1revnrex

Got a set of irons at the yard from an unknown year 12A, what are some defining characteristics between years? Also there is some rust on the faces of them, is this going to be an issue in using them or can I just get them resurfaced? I'll try to get some pics up later on of them, Im plannin to bridge them or just use'em to practice on if they are junked.

j9fd3s

there arent much differences between the years.



74-75, black painted, big ports

76-78, black painted, smaller ports

79-80, nitrided

81-82, has an oil pressure tap on the rear iron, they have a heater hose nipple, not the screw in hose thingee

83-85, has a T heater hose for the beehive oil cooler

1revnrex

Pretty sure its an 83-85, I seem to remember when I hid these parts last year it was out of an 83 GSL. Plus it has the T fitting. What about the rust?

j9fd3s

if its not too bad, you can sand it by hand with some wd40, or similar. if its still pitted they can be surfaced, if its pitted after that its junk

1revnrex

Im gonna try wetsanding with some machine oil and 1000 grit wet/dry and see what comes of it. Do you know if Ito ever had 4 port 12A templates?

ArmyOfOne

I'm not sure if he had 12A templates but you can do some pretty aggressive porting on a 12A. So the aggressive streetport templates theoretically could be used.

Jeff20B

j9fd3s, I have an oddball rear iron. It's a nitrided Y casting with the oil pressure hole, and the heater fitting is pressed in but the same length as a GSL-SE. I'm thinking it's J-spec.

j9fd3s

could be they had the 4 port 13b after 78 in japan. could also be an 81-82 12a

1revnrex

These irons are pretty pitted come to find out, whats the max I can take off of these things without going over the service limit? Also do you think a normal machine shop would be able to do these, I cant see it being too much more difficult than decking a 4 cylinder block?





-Shawn