need some advice

[87 jimmy]

hello, i need some help with my jimmy. it has a 305 in it now and i would love to take it out and put in a 4.5l cummins. the only problem is iam not sure if it is worth it, i would try and do most the work myself. the frame looks to be in good condition(would probley have to box it out) and there are no major problems besides the gas guzzling engine and the 700r4. iam just worried that the cummins will be to heavy, or it wont be able to handle the tq. all questions and comments welcome thanks alot. Adam
p.s i will be useing the truck as a daily driver, the only thing i will be towing would be my 18ft boat. and i would use it for hunting,fishing and off roading to.
(305,700r4,np208,10 bolt front and rear 28 spline, weights 4800lbs)

 

[gotblazers]

well let me start by saying welcome to ck5, Always glad to see other newbies besides me (makes me feel less like the oddman out )

i dont have any experience with diesel swaps so this is just my brainstorming but...

i doubt you would save money in the short term from swapping to a diesel because you would need
1.diesel motor complete with the computer and sensors
2.heavier duty transmission meant to work with a diesel
3.stronger axles to take the increased torque
4.whole new fuel system (gas tank,fuel lines,filter)
5.box the frame to take the extra weight
6.with a boxed frame youll want heavier springs to handle the increased pulling capacity.

its quite a job,but it would be sick for sure

Most diesels use dana 60's,14 bolts,dana 70's and higher so i dont know about those 28 spline 10 bolts.

my suggestion would be and again i have no experience with this, its just from my resesarch i would think you could...
with the 700r4 you have over drive and a low first gear so couldnt you just regear your differentials lower and get all the torque you need for pulling the boat. maybe 4.10 or 4.56? idk how low you can go on those 10 bolts.

 

[87 jimmy]

hey thanks for the reply. ya i knew it was gonna take a lot of work to do this kind of swap, i was even thinking just to get rid of my k5 and buy a diesel one but the one i have is in really good shape. i know i guy that has been collecting trucks for about 13 years rangeing from early 1920's to present and he has alot of k5s, burbs and other things most of which are diesels. so i figured i have most of the parts i need springs, 14bff, engines ect. as for electronics those would be harder to find but not impossible.
and this wouldnt be a 3 or 4 month thing. i would take a while till i get her perfect. is there anyone that knows of mabey a different diesel engine(a lighter one) that i could drop in. i was thinking 3.9L cummins or the 4.5L i think they weigh around 500lbs?

and it would be awsome to hit the gas and see the truck puke out black smoke into the convertible beside you. not that i would ever do that

 

[tRustyK5]

4BT swap has been done, and there are a few guys here that have very good knowledge of the swap. Check the diesel forum, some of it is pretty recent.

OTOH you could do a simpler swap and get near enough the same results...by dropping in a 6.2. That swap is all factory stuff that bolts right up.

Upside is a smoother quieter engine, same or better power (stock vs. stock) and weight is about the same. No adaptors to deal with, 700R-4's came stock behind them, and they're relatively cheap to source.

A NA 6.2 in a K5 would have no problem towing an 18 foot boat. My 6.2 pick-up towed our 17 foot boat like it wasn't there...and it regularly gets 23-25 mpg freeway.

Rene

 

[gotblazers]

Hmm a 6.2 diesel does make sense since they came stock in the military blazers. Although i seem to remember about hearing major problems with 80's chevy diesels, something to research before you pick a motor for the swap. Also if your friend has diesel running vehicles he has some kind of computer or injection system (assuming its new enough to use computers) as im 99.9% sure that diesel motors never ran with a carburator so if hes willing to help you out with the rest of the parts, he should be able to help you out with the computers too assuming hes willing to sell them to you . If you do this make sure to do a build thread.

again take what i say with a grain of salt as i dont have any hands on experience with diesels im just regurgitating what i've read .

heres a build thread that might interest you
http://coloradok5.com/forums/showthread.php?t=272000

 

[tRustyK5]

The 6.2 is completely mechanical as far as the injection and stuff. It requires one 12 volt power wire to make it run...no computer.

The early GM light duty diesels were based off the Oldsmobile 350, and they did have a bad reputation. The 6.2 came after the 5.7 olds version had already scared a lot of people away from diesel. Even today, some 30 years later the 6.2 gets tarred with the same brush the 5.7 did and there is a lot of confusion.

The 6.2 is actually quite a reliable engine, and is quite good at what it was designed for...light duty use and excellent fuel economy. The one in my shed has 240,000 miles on it...still ran good when I parted the K5. The one in my 83 pick-up has about 140,000 miles and still runs like a champ.

I swapped one into my 81 Jimmy in 2002 in place of the 355 it had. Not a hard swap at all, and suddenly I could afford to drive it again. I was always happy with the power it had, the 355 it had wasn't much faster.

Rene

 

[gotblazers]

The 6.2 is completely mechanical as far as the injection and stuff. It requires one 12 volt power wire to make it run...no computer.

The early GM light duty diesels were based off the Oldsmobile 350, and they did have a bad reputation. The 6.2 came after the 5.7 olds version had already scared a lot of people away from diesel. Even today, some 30 years later the 6.2 gets tarred with the same brush the 5.7 did and there is a lot of confusion.

The 6.2 is actually quite a reliable engine, and is quite good at what it was designed for...light duty use and excellent fuel economy. The one in my shed has 240,000 miles on it...still ran good when I parted the K5. The one in my 83 pick-up has about 140,000 miles and still runs like a champ.

I swapped one into my 81 Jimmy in 2002 in place of the 355 it had. Not a hard swap at all, and suddenly I could afford to drive it again. I was always happy with the power it had, the 355 it had wasn't much faster.

Rene

well damn Rene when you put it like that i wanna do a diesel swap now

 

[87 jimmy]

hey thanks for all the info guys. i think i am gonna go for it, and i will post alot of pics too.

 

[gotblazers]

hey thanks for all the info guys. i think i am gonna go for it, and i will post alot of pics too.

nice! I'll be lookin out for that build thread. You gonna post it in the garage or here?

 

[87 jimmy]

i will post it here, but not for a while. i think i am gonna start on it in the winter time i got a 24x24 heated garage and one of my friends has a big shop that i could work in. the first thing iam going to work on would be the floor boards there are two small holes, and the seat brackets are rusted to ****. and i will post alot of pics for you guys. thanks again everyone.

 

[cabledawg]

Rene, what are the specs for hp and ft-lbs on a NA 6.2? If its as easy as you say, I might try it with the wife's Burb. I wanted to do a detroit 3-53 or 4-53, but if a 6.2 is really that simple, I'll go that route.