What head do i use ?!?!?

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05-08-2014, 08:41 PM

88comanche

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Model: Cherokee

What head do i use ?!?!?

The rebuilt 4.0 motor I put in my 1988 Comanche at the beginning of the year is showing the signs of a cracked head...the mysterious missing coolant & milky looking crap in pockets of oil filler cap, also found scrapped up on end of dipstick (figure this is collecting in dipstick tube) and in the large vent tube going to air filter; dipstick also showing rust near handle...looked at small area of head through filler cap and didn't see any kind of build-up of milky crap or green tint that can be left by antifreeze leaking into head area...the oil looks fine, recently changed and still has clear honey look. I suspect that the higher Phoenix AZ temps that are setting in and associated increase in engine temp is causing whatever micro-crack that is there to open up as I didn’t start having the problem until the last few weeks.

I've read several posts on cracked heads (mine's not a 0331) and several stressed buying 'new' casting replacement heads from several sources, heads touted to have thicker casting in weak areas, or an AMC JEEP CHRYSLER 258 4.0 H.O CONVERSION CYLINDER HEAD...also read that the “0630” head has smaller ports and the “7120” is apparently an option but not sure what advantages/disadvantages it has. Needless to say all this left me unsure of what would be my best choice and what I should avoid...I need to buy the replacement ASAP, what would you do for a replacement head? Stock replacement OK though the rebuilt engine has mild cam & slightly higher compression so something that might enhance performance would work.