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The vehicle is a 1988 2.5L MJ, with the throttle body injection. If anyone has priced that injector, it's crazy what they cost. I'm starting to consider a backwards conversion, to a carburetor instead of TBI. Not sure, but I think I can leave all the injection wiring intact and unused, and continue running the factory Renix ignition setup.

 

Does anyone know anything about sizing carburetors? My numbers indicate that at 5,000 RPM a 2.5L engine nominally flows 220 CFM. I'm accustomed to 4-barrel carbs on V8s, running in the 550 to 750 CFM range. I'm guessing for normal street driving and economy, I should be looking for a carb in the 250 to 300 CFM range. Does that sound about right?

 

One barrel, or two barrels? Does anyone offer a small 2-barrel carb that's set up like half a 4-barrel, with a small primary venturi for economy and a larger secondary that opens when the engine needs more air?

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Wasn't the AMC 2.5L engine carbed until 1986 when they got TBI? Should be pretty easy to find an 85 or below 2.5L carbed engine or the carb/manifold parts you need that were removed when someone upgraded their CJ or something to fuel injection, si? As I recall, the 85 and below 2.5 carbed engines had a simple one barrel Rochester carb.

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As I recall, the 85 and below 2.5 carbed engines had a simple one barrel Rochester carb.

Yes, they did. And the carb was widely regarded as a piece of [bleep]. If I go ahead with a carb conversion, I may seek out an '84-'85 intake manifold, but that's one carburetor that's not under consideration.

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Reverse upgrade=Downgrade dude, no carb could be as accurate as FI. If you need a new part but it's too pricey, maybe try a used replacement for less?

Easy to say. What's the best fuel mileage you ever heard of from a 4.0L XJ or MJ? Low 20s -- maybe? I got 28 MPG on a road trip in my '88 XJ 5-speed when it was fairly new -- ONCE. Must have been a helluva tailwind, because I never got mileage like that again.

 

Go back 20 years. I had a 1966 Rambler American, 3-speed, no overdrive. No fuel injection, just an old-fashioned 1-barrel carburetor. I routinely logged 28 MPG for highway mileage in that car. And a Rambler American wasn't any more aerodynamic than an XJ.

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I was going to suggest this very same carb setup.  the 32/36 DGEV is a good carb replacement for mid sized (2.3-2.6ish) 4 pots in truck applications.  We just used one on a buddies old Nissan Pickup with a 2.4 because the factory carb (an overly complicated electro-smog thing that costs $1100 rebuilt) needed replacing.  His truck runs great now and gets pretty decent mileage too.

 

Honestly, I've considered reverting my 4.0L to a carb more than once.  I have a wideband sensor and gauge sitting around and a bung in the exhaust for one, so I could really get that thing fine tuned.

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It's a Chevrolet injector, same one used in their TBI trucks. Shouldn't be more than 40 bucks.

http://www.autozone.com/fuel-delivery/fuel-injector/jeep/comanche-4wd/1988/4-cylinders-h-2-5l-tbi
Its just going to a home screen. Here's the reman ones. 1ba14aaabd67c1d67d5f9a163b56202b.jpg

 

www.partsgeek.com/gbproducts/MC/3126-07142055.html?utm_content=MC&utm_term=1989-1993+Chevrolet+Caprice+Fuel+Injectors+GB+Remanufacturing+831-14114+89-93+Chevrolet+Fuel+Injector+1991+1992&fp=pp&gbm=a&utm_source=google&utm_medium=ff&utm_campaign=PartsGeek+Google+Base&gclid=Cj0KEQiAg7ayBRD8qqSGt-fj6uYBEiQAucjOwWOJvK0dN-ktu9AvReZdy2XsXR3Eei-yddu2-WS6BlEaAvCq8P8HAQ

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I'd sure love to see how a 4.7 Hesco built stroker would perform with dual Webers.

 

14308530143421385624874.jpeg

 

There was a member, Stacks I think, who was building a stroker with Clifford go-fast stuff. Anyone know what happened to him? I was very interested in his build.

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