how can i make power with a 4.2 - Page 2

TerryMason · #21 (**permalink**) 09-04-2007, 10:16 AM

have you upgraded the ignition yet?

http://www.jeepz.com/forum/showthread.php?t=16904 (TFI ignition upgrade)

It made a huge improvement in my 85 cj7, and was really cheap.

chaos.258 · #22 (**permalink**) 02-20-2008, 11:20 AM

To Mike B, This is what I did to my 4.2. Remove stock carb. intake and exhaust manifolds. Replace with 390cfm Holley carb. Model 4160 P/N 0-8007. Replace intake manifold with Offenhauser alum. intake P/N 6257-DP. Replace exhaust manifold with Pasesetter 6-2-1 header P/N 70-1128. This will solve some of your vacuum problems, give you more horsepower and better m.p.g. Parts for this project were about $900.00. The next phase of this project is going to be an ignition and coil upgrade probably M.S.D. These are a few things you might want to consider before you spend the big bucks on a new aluminum head. What the hell, swap the head too. Long live the 4.2.

RBLUE · #23 (**permalink**) 03-13-2008, 06:05 PM

GEAR'S/tera-low 4.3-1

WV77CJ5 · #24 (**permalink**) 04-21-2008, 07:48 PM

So is the Weber 32/36 no good for a '77 CJ5 4.2L?? I am trying to upgrade mine and can't decide which carb to purchase and get a good value.

franked · #25 (**permalink**) 07-02-2008, 10:49 AM

OK this is a good time to ask, I have a 78 Cj7, will that efi conversion work for me?, bay area CA, same smog checks you got in So-Cal. And is there a header avail for these jeeps, 258 I6?