1970 GMC Jimmy engine replacement

[terryggoround]

I have a 1970 GMC JIMMY and my engine threw a rod the first time I took it out after a frame and axle shop had it for 2 months(had the front and rear end rebuild also all the body mounts and bushings replaced). The shop was supposed to balance the drive line and replace all the u-joints but was not done as I was 60 miles from home when the drive line came off the yoke at the transfer case. When my husband and I used some bailing wire to tie up the driveline and then he got in to put the truck in 4high only to find out it was already in 4high(the wrong boot is on the shifter and it covers the whole shifting plate). I thought when i picked up the jimmy from the shop that it seemed like the clutch was a little more torquey the normal but i thought it was just because i had not driven it in 2 months. After getting the jimmy back to camp i took my husbands 85 jimmy and the driveline home and back to the frame shop. The owner who was the one who worked on my Jimmy was not there but the shop took the driveline and said they would have it ready in 2-3 hours. This was a friday and I was very angry that I was not able to talk to the owner as he was out on service calls the whole day but the shop called me in 3 hours and i was on my way back with the balaced driveline with new u-joints. The shop also did not charge me a dime. That told me that my driveline was not balance and the u-joints were not changed when the rear end was being worked on. To make a long story shorter I got back with the driveline got it back in my jimmy put it back in 2h and took for a test drive. The jimmy ran fine or it seemed so. Later that night I was getting ready to come home checked all the fluids ect everything was fine. On my way home(30 miles to go) the truck starts loosing power and what sounds like loud static coming from truck then i hear and feel a loud bang and black smoke is pouring out of the engine compartment. The flatbed tow truck driver said that I might have blown an oil line cause there was alot of oil all over the ground behind my truck. I was sure in my mind that it was more than that.so after getting home and the jimmy unloaded I grab my flashlight and had a look. what i found was one hole (about the size of a 1/2 dollar)on each side of the oil pan with one of the parts that hold the piston to the crankshaft sticking out. I only bought the jimmy in January of this year and had only put about 150 miles on it after getting it home from Fresno(where I bought it) I had been told the motor had been rebuilt and had only about a thousand miles since.
Now i have been looking for a motor a crate or rebuilt. Have been told that a crate motors with EFI are about $1500 to 2500.00. But I want the same motor it came with that has a carb not EFI. The motor it came with is a 350 v8 5.7l with a 4 speed manual transmission. The transfer case is a Np 205. I have talked with a few online engine rebuilders and have been told they don t have anything in stock.
Any suggestions? I want my jimmy running again and soon before the rain starts. The one place that had a crate motor in my budget was Sims racing but that engine has EFI.
Thanks for your help from a fairly new 70 Jimmy owner!!

[asolde]

Well Congrats on the Jimmy and welcome to the fourm. Lots of information here. Some of these guys know these trucks like the palm of there hand. Best engine deal out there is the Jegs performance 350 260hp for $1510 on ebay with free shipping to your door! If you watch it for awhile they will drop the sales price. I got mine for $1200! Can't beat that deal with a stick!
Chevrolet Performance 10067353 GM Goodwrench 350ci Engine

[landy]

Asolde has good advice. A new motor with warranty is going to much more reliable, likely last longer, and be a better performer than one from a rebuilder. Probably won't find a better price than the Jegs deals.

[terryggoround]

asolde and landy;
Thanks for the info!! Now I can get my motor and get my baby back on the road again. I have gotten so much info and help from this site and very fine people of this forum with almost everything that needed to be done when I got my jimmy. Learning the hard way that having a shop (so called experts) doing some of the work was quicker than I could do it but the details is what makes a job good or a job done great. I like the latter as a great job will last longer because of that extra detail that only a person who really cares about keeping these classics on the road would take.That little bit of extra time in doing is hard to find when you pay for service. oh well every mistake is an opportunity to learn. Thanks again!

[Dale99]

Aslong as your getting a.... short block? You can put the carb onto the top of it. The biggest thing you will need to look at is the bolt pattern from intake to heads. There are 3 main patterns......

1 is easy to spot.. vortec. It is 4 bolts each side. Used around 1996-2000'ish.
Next, There are 6 bolts per side, all bolts go at the same angle. 1985'ish and before.
The other, 6 bolts per side, the two middle bolts are at different angles then the other 4. 1986-1995'ish

Anyway, cams are slightly different between carb and efi, but you can put a carb on top of an efi cam and tune it to work. I would also suggest getting whats called a roller block.. it will accept a roller cam. From the outside once its all bolted together, you cant tell. But less friction and better reliability.

[70cst]

Hey terryggoround ...

to the site and from Ohio

[terryggoround]

Dale99
Thanks for the info. I didn't know that a carb could be put on an EFI. Is it hard to do? And
will it work with the 4sp man trans?

[Dale99]

Its usually just a matter of swapping intakes, which is why I mentioned the different bolt patterns.

Depending the block, you may have to wire up an electronic fuel pump, because some of the blocks are not machined for the mechanical one.