mods to play with the 258.. thinking cam & boost! -
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post #1 of 4 Old 05-08-2013, 10:21 AM Thread Starter
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1963 FSJ Gladiator 
Join Date: May 2013
Location: panama city
Posts: 12
mods to play with the 258.. thinking cam & boost!

so Im playing around with this carbureted wonderful new toy I got that is my '63 gladiator. I'm likely picking up a 360 today or this weekend and may also have a line on a 400 SBC package.. in the meantime the I6 seems to run fine but just has no balls and I'm playing around trying to learn about carbureted engines (I'm a turbo/EFI kinda guy)

so while I'm trying to decide what V8 and running gear to go with I thought I might play around with the I6 that's in here and see how it goes.. I can easily fab up a flange and drop in a used junkyard turbo and use one of hte intercoolers I have lying around and boost her up a bit but am also considering a moderate cam but know nothing about these engines.. what do you guys think? new carb/ manifold? new cam? F'it all and just boost it? ;p looking for real input here and appreciate anything you guys have to offer. I know I seem really ignorant.. because I am but that's why Im doing this is to get caught up on the old school stuff every gearhead should know since I got a late start and only know how to play with the computerized stuff..

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post #2 of 4 Old 05-08-2013, 11:35 PM
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1982 FSJ Cherokee 
Join Date: Jan 2012
Posts: 865
The 258 is one of the best engines out there, ALL i6 engines lasted

if only gas was cheaper
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post #3 of 4 Old 05-12-2013, 11:16 AM
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1998 ZJ 
Join Date: Sep 2007
Location: Cannon AFB
Posts: 160
Downfall of the I-6 is head flow. They respond well to it! If you are doing that then you should also find a 2 brl carb from an AMC v8 and adapt it to the 6. You can get the adapter from a local parts store.

1978 J10 Honcho Truggy project 401/Tons/???
1983 J10 Honcho Stepside I-6 add a leaf/33"s
1988 Grand Wagoneer 401 4"/34"s
1998 ZJ 5.9 Limited 4.5" LA/33"s
1999 WJ 4.0 Limited
2003 Ram 1500 w/built 12v cummins
2004 Ram 2500 Cummins tow rig
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post #4 of 4 Old 05-17-2013, 10:06 AM
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1983 FSJ Cherokee 
Join Date: Feb 2007
Location: Pensacola, Fl
Posts: 529
Humm, turbo....I am thinking along those lines with my 4.6 Stroker build located here

I have not had a turbo on the 258 I had when I had one but I did put in a HEI dizzy I picked up from a junk yard Chevy pickup. I also put on the 4.0 head (flows better and you need to either epoxi or weld some water ports to mate it to the 258 block) Modified the 258 intake to fit on the 4.0 head, and put on a 2100 2 bbl carb with the correct jets. She was a good running engine.
Now I am going Stroker and seeing how that will be in a FSJ.s

If you want to go for MPFI on the 4.0, check out thread;

For the turbo on the 4.6 I am thinnking about routing my exhaust up the dizzy side of the engine then put the turbo on. That way there is no need to make a new exhaust manifold and I can run the exahust back down the same way. I only want about 6-8 lbs of boost so we'll see how that goes.

Good luck and I will be watching as I also want to find a "junk yard" turbo set up that might work for these engines.
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