well today i went out and pulled the valve cover to fix a rocker tapping, well i found the cylnder its tapping and tighten them down, they never catch just keep tightning, so i then decide that i now need to take them off to get screw in studs, damit.

well i go to run the casting numbers to see what kidn of heads they are to see if they are worth being worked over since i have 3 other pairs of heads. i copy this number donw

899883
J2472
GM
6

what do you all make of this, by the way this is the passenger side head and did i copy it down right or what.

please help me. thanks

 

Squeeks,

"899883" doesn't show up at www.mortec.com Check the casting number carefully and with a good light. An '8' can look like a '3', and vice versa.

If you determine the heads are not worth a lot of work, you have the option of driving the stud back down and cross-drilling/pinning the stud, of removing the stud and tapping for a screwed repair stud. Screwed studs are about a dollar apiece. Roll pins are dirt cheap, but will require a long (aircraft) drill and either a TiN coated or carbide drill to penetrate the hardedned stud. Depending on the locations, you might not even be able to get a drill (even an angle drill) into the space necessary to drill the stud boss. Personally, the tapping method is my preference.

If you tap for a screwed stud and decide to work the heads over, you can use the same threads for good replacement studs after boss machining.

 

I second that. I checked Mortec too, and couldn't find an exact match.

The "Hecho En Mexico" crate motor heads have a similar casting #, tho.

As Vader says, recheck that #.

 

ya i used Mortach also, but i guess when it stops pouring down rain ill go recheck it.

 

3998993 is the "Hecho en Mexico" casting.... probably what it is

 

ya its the

3998993 = 45cc chamber
Hecho En Mexico

are these haeds any good, meaning should i take them off, have them machined, ported more and have them polished, AND have screw in studs??

 

What are you running them on 350? The 993 aren't just Made in Mexico crate heads, they came on production vehicles also. I have a set off a 73 3/4 ton truck 4-bolt 350.

 

Oh yeah the 993's that came on production vehicles are decent smog heads. They flow amongst the best smog heads, the only problem is they have 74cc chambers.

 

so would it be worth it to take these in and build them up with aftermarket springs, screw in studs, port them more and this time polish them.

Mortec said"
3998993....72-73...307/350......75cc chambers"