258 Upgrades?

[classicfins]

Hey everyone...
New to the site and I'm bleary eyed already from reading all the awesome info available here. It's great! I am also new to jeeping. And 4x4's in general. I've never owned any 4x4 before, except for ATV's, so I am really having a time getting used to all the different setups, upgrades, and terminology.

Anyway, I just picked up a '79 CJ5 with the AMC 258 i6 / 4.2l 6cyl and 3 speed tranny. It's a project, it's rough, but it was cheap, which fits my budget right now thanks to being laid off at the moment. It needs lots of rewiring, paint and bodywork, new steering column, exhaust... You name it, it probably needs it. lol

I am curious about any possible upgrades I can do to the AMC 258 i6 / 4.2l to help with the power, performance, etc. I looked through the forums but didn't see much on upgrading this motor. Do any of the later models have interchangable heads, manifolds, fuel injection that could be swapped in for better performance? Any info would be great. Thanks!

 

[poppatello]

Hmm, got laid off so bought a rough/cheap jeep. That takes balls or well other words. Welcome to our great home. There is never a good time to get into this great hobby so now you just have more time to work on it. There should be quite a bit of info on this forum about upgrading the AMC 258 i6 / 4.2l . You can do a lot of cool stuff to that motor.

Some will tell you to just swap in a V8 and be done with it. It all really depends on what you want to do with the jeep. Personally if I didn't have the AMC 150 in my jeep now I would keep the AMC 258 i6 / 4.2l if it came with one.

Look in the search engine on this forum and type in AMC 258 i6 / 4.2l . You will see a nice long list of threads that has AMC 258 i6 / 4.2l in it. Just scroll down until you find a topic that looks like yours. Also check out other internet sites and Youtube is a very popular place for info, sounds, pictures of info stuff on all things jeep

Some of the things you can do is stroke your AMC 258 i6 / 4.2l to a 4.6 with bigger heads and stuff. You can do a head swap from a 4.0 for better power and little better fuel economy. You can swap out your intake for a 4.0 intake and so fourth. Your pocket is your limit.

A few things that is a must on this forum. Pictures. Whenever you do something you must post pictures.

Again welcome...

 

[poppatello]

Oh and GET RID OF THAT POS CARB.


Is that a fiberglass body???

 

[Jimbos76cj]

First 2 upgrades for the AMC 258 i6 / 4.2l is ignition and carb change.

Either upgrade to a HEI or do the team rush upgrade. I prefer HEI for simplicity but a lot of folks here love the team rush.

Next is to upgrade the carb to a better one. Not quite sure what carb you have now but it looks to be a small one barrel. You might have to change your intake over to a newer model AMC 258 i6 / 4.2l and get a 2100 to go with it.

Other the. That look for vaccum leaks, bad grounds, and give it an over all tune up. Check the timing and replace the fuel filter as well. Good luck.

 

[classicfins]

Oh and GET RID OF THAT POS CARB.


Is that a fiberglass body???

Thanks poppatello! No, it's a steelie..

 

[classicfins]

First 2 upgrades for the AMC 258 i6 / 4.2l is ignition and carb change.

Either upgrade to a HEI or do the team rush upgrade. I prefer HEI for simplicity but a lot of folks here love the team rush.

Next is to upgrade the carb to a better one. Not quite sure what carb you have now but it looks to be a small one barrel. You might have to change your intake over to a newer model AMC 258 i6 / 4.2l and get a 2100 to go with it.

Other the. That look for vaccum leaks, bad grounds, and give it an over all tune up. Check the timing and replace the fuel filter as well. Good luck.

The carb is a 2bbl It's in bad shape though and needs a kit, or swapping out. WHat did the 2100's come on?

 

[rr41mag]

Iput a dual collector header on mine. Upgraded to an HEI distributor. Rebuilt the carb and built my own cold air intake. I like the torque of the six.

 

[Jimbos76cj]

You can find them mostly on amc v-8's I've seen go from free to $100. You need a $45 dollar adapter plate from a guy on eBay and your on your way. Mr.gasket and transdapt make a cheaper version of the adapter but I've had nothing but horrible luck with em. The eBay guy makes his out of solid steel so they don't warp, crack or leak. The same guy will sell a complete kit, the carb, adapter, HEI and relays for a decent price.

 

[thiswontbetooexpensive]

Welcome from Texas. My Dad was born and raised in Ruston. Glad to have you here and nice CJ!

 

[johnnyreb]

I agree on both upgrades. Done most of the team rush and prepping a MC 2150 for install.

 

[classicfins]

Thanks Guys!!!

 

[hole]

I understand your un-employed, but if you can get your hands on a FI setup you wont be disappointed

 

[IOPort51]

I was talking to an engine builder at the car show I went to a couple of weeks ago. He was building and selling the 4.6 AMC stroker engine.

I asked him where the power peaked on this engine and he proudly told me "about 5000 RPMs". He could not tell me what kind of horses he was making at 2-3000. I guess if I was running in waist deep mud a lot, maybe. Are there such things as 6.00:1 differentials??

 

[johnnyreb]

Just installed my MC 2150 today and even without tuning it (1 1/2 turns) and it purrs. I recommend hunting the junk yards for one.

 

[CJB4POWERBILL]

Motorcraft 2100 fo show ...I'm a newbie with same jeep as yours and read my profile for a few off the bat upgrades I did in last two weeks. Be glad to elaborate if needed.

 

[CJB4POWERBILL]

1983 CJ7 AMC 258 i6 / 4.2l T-5 . Got it home and no oil pressure period lol. Dropped oil pan and put new oil pump and main bearingsand rear main seal. Then I noticed the spark plugs looked likea big clob of charcoal. So then I did the distributor nutter and new motorcraft 2100 to take my fuel system and ignition out of the computers hand. New battery & terminals,New sunpro RPM gauge, New plugs, new wires, new dist cap & button then i set timing to 8* BTDC with dist advance plugged and idleat750 RPM. After setting the M/C 2100 idle mixture...finallyithumslikea

sewing machine .Then sprung a coolant leak in the passenger floor

board , so I did the upgraded chevy 103 blower motor and a new heater core to fix thatproblem (dontforget to order u a new defrost heater duct if doing the blower motor deal, cause old one is brittle and crumbles and add extra ground wire to blower motor mount BEFORE you bolt it back up to firewall).Now to deal with the valve cover oil leak, exhaust manifold leak, oil leak at oil dipstick tube, oil leak at distributor base, fuel gaugenot working, temp gauge not working, reverse lights not working, no dash illumination lightsatall, thatsallivefound

 

[Rollie]

One thing to do is find the number cast in the side of the engine. Decode that number and make sure you have a AMC 258 i6 / 4.2l . When I bought mine the guy who was selling it told me that it was a AMC 258 i6 / 4.2l . It is not. I brought it home and checked it out. I have a AMC 232 i6 . They look the same, so the only way to tell is to check the number on the block.

 

[1986cj7]

One thing to do is find the number cast in the side of the engine. Decode that number and make sure you have a AMC 258 i6 / 4.2l . When I bought mine the guy who was selling it told me that it was a AMC 258 i6 / 4.2l . It is not. I brought it home and checked it out. I have a AMC 232 i6 . They look the same, so the only way to tell is to check the number on the block.

I'm not 100% sure but I think I read some where that the 4.0L head will work on the AMC 232 i6 also. Maybe some one who knows for sure can chime in.

 

[CJB4POWERBILL]

Why u replacing head ? Not gonna get a power house out of the I6 anyway possible no matter Wat u bolt on. Not in my opinion. Either spend tha dough and go SBC for power or get your AMC 258 i6 / 4.2l in top shape with a few modern age upgrades...me personally went with getting AMC 258 i6 / 4.2l back to 100%. If u want a hot rod buy a Mustang or Camaro. But the I6 will serve you well if u spend some time on it.