I have a friend that has a 4.0 Jeep head that was traded to him for some nice wheels...now it is compleatly rebuilt. I may buy it from him for a very good price but what I want to ask you experts is the casting is...# 2688 Now how good of a head is it I have a 98 Xj...will this head be better or worse than what I have now ..thanx guys
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Question on head..
- Thread starter FIRE CAT
- Start date
5-90
NAXJA Forum User
- Location
- Hammerspace
I don't recall a #2688 head - there was, however, a #2686 head.
#2686 - 1987-1990 AMC 242ci inline six (A/K/A "RENIX.") First-generation cylinder head for AMC242, noted for having the inlet and exhuast ports on a common line (they were raised ~5/8" later to improve intake breathing and airflow.)
All AMC242 cylinder heads will interchange with all blocks, but there is a dividing line at 1990/1991 for the intake manifold (due to ports being raised, as I'd just mentioned.) Any AMC242 cylinder head will also fit on a later "Wide Deck" AMC258 engine block (1975 and later, I think,) which will both improve compression and breathing. Make sure you have casting #2685 on your 258 before you try this.
Special screws or bushings may be required - the AMC258 used 7/16" cylinder head screws, while the AMC242 uses 1/2" screws.
Is there anything else you'd like to know?
#2686 - 1987-1990 AMC 242ci inline six (A/K/A "RENIX.") First-generation cylinder head for AMC242, noted for having the inlet and exhuast ports on a common line (they were raised ~5/8" later to improve intake breathing and airflow.)
All AMC242 cylinder heads will interchange with all blocks, but there is a dividing line at 1990/1991 for the intake manifold (due to ports being raised, as I'd just mentioned.) Any AMC242 cylinder head will also fit on a later "Wide Deck" AMC258 engine block (1975 and later, I think,) which will both improve compression and breathing. Make sure you have casting #2685 on your 258 before you try this.
Special screws or bushings may be required - the AMC258 used 7/16" cylinder head screws, while the AMC242 uses 1/2" screws.
Is there anything else you'd like to know?
5-90
NAXJA Forum User
- Location
- Hammerspace
dss said:
I take it you're no longer wondering why I'm writing my books?
goodburbon
NAXJA Forum User
- Location
- Westcliffe Colorado.
Here's the short of it: the manifolds you have aren't quite compatible with the head, but the engine block is.
5-90
NAXJA Forum User
- Location
- Hammerspace
FIRE CAT said:
It will not. The #2686 head does not breathe as well as the later heads, and you'd have to swap intakes and adapt the throttle body to the RENIX intake anyhow.
Stick with the #0630 head - it won't be worth the trouble to swap.