1990 gmc van 350 into my 86 truck???

[Telecasterjoey]

Hey all, After lots of thought I think I'm going to scrap my van and steal the engine for my 86 c10! I plan on just leaving both trannys connected and just swap the engines and trannys completely. The van is a 1990 3/4 ton van with a 350 and a 700r4 with overdrive. The 86 c10 has a 305 with the th350. What problems will I run into? Can it be done with ease? I know anything is possible, but I mean Are they interchangeable? I plan on getting a new intake for the 350 and putting on a rebuilt rochester carb to eliminate the efi on the van 350, again will it work? I'm assuming I'll have to have my drive shaft shortened or find one in the pick and pull with a 700 tranny. Are the engine mounts and tranny mounts the same? Lots of questions I know! I'm just not sure if it will work.

Thanks! If I left out any details lemme know!

[Telecasterjoey]

nobody has put a later year engine in an 86? c'mon I know someones got some answers lol!

OR If the swap would be easier if I kept using my th350 tranny and just bolted the van block to it should I go that route? Easier question: Will my later year 350 bolt to my 86 transmission without problems?

[Pop's C-10]

yes..you will have to use a die grinder to angle tha 4 center bolt holes to match up with tha 90 heads..mounts are tha same..

[Telecasterjoey]

Thanks pops! What am I to grind? The intake? sorry maybe I'm missing something!

[rwhit57]

There's nothing unusual about this swap that's going to throw you any curves. You will have to wire up something for the lockup converter for the 700r though. I just did one and used a Haywire kit. I think Pop was talking about the center bolts for the intake, not sure what year they changed but they go straight down instead of an angle.

[Telecasterjoey]

Ok thanks! stupid question: What does the lockup converter do?

[MadManAndrew]

When you reach a certain rpm in a certain gear (or it maybe be a certian speed in a certain gear - ie. 50+ miles per hour in overdrive) it locks up the torque converter so that there's absolutely no RPM/Power loss from the motor to the tranny. When retrofitting it into an older pickup, a lot of guys just use a switch to lock it up when driving down the highway rather than going through the trouble of retrofitting a controller.

[DirtyLarry]

I used a 1990 G-van TBI 5.7L and 700R4 for a ’72 C20 a few years ago. Here is the story. And more to the story. Easy swap, I highly recommend keeping the TBI and start with a fresh engine harness instead of trying to made do with a 22 year old harness.

[Telecasterjoey]

Originally Posted by MadManAndrew

When you reach a certain rpm in a certain gear (or it maybe be a certian speed in a certain gear - ie. 50+ miles per hour in overdrive) it locks up the torque converter so that there's absolutely no RPM/Power loss from the motor to the tranny. When retrofitting it into an older pickup, a lot of guys just use a switch to lock it up when driving down the highway rather than going through the trouble of retrofitting a controller.

Thanks andrew! Thats kinda what I thought it did, but wasn't sure! thanks a lot

[Telecasterjoey]

Wow larry nice write up! Thanks a lot, This is the exact swap I wanna do. How hard was it took hook up the harness (vans) to the new trucks electrical? ( you make it look easy lol)
I was hoping to put a nice edelbrock intake and a re built rochester on the top but you think it would be much easier to just put use all the van stuff? Maybe it will make more sense to me when I get under the hood of the van, or should I say in the dog house lol
Now I might just keep it really simple and strip the van engine bare and hook up the 86 truck sensors and things to it (blocks should be the same right?)

My trusty van has 300000 kms lol but it runs strong and never burns any oil so I'm looking to do a budget engine swap and get my restored truck running right.

Thanks again your writeup gave me a lot more confidence!

[DirtyLarry]

Originally Posted by Telecasterjoey

Wow larry nice write up! Thanks a lot, This is the exact swap I wanna do. How hard was it took hook up the harness (vans) to the new trucks electrical? ( you make it look easy lol)
I was hoping to put a nice edelbrock intake and a re built rochester on the top but you think it would be much easier to just put use all the van stuff? Maybe it will make more sense to me when I get under the hood of the van, or should I say in the dog house lol
Now I might just keep it really simple and strip the van engine bare and hook up the 86 truck sensors and things to it (blocks should be the same right?)

My trusty van has 300000 kms lol but it runs strong and never burns any oil so I'm looking to do a budget engine swap and get my restored truck running right.

Thanks again your writeup gave me a lot more confidence!

WOW, that looks like a pretty clean van to pilfer parts from. I wish you lived closer as I need both lower control arms for my mom’s G-van.

As I mentioned, if you go the route of EFI, use a fresh TBI harness from one of several EFI harness suppliers. The 20+ year old G-van harness won’t be worth messing with as the connector will be hard and brittle. I used a Howell harness which was $400. Heck, you’ll probably get that much in scrap metal when you ditch the van body to offset the cost of the harness. It is a piece of cake going to TBI EFI and you will wonder why in the world anybody would want a carburetor ever again. The Howell harness is a simple plug and play install.

To do it right, you would need to install a ’87 fuel tank, ’87 TBI fuel sender (actually, I think you can use the G-van sender in the truck tank) and add an electric fuel pump to run the TBI EFI though. In fact, you’re going to need an electric fuel pump regardless as the 1990 G-van engine doesn’t have a mechanical fuel pump lob on the cam shaft anyway.

Another note, you will need to shorten the rear drive shaft when going to the 700R4 as they are a tad bit longer than a TH350. I had to on my ’72 C20 anyway.

Good luck with your project.

[rs72z]

Originally Posted by DirtyLarry

WOW, that looks like a pretty clean van to pilfer parts from. I wish you lived closer as I need both lower control arms for my mom’s G-van.

As I mentioned, if you go the route of EFI, use a fresh TBI harness from one of several EFI harness suppliers. The 20+ year old G-van harness won’t be worth messing with as the connector will be hard and brittle. I used a Howell harness which was $400. Heck, you’ll probably get that much in scrap metal when you ditch the van body to offset the cost of the harness. It is a piece of cake going to TBI EFI and you will wonder why in the world anybody would want a carburetor ever again. The Howell harness is a simple plug and play install.

To do it right, you would need to install a ’87 fuel tank, ’87 TBI fuel sender (actually, I think you can use the G-van sender in the truck tank) and add an electric fuel pump to run the TBI EFI though. In fact, you’re going to need an electric fuel pump regardless as the 1990 G-van engine doesn’t have a mechanical fuel pump lob on the cam shaft anyway.

Another note, you will need to shorten the rear drive shaft when going to the 700R4 as they are a tad bit longer than a TH350. I had to on my ’72 C20 anyway.

Good luck with your project.

He should be ok on the driveshaft, lenght should be the same just the trans mount is father back.

[Pop's C-10]

Yes..jus tha intake

http://www.73-87.com/7387garage/drivetrain/lockup.htm

[Telecasterjoey]

Will I be able to use the van fuel pump? where is it located?
Thanks

[Telecasterjoey]

Hey all, so I got the swap done! I didn't end up keeping the tbi nor the serp setup call me crazy but I want to keep it looking semi stock. I had to open up the 4 middle holes on my intake (I got an aluminum one so filing it was easy) other than that there were no major snags. I learned a lot as I went and believe it or not the thing fired right up tonight after I hooked rest of the stuff up!

here's a little engine bay before and after action!
Thanks

[motornut]

looks great
bet your gona hate not drivin it till spring

[Telecasterjoey]

Thanks! I know I should have done the swap in march lol, But atleast now I have the whole winter to figure out exhaust and all the other little things.

[motornut]

gona use headers or manifolds

[Telecasterjoey]

I'm planning on using headers. How much did it cost you to get those made up?

[motornut]

600. at midas

[Telecasterjoey]

geez thats not cheap, but I guess thats what it costs!

[motornut]

thats 4 sticks(pipes) , plus labour,all custom bent
and almost a full day on the hoist
mufflers i brought with me dynomax turbos

[Telecasterjoey]

I'll probably do the same, I was thinking about some exhaust kit for 300$ or something and welding it myself. but for the extra 300$ it would probably be worth it to have someone else do it lol. I've got two different sets of headers. one set is of of a car which I'd like to make fit because I hate the look of the headers hanging down below the frame
How hard would it be to order a kit to fit my headers?

[motornut]

midas did my 81 lemans (headers/duals to the back)
I drove it in open headers,lol no hood
you can just see the tip sticking out on the drivers rear
and all tucked up that was all you saw the tips at the back,or my dust
if you wana throw some manifolds on and use the front pipes to piss off the neighbours
get it runnin let me know i'll throw them over the fence lol

[Telecasterjoey]

Way ahead of ya! I started it up with just the manifolds on, I had to see if it would start lol. Surprised you didn't hear me from there!

Sweet lamans BTW!