GM 4 cylinder

Is anyone runing the GM four cylinder motor,if so was their any noticable jump in performance.I know were talking 4 cylinders but my F head on propane and 34" tires needs alittle something.

 

The iron duke or tech 4 that carries the small block chevy bell pattern

 

Hmm. There was a 153 that came in Novas and postal Jeeps. There was a 151 (usually called the Iron Duke) which was mostly a Pontiac engine, but was also used in Cavaliers and S-10s IIRC. Both have the SBC pattern.

The 153 also has an industrial/marine version that is 3.0L or 181 cid.

I wouldn't bother with a 151 swap, unless it were already in the Jeep. I think the only thing they have going for them is they are really cheap to buy, and durable in some apps. However, the 153 is a great motor, essentially 2/3 (edit - not 3/4) of the 230 cid Chevy inline 6 - used in sprint cars a lot.

You could also consider the 150 AMC 4 (60 degree Chevy pattern), or the Pinto 2300.

All of these engines have more power than the F134, and tend to happier than the F134 at higher revs.

<edit> Just a comment about Sparky's comment - V8s are very old school in pre-72 CJs, and seem to me to have been almost universally displaced by the V6s. The V6s simply fit the engine compartment better. A 4-cylinder is even easier, and the Pinto is/was popular because it revs freely and the adapter is cheap - you use the original bell and T-90 input shaft. The 153 was popular, but it's probably more scarce now, esp. since the 181 seems to have gone out of production in the last year or two. You need a specific bell for the Pinto, and it hasn't been produced for decades, so that may be tough to find. http://www.film.queensu.ca/CJ3B/Tech/EngineSwaps.html

The easiest to source (other than the 151) is probably the 4.3L V6 and its variants, followed by the 231 V6 Buick.

 

I like the idea of the iron duke(151 or 153) in a Jeep. I have had the later model in later Jeeps. I would think with stock gearing in an early Jeep you'd definately notice an improvement if from nothing else than from the wider rpm range. I think maybe the Wrangler 150(2.5) might be worth a look also.

 

The tranny I'm running now is the T-18 so adaptation should be some what easier,I'm just looking for alittle more umph,but I'm sure all of use with the F head are just hate to lose the original jeep motor

 

We put a 153 in Dad's 43 GPW and it doubled the performance of the l-head.
It revved pretty good, had plenty of grunt for a flattie. It was stock with the 4.88 gears IIRC but we did put in a Saginaw 4 speed. It would do great with a T-90 or with your T-18. I have the 231 in my CJ-5 and really like it. The 4.3 is a great way to go, I'm putting a TBI version in my '68 when I get around to it. The 151 is not a bad motor if taken care of and pretty readily available. Had one in a Chev Monza with a 4 speed and it would do 105 mph (highway gears) and got great gas mileage. The pinto is a great conversion if you can find the bellhousing and adapter. They really survive at higher rpm. Any of these would work great. Only thing is the 4.3 is probably the most readily available. Just depends on what your end goals are for how much power you will need. Nickmil

 

Well so far thanks for the info,I have a 4.3,a2.8,and a 4 cylinder out of a fiero,I like the simplisity of a 4 cylinder,I no how good the 4.3 is,and I love my F head,just need alittle more grunt,I'm trying to keep things lite.I wonder if I had someone to regrind my cam for propane would give me what I'm looking for.

 

What compression ratio? I had thought you needed high compression with propane or LPG - this could be a problem with the F-head. Is there such thing as a turbocharged propane engine? You already have fairly low compression, and packing more charge in might be a good substitute for raising the compression. The F-head has a heavy block and steel crank and rods, so it should be strong enough to withstand some boost.

 

If your going to convert anyway the 4.3 is smart remeber its only 3 cylinders long.

it is also pretty light just makes the most sence if you have to buy conversion stuff anyway.

 

I'm not sure judging by the original color of the block it's the low compresion one,right now she run's pretty good when the pertronics works,but at idle I have a pop going on real intermitten.I have concidered shaving the head to raise compression but was unsure how much material to take off without having to do alot of test,concidered the cam regrind,Clifford's say's his guy could do it but wondered about the turnout.

 

Out of the three it'd be between the 4.3 and the 2.5. I'd probably end up with the 4.3 because it can make twice the power of the 2.5 with little effort and both are gonna be about as easy as the other to swap. But I sure like the simplicity and the idea of a four cylinder Jeep. I'm glad I don't have to make that decision...

 

Crud<kicking dirt>, another Fhead soon to be put out to pasture, just let us diehards in on your Fhead secrets before you go!

 

The flattie my buddy's dad built in 1980 was a Ford 2.3 with a Warn OD. prolly one of AA's first kits. Nice running Jeep! Hmmm, thinking now -- I wonder why he didnt go V6? must be long shaft trans were hard to find and Herm wasn't building kits. Interesting.

I'd say go V6 as you can scratch up parts though this forum and not spend anything on purchased new adapter kits. You can climb trees with a V6 + 5.38 8)

 

If you just want some extra power, and want to keep the F head, you could turbo it. It's been done before, and it seems like these motors could actually hold up to mild boost quite well (both F or L heads). I've thought about doing this some day in the future, just because it always seemed like a cool idea for extra power and a fun fab project (while keeping the original motor)...and because I play with VW diesels quite often and have turbo parts kicking around. This is a little off topic because you're talking about gm 4 cyl options, but here is a link to a thread with a member who put a turbo on his F head.

http://www.earlycj5.com/forums/showthread.php?t=29300&highlight=turbo

 

I have a Chevy II Nova 153 cubic inch 4 in my Jeep. It fits real nice and has plenty of power, the crank is supported by five main bearings and you can not hurt the bottom end with reving. If you want more power, they used this motor in boats (Mercrury Engines) this motor has 181 cubic inches and a better head. This is a great motor for a Jeep and makes the engine bay not clutered and easy to work on things. This motor shounld not be confused with the Iron Duke motor. It takes standard chevy parts and shares parts with the chevy inline six motor. I run this motor with 4:27 gears in my axles, and it buzzies downd the road real nice.

 

I'm running a marine version Chevy 153 which the PO installed, and I'm quite happy with it. Everything I've read about the motor indicates that it's pretty bombproof and stout. With 5.38's and 31's there's plenty of power, and I'm assuming there's more than enough for eventual 33's.

 

Those mercury 3.0's are plentiful around here. Good running condition for 5-600. I dont know what it takes to adapt though.

 

Up to this point I want to thank everyone for their input,As far as Iam concerned you guy's rock,thanks again.