Swapping a Iron Duke to a 350

[Super8mm]

I found out recently while running up and down the coast of NC that that Iron Duke is not really a highway engine

I am pondering getting a Chevrolet Crate Engine and was wondering if anyone has used them and what sort of luck did you have?

Also did you go with carburetor or something like FiTech EFI?

Thanks

 

[RiverandSand]

I have ZZ4 350 crate motor in mine. It's been just awesome so far. I replaced a tired 305 which a PO installed at some point. My jeep also started life as a 4 cylinder too. So you have a gm bellhouseing and hydraulic clutch to work with. I would look for a different trans however as the SR4 isn't very strong.
While this conversion isn't cheap it is well worth it. IMHO
If you are mechanically inclined (should be if you own a CJ) you can save a lot by doing it yourself.

Novak Conversions has wealth of knowledge on these conversions and parts to get the job done. I highly recommend it.

Also do a search of this site, lots of info on here too.
Good luck

 

[Super8mm]

Thanks RiverandSand, I have already picked up a pair of Muncie SM465's and they are complete with bell housings.

are you still using a carburetor.

 

[RiverandSand]

are you still using a carburetor.

Yes, a Holley 750 (3310). I have been looking into the Holley Sniper EFI units and a few others. Still have other projects on the CJ I need to address first. EFI is on the list though.

 

[Kane]

I ran a Holley 670 truck avenger and a Rochester Qjet on my 350. Both had their strong points. The qjet was more driver friendly with the small primaries and idled much better. The Holley gave the motor more low end and top end power but drive-ability wasn't as nice. The qjet lost steam around 5500 RPM while the Holley just pulled strong all the way to redline.

 

[Manic Mechanic]

i put a 6.2 diesel out of an 86 hummer into a 89 yj i went with that one b/c its size was based on the small block chevy then i added the intake and turbo from the 6.5. the nice thing about this set up is its all mechanical. i went with the sm465 and np205 transfer case. of course then i had to change axles but thats for another post.

those motors can be had very cheap heck even free sometimes and a diesel gives gobs of low end torque but still provide almost 20mpg and being based off the small black chevy all the conversion parts from novack work for it like a charm.

 

[Super8mm]

i put a 6.2 diesel out of an 86 hummer into a 89 yj i went with that one b/c its size was based on the small block chevy then i added the intake and turbo from the 6.5. the nice thing about this set up is its all mechanical. i went with the sm465 and np205 transfer case. of course then i had to change axles but thats for another post.

those motors can be had very cheap heck even free sometimes and a diesel gives gobs of low end torque but still provide almost 20mpg and being based off the small black chevy all the conversion parts from novack work for it like a charm.

Interesting concept, are all the GM 6.2's based on SBC??

 

[Manic Mechanic]

The original 6.2 L (379 cu in) diesel V8 was introduced in 1982 for the Chevrolet C/K and was produced until 1993. The 6.2 L diesel emerged as a high-MPG alternative to the V8 gasoline engine lineup, and achieved better mileage than the General Motors 4.3 L V6 gasoline engines of the 1980s, at a time when the market was focused on power rather than efficiency. However, it was designed to easily install in place of the gasoline V8, using the same mounting and attachments for transmissions as all GM truck engines. Overall weight for the complete engine is slightly heavier than the 7.4 L gasoline engine.

read the full info here (Link)-> Detroit Diesel V8 engine - Wikipedia -<

 

[Super8mm]

Thanks MM, good read

 

[Manic Mechanic]

the biggest issue i ran into with that swap was when i went to fire it up the first time i forgot that i sourced a military engine not civilian so it was 24v not 12v easy fix though

 

[Super8mm]

the biggest issue i ran into with that swap was when i went to fire it up the first time i forgot that i sourced a military engine not civilian so it was 24v not 12v easy fix though

will it motor down the highway at 70 and not sound like it is ready to explode like my 4 cyl?

 

[Manic Mechanic]

will it motor down the highway at 70 and not sound like it is ready to explode like my 4 cyl?

yes but so will any "good running" motor that you drop in if you want the easiest and most cost effective engine swap put a 4.2l inline 6 in. with the carb and removal of emissions B.S. you can drop it in and not really have to change anything. infact depending on your transmission you dont even have to change that just the bell housing. also they are cheap and plentlyful in junk yards peoples back yards etc. i got my last 4.2 (spare one) for free b/c the guy was tired of tripping over it and moving it around his garage. i know of another one the guy will let go for 100 bucks, just a little food for thought if you are on a budget and want save a few bucks yet be reliable and easy to work on.

 

[Impory]

I’m not at this point yet..but is there more info here on dumping all the emissions garbage...I sooooooooo want to do it...won’t affect anything here in Canada..

 

[Super8mm]

Thanks MM, I have to change the transmission anyway as the SR4 is jumping out of 2nd and the syncros are about gone on 3rd and 4th. I have already picked up a pair of SM465's with bell housings.

I am just unsure about used as I dont know how used "LOL"

Summit has a 350 290 hp Chevy Crate Engine for $2900. is short a carb, starter, water pump and distributor, headers and fly wheel. I would probably have about $4200 in that but I also found a 5.3L vortex with complete wiring for injectors, a auto and transfer case but is has 92k on it for $1900. this would probably only require headers, flywheel and radiator and i could probably sell the auto and transfer case?

 

[Super8mm]

Well darn internet, I was looking around and found a LS1 from a 2000 vette complete with wire harness and everything for $2250.

This one is alum block and heads so it is weight saving, and runs on Reg unlead.

 

[Manic Mechanic]

keep in mind motor and trans is just one part of the equation you still have to adapt the parts and if you are going from auto to manual then you need to change out and add a clutch and pedals. most dont realize how fast all the small things add up on a engine swap like motor mounts wiring carbs (if you go fuel injection add for new fuel pumps and lines) adapter plates drive shafts as they will change as well skid plates. the list goes on and on and on. a typical swap will run you 2k in parts not counting motor.

my 85 was a 4 banger i sourced a rusted crusted 6 banger cj with no title for 300 bucks rebuilt the motor myself and sense the rest was factory it was just a matter of moving parts from one jeep to the other. then i sold what i didnt need and what was still salvageable to recoup the money for the parts jeep.

P.S.
Impory
pm me for more info but in short change the carb (mc2100 is best opition) and put a gm H.E.I. ignition. remove all vacuum lines except for power brakes (if you dont have these get them yj (87-95) is a cheap source) vacuum advance for distributor and pcv valve. get an open element air cleaner plug all ports in intake including the egr below the carb. ( i had a block of aluminum machined into a fancy block off plate but simple 1/8" plate steel works fine and rtv for a gasket. then you can drop the computer from under the dash as its no longer needed and that will eliminate half of you wiring harness. there are a few other things as well. heres a pic of my engine bay with a lot of the BS missing
https://www.jeep-cj.com/forums/photo_popup.php?e=vB_Editor_001#

 

[Super8mm]

I went ahead and got that 5.7 LS1, it is complete from pressure plate to water pump with the FI and its harness and puter. one of my SM465's should bolt right up to it so I will still have to get an adapter for the transfer case, headers and motor mounts. I will get the harness and puter redone to get rid of the stuff I am not going to use and then a radiator and fuel pump

 

[RiverandSand]

Nice find and good choice. Novak has a whole section on installing an LS into the CJ.
Unfortunately you may have to change the output shaft on the SM465 (depending on the year) order to mate it to D300.
I know will be following your build progress, remember it didn't happen unless there are pictures.

 

[Super8mm]

Nice find and good choice. Novak has a whole section on installing an LS into the CJ.
Unfortunately you may have to change the output shaft on the SM465 (depending on the year) order to mate it to D300.
I know will be following your build progress, remember it didn't happen unless there are pictures.

I will have to either change the SM465 or the Dana 300. I am leaning to changing the Dana because I have 2 transmissions. I will rebuild both the trans and transfer case before i bolt up the motor. i may have to move the Atl and PS pump too.

 

[danop007]

yes but so will any "good running" motor that you drop in if you want the easiest and most cost effective engine swap put a 4.2l inline 6 in. with the carb and removal of emissions B.S. you can drop it in and not really have to change anything. infact depending on your transmission you dont even have to change that just the bell housing. also they are cheap and plentlyful in junk yards peoples back yards etc. i got my last 4.2 (spare one) for free b/c the guy was tired of tripping over it and moving it around his garage. i know of another one the guy will let go for 100 bucks, just a little food for thought if you are on a budget and want save a few bucks yet be reliable and easy to work on.

Can you elaborate on this I’m currently in a situation where I have a Duke with a work/out of round crank on a swamp buggy build. I’d rather upgrade to something a little more capable without braking the bank. I was looking at the 5.7 but if a 4.2L will be cheaper and easier I’m all ears.