Head ID

[sedaliatim]

Hi guys,hey I've got a set of 2.9 heads on my workbench with the rectangular not the oval rocker pads like the pics in the tech library but there was an 86TM along with a 6090CAB casting number next to the middle spark plug hole.It also has an 89 cast near the middle rocker pads and C8S1A cast near one of the end intake ports and the 8mm instead of 10mm ground bolt on the end of the head like someone said .My bronco was born in February 1989 but I didn't think the new heads came out until late 1989 with an 89TM casting number,do I have a transition era heads or something, just curious.

 

[Psychopete]

See here:
http://therangerstation.com/forums/showpost.php?p=32490&postcount=3

Pete

 

[sedaliatim]

Hi Pete. I was referring to what Allan said about the 10 mm grounding bolt on the end of the head but according to the tech library as far as resistance to cracking is concerned, the improved "thicker" heads have rectangular rocker pedestals which mine have but mine also have the older 86 TM casting mark instead of 89TM.My question is do I have the improved "thicker" casting. I haven't found any cracks but I don't want to put the older "crack prone" heads on top of my shiny new motor. Thanks

 

[kunar]

it sounds like youve got the good ones. i dont think there ever were any 'transition period' heads. they are either the good ones or they are the the junk ones. check this link out. and fwiw, i had an 87 with the new heads and new valve covers. im pretty sure it didnt come this way from factory, but its common practice to swap out failure prone parts with their more reliable replacement

 

[sedaliatim]

Yea,I was looking at that in the tech library, the picture of the newer "thicker" heads show rectangular rocker pedestals and the "straighter" valve cover mating surface like mine have, not the oval ones of the old style heads but my heads have the older 86 TM casting mark,not 89 TM like the newer heads, And like AllanD said in a previous post the newer heads have a 10mm instead of 8mm ground lug hole on the end of the head.I don't mean to be a pain in the rear,but I'm still wondering if I have the newer style heads or not because of the casting mark.Maybe it was early Monday morning at the foundry.