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4.2 258ci Cylinder Head Overhaul??

6K views 11 replies 6 participants last post by  JeepingShtHpns 
#1 ·
4.2 Cylinder Head Overhaul??
My 88' hasn't been messed with in a while and I don't feel like i can rely on him fully yet.
I want to overhaul or rebuild my cylinder head.

When i changed a head gasket about a year ago it was bad in there. But now I have time and some cash to do it and i wanna get it done. However I need some help, I know how to take it a part and put it back.

Is there kits? (I couldn't find any)

What parts do I need? (I know the basic stuff like valves, springs, push rods rocker arms...)

what are good/performance parts I should use?

Upgrades???

Tips/Advice?

Thanks for helping out a fellow jeeper :thumbsup:
 
#2 · (Edited)
4.2 Cylinder Head Overhaul??
My 88' hasn't been messed with in a while and I don't feel like i can rely on him fully yet.
I want to overhaul or rebuild my cylinder head.

When i changed a head gasket about a year ago it was bad in there. But now I have time and some cash to do it and i wanna get it done. However I need some help, I know how to take it a part and put it back.

Is there kits? (I couldn't find any)

What parts do I need? (I know the basic stuff like valves, springs, push rods rocker arms...)

what are good/performance parts I should use?

Upgrades???

Tips/Advice?

Thanks for helping out a fellow jeeper :thumbsup:
The first and best upgrade you can do is a 4.0l head. Then upgrade your cam. Just avoid the first few years of the 0331 cast # they are prone to cracking. You should be able to get one for $100 or less at a pick and pull. Next you could put in bigger valves I'm going with 1.94 stainless Chevy valves on the intake side and 1.50 on the exhaust side. Now with that done you may need to check on the length of your push rods to insure you get the right length. But if you don't go the bigger valves I would go the 4.0l head for sure. It is good for about 20 hp. The internet says 50hp:rolleyes: but I don't think it will be that much unless you get the fi with the head then maybe. This will help. http://offroad-review.com/new/index.php?page=68
 
#3 ·
To answer the OP's question more directly, you should have the head dipped and bead-blasted, first. Then have the machinist do a 3-angled valve job. Stainless steel exhaust valves are a relatively cheap upgrade that I'd consider. Roller rockers are another one. Of course, new pushrods and springs.

You can port-match the head to the gasket, which will gain you a few HP. And if you want to get anal, like I did, you can also Gyptal paint the inner surfaces to improve oil flow (see pics).

Good luck,

Matt
 

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#4 ·
First, have the head magna-fluxed for cracks.
If that checks out. THEN, go ahead with the rebuild.
Have it ported while your at it.
Do not go the cheap in parts. That costs you more in the long haul.
Unless you have a FULL machine shop, you are best to let a pro do this work.
LG
 
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