600cfm and a performer intake. the casting number on the heads do not match the goodwrench info. the casting number on the heads is 3998993. which i googled and got a few different answers. 1 site said they are 64cc heads and another said they are 1.94/1.50 76cc heads. goodwrench on the dyno called for 1.94/1.50 76 cc heads. i'm assuming that this is the engine that came from target. i cannot get ahold of the guy who gave me the engine to ask if he switched heads.

my question is are these heads any good or should i rework them or just search for another set to put on the engine? my goal for my engine is 350hp and 400ft-lbs. this motor seems like a much better starting poin then the 76 vette motor that is in my truck now (190hp?????).

i'm gonna start pulling this motor apart and check numbers as i go. it sat covered outside for a few years and i've had it in my garage for 4 years so i imagine all the gaskets need to be replaced at the very least. any help with the heads would be awsome.

thanks
Title: Re: Engine and Head Questions????
Post by: Captkaos on November 08, 2010, 07:21:15 pm: 1968-76 3998993 350 1.72 1.5 - truck
They are small valve heads. If you rebuild them you will need to have them opened up for bigger valves. Be cheaper to buy better heads.
Title: Re: Engine and Head Questions????
Post by: project85 on November 08, 2010, 08:31:21 pm: i have seen both online. i've seen it as 1.72 64cc heads and 1.94 76cc heads

http://www.chevellestuff.com/qd/head_casting_by_year.htm

http://www.dragtimes.com/parts/SBC-CYLINDER-HEADS-GM-CHEVY-3998993-350-400-CAMARO-993s_150481493146.html

http://www.novas.net/forums/archive/index.php/t-1731.html

i'm still confused. it seems these heads are heavy casted and ok as is and have potential maybe? but it seems they are 1.94-1.50 but i'm still not sold on it. if i pull the heads off i'm gonna have to check the port sizes. any help with this would be great. thanks
Title: Re: Engine and Head Questions????
Post by: reallyrusty on November 09, 2010, 07:48:54 pm: If this motor has sat for six years, you might want to consider tearing it down to the block and start fresh.
Six years is a long time for a motor to sit. You could have anything from rust pits to stuck rings, especially if some of that time was outside.
just an opinion.
Title: Re: Engine and Head Questions????
Post by: ohio hab on November 09, 2010, 08:02:36 pm: According to my old Chevy cylinder book, they are 76cc, 1.94/1.5 inch valves for the" Hencho en Mexico" G.M. Target/Master/Goodwrench crate motor. These heads really have no performance value. There are much more better choices out there for an SBC.
Title: Re: Engine and Head Questions????
Post by: project85 on November 10, 2010, 05:54:28 am: my plan is to tear it down and clean the block up and possible bore it out, not sure yet where i'm gonna go. i've just been trying to see if these heads are worth reworking or just but a new set. it seems like i should look a buying a new set once i figure what kinda power i want to make with the motor.

thanks