Engine New to me CJ7 and old school CJ 5 set-up

[PRM]

Hi, I just got an 86 CJ7 , with a bone stock AMC 258 i6 / 4.2l (50k miles), including all EPA pollution equipment. Back in the day I had an 80 CJ5 , with the AMC 258 i6 / 4.2l , but this one had the Offenhauser Dual plane intake, a Holley 390 (4bbl), and headers with 'Hush Thrush' mufflers. Seems like the old set- up had more usable torque and was more zippy on the road than the stock set up I have now. So, my question is, is the old school set up I had in the 80's still the way to go, or is an EFI set up such as the Holley Stinger a better option. I'm guessing that regardless of the intake system, headers are still the best exhaust option.
-Paul

 

[Manic Mechanic]

i run headman 6-1 headers gm hei ignition and mc2100 carb. perfect set up and only vacuum i have is timing advance on dis brake booster and pcv valve. of course in MD i can get away with no emissions

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[PRM]

i run headman 6-1 headers gm hei ignition and mc2100 carb. perfect set up and only vacuum i have is timing advance on dis brake booster and pcv valve. of course in MD i can get away with no emissions

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Are you using a stock intake manifold?

 

[hole]

You have more than a few ways to go. Throttle body EFI's or Mopar MPI (what I'm running) or stick with carbs and various different set-ups with those. What is your end goal with it? Off-road much? Planned tire size? Emissions testing where you live?
And welcome

 

[Manic Mechanic]

Are you using a stock intake manifold?

yes stock manifold. i run an adapter plate to go from stock to the square bore of the 2100

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[j6824]

Sniper's hard to beat, regardless of intended use

The general opinion on headers for the AMC 258 i6 / 4.2l (from a low speed/idle perspective as it pertains to wheeling) is one of diminishing return...specifically, performance gain vs. heat production

Like Hole said, how you intend to use it will likely be the governing factor

 

[PRM]

Thanks to all for the prompt replies. This jeep will see very little off road use. An occasional fire trail or dirt road. It's mostly a nostalgia thing for me, having had one in the 80's.
33 Goodrich tires, with a 2 " chassis lift. No emissions here in MD.
My goal is better acceleration thru the gears ( on the street), a little more low-end grunt, and if I'm being honest, a nice throaty exhaust note, without being obnoxiously loud. Basically the same attributes that my 80 CJ5 had back in the day.

 

[Manic Mechanic]

Thanks to all for the prompt replies. This jeep will see very little off road use. An occasional fire trail or dirt road. It's mostly a nostalgia thing for me, having had one in the 80's.
33 Goodrich tires, with a 2 " chassis lift. No emissions here in MD.
My goal is better acceleration thru the gears ( on the street), a little more low-end grunt, and if I'm being honest, a nice throaty exhaust note, without being obnoxiously loud. Basically the same attributes that my 80 CJ5 had back in the day.

pm sent


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[PRM]

yes stock manifold. i run an adapter plate to go from stock to the square bore of the 2100

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Manic, I'm assuming you prefer the 6-1 headers because of a better engine tune, or is it just a simpler installation? I ask because I kinda like the look of dual exhaust coming out the back?

 

[Belizean]

Oh yea. Twice pipes, they do look and sound better. Maybe a little more of a chance to get hung up on the ruff stuff. But if it is just a road vehicle, no problem.

 

[Manic Mechanic]

as stated in the pm i use headers because one they were already on there and two when I smash the exhaust pipe on the rocks (hey it happens) the headers are more forgiving than the one piece cast iron exhaust manifold. however if its just a looks and sound thing for a street vehicle then hey the customer is always right

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[PRM]

as stated in the pm i use headers because one they were already on there and two when I smash the exhaust pipe on the rocks (hey it happens) the headers are more forgiving than the one piece cast iron exhaust manifold. however if its just a looks and sound thing for a street vehicle then hey the customer is always right

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Manic, I also sent a pm.
Is this the carb I should buy? http://www.2040-parts.com/motorcraft-2100-jeep-carb-upgrade-258-4-2-non-smog-1-08-i1324354/

What HEI do you prefer? Is it a Summit Racing part?

 

[Manic Mechanic]

looks decent as long as its fully rebuilt. as for the HEI i prefer a D.U.I. unit or a GM unit with the gear changed out.

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[PRM]

looks decent as long as its fully rebuilt. as for the HEI i prefer a D.U.I. unit or a GM unit with the gear changed out.

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[PRM]

Is there another source that you prefer...or do you sell rebuilds?

 

[Manic Mechanic]

you can go with him. typically when I get them i buy em at swap meets then have them gone through. but what he has looks good

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[PRM]

Doing some more research on this and have a few questions. Regardless of intake, I will be purchasing headers (6-1).
1. If I were to go with a Holley Sniper BBD EFI, would I need a new intake manifold, or will the stock one work?
2. Is it worth paying 300 extra for ceramic coated headers?
3. The Clifford 6=8 seems to be the most economical route. I'm seeing some comments regarding QC of their products. Is this a universal problem, or isolated issues? Maybe this is a case of "you get what you pay for"?
4. DUI, Petronix HEI preferred?

I'm leaning towards the Holley Sniper EFI, especially if I don't need to replace the intake manifold.

Any insight from anyone who has experience with any of the above mentioned systems will be appreciated.

 

[007]

I believe your OE intake manifold will accommodate BBD Sniper just fine. Get the kit, not just the unit; you won't need much (if anything) else.

If you are intent on headers, ceramic might be a good option. You'll now have a TBI with electronics up there right beside your exhaust and with ceramic, you can wrap them to keep the noise down and push the heat out with the exhaust and not worry about rust so much from the wrap (water/condensation/etc.).