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Old 02-28-2012, 10:31 PM   #1
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built 4.2

Has anyone actually built up a 4.2 engine. Actually made it have some power

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Old 02-29-2012, 07:01 AM   #2
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I've heard best thing to do was swap a 4.0 head and fuel inject it and add a cam. I wanted to do this but I couldn't wire up the fuel injection and it'd be expensive lol

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Old 02-29-2012, 07:53 PM   #3
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I put the Howell fuel injection on mine along with a Pacesetter Header and a good exhaust. It isn't a V8, but it is definately a big improvement over stock.
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Old 02-29-2012, 11:28 PM   #4
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Those r both probably good but I mean bore out. 60 over new pistons prormance head can lifters intake stroked and probably fuel injected I mean built
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Old 03-01-2012, 06:00 PM   #5
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mine is stroked. its a 4.5. i bought it that way though. its a 4.0 block, 4.0 pistons, and 4.2 crank and rods. it has the stock 4.2 head because the guy left it carb'd on the stock intake with a weber carb. it was a dog when i bought it so i have been trying different combinations of fuel delivery for better power. i swapped hte carb for a holley two barrel and its ok. i have an offy intake i am getting ready to put on with a motorcraft carb and i will see how that goes. i also have a 4.0 head in the shed with the injectors, throttle body, 99 intake, and the dual exhaust that someday might go on.

right now it will accelerate pretty good. i don;t have to worry about anyone rear ending me and i can tow fine
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Old 03-01-2012, 08:41 PM   #6
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You say it was a dog, who ever built it may not have milled the top of the block, with out cutting the block down [about .040" ?] the pistons well be too low in the holes and compression will be real low.
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Old 03-02-2012, 04:24 PM   #7
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that must be what happened because i can see the outline on the ledge where the head sits from the old head gasket. that explains it pretty well then because i am not impressed with this stroker and have been considering replacing it with a v8 for a while but if all it requires is the block milled then maybe i need to do that first. that would explain the horrible gas mileage and me not being able to get over 20" of mercury on the vacuum gauge in idle, no matter what i do
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Old 04-09-2012, 08:43 PM   #8
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I've got a 95 4.0 and I'm looking at installing a 4.2 Carburetor and Intake Manifold on it. Do you know if this is possible ? and if so can I disconnect the computer ?
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Old 04-09-2012, 08:55 PM   #9
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Quote:
Originally Posted by 93 SAHARA
I've got a 95 4.0 and I'm looking at installing a 4.2 Carburetor and Intake Manifold on it. Do you know if this is possible ? and if so can I disconnect the computer ?
You'd have to swap the fuel pump to the mechanical fuel pump. Better off swapping cranks to make it a stroker iirc
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Old 04-09-2012, 09:29 PM   #10
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as we speak I'm getting my parts together to build a Stroker, yes you do have to mill the top of the block, it's just a matter of the set up ,how to mill if your running a 4.2 head with out doing a lot of work on it your power will still be down. with the 4.0 HO head you need to mill the block to get the squinch area below .060" that mean to run right with the computer you have to get the compression down to low 8's or 9's IDK, I'm going with about a .050 squinch, around 10.25 CR a 4brl intake from 6=8, 390 Holley, a 268 Comp. Cam, headers, 1997 4.0 block, pistons and head, 1990 4.2 crank and rods.
It should have great power from 1,800 to 3,000 RPM, if you rev. it up should see about 265HP and 300+ TQ.
Oh, Bore .020 over, ends up a 4.6
If all goes as planed, Yes you can make power with a I-6.
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Old 04-09-2012, 09:38 PM   #11
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A 4.2 is a small bore long stroke engine, with a low RPM cam, 4.0 H.O. head and good after market intake like 6-8 makes, the right 2Brl. or 4Brl. Carb. and headers it will pull great on low RPMs, and that where it's needed for DD or Off Road.
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Old 04-10-2012, 05:28 PM   #12
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i put the offy intake on and it made it run better but this engine definitely needs some milling. it will have to wait though as i now have a 302/c6 to swap in.

until i swap it though, i am trying out all the carb combination's that people comment on.

weber 34= junk
mc2150 1.14= ok
holley economiser= great
next carb: holley 450 cfm four barrel= should be fun

the four barrel will go into the 302 once it gets dropped in. that is what i bought it for but until then, it will work fine on my 4.5, according to holley
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Old 04-10-2012, 06:55 PM   #13
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Maybe when you drop the 304 in the offy and Holly Carb will find its way to my house
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Old 04-11-2012, 04:17 PM   #14
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ha ha ha, i am not sure. my son wants a wrangler or cj for his first vehicle so if i can find one with a blown motor or bad tranny, this set up will go into his.

of course, if i can find a fuel injected model, then this will all be going to someone else.

you know the holley economiser carbs are on ebay for 20 bucks all day long. they have some electronic plugs hanging off them but i took all the electronics off and left them off when i did the rebuild on the one i have. they came on chrysler/dodge vehicles in the 70s and are a really solid carb. i didn;t have to rejet at all, just rebuilt it since it was sitting in a dude's shed for a few years and was all dirty. but the jeep ran like the carb was made for it and the carb came off a 360 or some other large v8. if you check ebay, the economiser doesn;t look like a normal holley because the body and bowl are one piece.
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Old 04-11-2012, 10:26 PM   #15
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Hmm I may check. I have the 2100 now its alright a lot better than the Carter lol
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Old 04-12-2012, 04:22 PM   #16
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yes, my mc2100 is better then the old weber 34 but not as good as that holley economiser, i know what you mean by alright
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Old 04-12-2012, 08:19 PM   #17
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Quote:
Originally Posted by busemans
yes, my mc2100 is better then the old weber 34 but not as good as that holley economiser, i know what you mean by alright
The economiser on eBay is 100 and 4barrel hm what car did you get it off? Mine wants to die when i mash the skinny pedal then bucks and goes its odd lol
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Old 04-12-2012, 09:09 PM   #18
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what?? a hundred?? holy crap, get a used one and rebuild it for cheap. mine were all two barrels. i got it off a 68 chrysler....... damit, can't remember hte model but i found another on a dodge pick up in the junkyard.

let me look and i'll find you one on ebay cheap.
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Old 04-12-2012, 09:10 PM   #19
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Holley 2 Barrel Carb | eBay

this is almost identical to mine
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Old 04-12-2012, 09:13 PM   #20
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Old 04-12-2012, 09:14 PM   #21
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dang, i just noticed that i am calling them economisers but they are not. sorry, that is what had you looking for the wrong model holley.
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Old 04-13-2012, 07:31 AM   #22
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Lol that's OK. Is it a lot better going Holley over mc2100? I could probably get one try to learn to rebuild it then sell mine and throw on the Holley I just can't get my jeep to stop bucking lol
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Old 04-13-2012, 05:01 PM   #23
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i like it more then the mc2100. its personal preference on carbs though. some people love motorcraft carbs or holleys or webers, or whatever. it just depends on what people got used to working on, really. i grew up on vw one barrels and the moved to quadrajets. after that i went to webers and loved those. once i moved to the jeep, i found out how horrible the weber 34 is and went in search of another carb and found that holley on craigslist for 20 bucks. it worked perfectly, like it was made for hte 4.2. i have ran it all over texas and towed a trailer across texas with that carb on the jeep and never had trouble. i swapped it on and off with different motorcraft carbs and they never ran as well as that holley did so i always put it back on. well, when it broke, i was stuck and since i had a few motorcrafts, i threw this 1.14 on. its ok but not like that holley.

my four barrel should be here monday and it will immediately go into the dip tank over night and then i will start rebuilding it tuesday morning. i hope to put it on sometime during hte week and will hopefully be able to report a great runner at the end of next week. i just have to figure a way to turn it 90 degrees on the intake so i can use my auto trans kick down linkage
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Old 04-13-2012, 10:11 PM   #24
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That's why I like my manual tranny easier lol. Yeah im new to carbs and so far they are a pain lol. I am OK with the mc2100 but I can tell its not meant for the Jeep. I just need to learn how to rebuild them lol.
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Old 04-13-2012, 10:19 PM   #25
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rebuilding is super super easy. get a nice spot and start taking it apart. put all the screws that hold the top on together. all the screws that hold the accelerator pump together, all the ones for the power valve together (same as the acc pumps ones though, exactly the same) then pull hte float out slowly and get the pin and little spring and lay them out. put the needle down ad unscrew the seat and put them together (new ones will be in your kit but i don;t get rid of anything till its back together) pull your jets out from the bottom of the inside of hte bowl. pull the little rubber umbrella looking thing from the side where the accelerator pump was screwed and also put hte pump and its spring down. undo the screw holding the emulsion tubes and annular venturis out of hte main venturis and lay them out. there will be a little bb in the center, under the screw so put that down too.

you are pretty much torn down now. put everything in the cleaner over night and have some cans of spray cleaner for when you pull it all out tomorrow and spray it all out and then lay out your picture instructions form the rebuild kit and put it back together but set the float properly. that is one important part. you measure from the end of the float for the distance form the top of the bowl to float. adjust your mixture scerws 1.2 out and your idle 1.5 out, and put it on and fine tune it with the jeep running

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