4.2 258ci Cylinder Head Overhaul?? - JeepForum.com
 
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post #1 of 12 Old 09-30-2013, 11:37 PM Thread Starter
JeepingShtHpns
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4.2 258ci Cylinder Head Overhaul??

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

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post #2 of 12 Old 10-01-2013, 05:37 AM
my1986cj7
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Quote:
Originally Posted by JeepingShtHpns View Post
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
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 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

Last edited by my1986cj7; 10-01-2013 at 05:47 AM.
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post #3 of 12 Old 10-01-2013, 05:58 AM
Matt1981CJ7
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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
Attached Thumbnails
Glyptal1.jpg   Glyptal6.jpg  
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post #4 of 12 Old 10-01-2013, 09:19 AM
LumpyGrits
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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

Have'n you along, is like loose'n 2 good men
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post #5 of 12 Old 10-01-2013, 11:37 AM
bligon64
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Does the Glyptal paint just sort of smooth out the surface to reduce drag? Im in the middle of my 4.0 head conversion and since i have it open i figure ill do everything i can.
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post #6 of 12 Old 10-01-2013, 11:37 AM
Prspallone
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Check my build tonight and I will be posting pictures of everything your head should need done to it.
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post #7 of 12 Old 10-01-2013, 11:42 AM
Matt1981CJ7
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Quote:
Originally Posted by bligon64 View Post
Does the Glyptal paint just sort of smooth out the surface to reduce drag? Im in the middle of my 4.0 head conversion and since i have it open i figure ill do everything i can.
Yes, it smoothes out the casting imperfections and allows the oil to drain back to the pan faster.

It's probably overkill for a Jeep engine, but I figured every little bit helps.

Matt
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post #8 of 12 Old 10-01-2013, 05:27 PM Thread Starter
JeepingShtHpns
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Quote:
Originally Posted by my1986cj7 View Post
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 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
So if I get bigger valves i cant use the standard push rods? and How do I find out the right length?
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post #9 of 12 Old 10-01-2013, 05:59 PM
bligon64
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You should be able to go to an auto parts store and tell them you need push rods for a 4.0 head
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post #10 of 12 Old 10-01-2013, 11:06 PM
Prspallone
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If you get your head overhauled they should be more or less something like this

1626785/index3.htmlhttp://www.jeepforum.com/forum/f8/ol...85/index3.html
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post #11 of 12 Old 10-01-2013, 11:26 PM
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Quote:
Originally Posted by JeepingShtHpns View Post
So if I get bigger valves i cant use the standard push rods? and How do I find out the right length?
Pushrods really should be measured and ordered after the head is assembled and mated to the block. There are several variables that can influence the correct length.

Comp Cams sells an adjustable pushrod measuring tool.

Matt
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post #12 of 12 Old 10-06-2013, 12:36 PM Thread Starter
JeepingShtHpns
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Quote:
Originally Posted by Prspallone View Post
If you get your head overhauled they should be more or less something like this

1626785/index3.htmlhttp://www.jeepforum.com/forum/f8/ol...85/index3.html
I checked it out thanks Man that is going to help a lot when i do it.. And thank to everyone else for all the advise and word of advice ill be back if i need anymore help when i start it.
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