Re: [Amc-list] 4.0 #7120 Head to 258 Swap

[Wrambler242@xxxxxxxxxxx]

Cause even if you don't do the bore taper the 4.0L head is a better choice!
The taper the bore theory is not new, but realy not been addressed far enough to be sure it helps and ping issues.
4.2L heads before 87 when they got the aluminum cover are pretty crappy for several reasons, ports, valve sizing, leaking plastic or tin covers. In 87 they got a good cover, but the ports still fall behind the 4.0L models of any year.
  You can spend the money on valves, porting, etc or just plug the water holes in the 4.0L head, touchup the valve job and go.

--
Mark Price
Morgantown, WV
1969 AMC Rambler, 4.0L, EFI, T-5
2004 Grand Cherokee Laredo, 4.7L, Quadratrc II
" Chronic Pain Hurts"

 -------------- Original message ----------------------
From: Tom Jennings <tomj@xxxxxxx>
> Greg Taylor wrote:
> > Hey guys,
> > Sounds like the 4.0L head swap takes some work.  Why not just use an existing 
> high-compression 258 head and do the Chevy 1.94/1.50 valve swap?  Cost with all 
> chevy parts is 
> reasonable and the performance difference is AMAZING. FWIW, on my stock 
> bore 258, we cut the exhaust down to a 1.45" to be safe on clearance 
> (without mocking anything up).
> 
> 
> For me, and many I assume, it's the "comes with efi factory made it it 
> all plugs together parts at NAPA"!
> 
> Good head, plus EFI.
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