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first big block gas install in cucv.need wiring help

hokie8358

Member
87
0
6
Location
backwoods ,virginia
i have a 86 cucv m1028 i picked up at DLA in richmond va. a year ago. since then i ve put a 6in lift,2in. body lift and 39.5 swampers on 16.5x10 alum. wheels. i knew this set up would kill my 6.2 on top end! so i picked up a banks turbo from old grouch and installed it. well it helped out a little bit to build more horses,but still not enough to turn over that big a tire in deep mud!
i am first to say i try to keep something as close to O.E.M as possible,but i have to draw a line in the sand on this one! I picked up a built GM 502 CID. BIG BLOCK off craigslist.also with a hd th400 hooked to it for 1400.00!!!
its a 85 model and is in the area of 425hp. i am adding some GMPP alum. heads to boost it a little more! MY QUESTION WITH THIS IS---IF I USE THE EXSISTING DIESEL WIRING HARNESS FROM THE 6.2L,WHAT WIRES DO I USE FOR THE 502 AND WHAT WIRES DO I TRASH TO GET THIS SET UP PROBLEM FREE? ALL IMPUT WOULD BE GREAT!! PLEASE HELP AS THIS IS MY FIRST SWAP FROM DIESEL TO GAS!!! THANKS
 

Skinny

Well-known member
2,130
486
83
Location
Portsmouth, NH
Need more info like what fuel and ignition system are you running. Since it is an 85, I assume carb with HEI. Use the pink wire going to the injection pump to feed your ignition coil. That's it! The 6.2 doesn't have much useless wiring on it. I also assume you are converting to a 12v system, do it the same as if it still had a 6.2

Glow plugs and senders will come out because you probably want real gauges on a high horse engine.
 

hokie8358

Member
87
0
6
Location
backwoods ,virginia
Yes the ignition is a msd billet dist. And rebuilt 12 v starter.
Got a friend of mine who just landed a zz502/502 crate motor for his cucv but has not installed it. He picked it up for 3 grand! Only has 6000 miles on it. When i seen this one i snatched it up so i could
turn the tires over to get em to self clean to get traction. Kinda undecided on the intake and carb set up! Looking for the easy route to good 500+ hp! Lol
 

biggestc69

Member
228
1
18
Location
Council Grove KS
We always had a problem with the Gen 2 circut on my boss's 08. We beat our heads against a wall for weeks replacing parts and cleaning and replacing wires. Nothing. So we did the roscommon 12v conversion and got rid of the Gen 2 circut all together. 5 months later the 6.2 snapped the crank right behind #2 like most do. Jegs had a sale on 350 performance new crate engines for $1500 free shipping. 250 horsepower and around 380 torque. It is a hole new truck. You can't hardly give it gas without spinning the tires and as far as pulling goes this thing is a BEAST. Now I've got the fever and I think a little hopped up 454 is going in mine next spring. You can clean up some of the wiring, glowplugs stuff like that. Skinny is right pink wire to the injection pump is your key on hot for the ignition. The rest is just regular small block to big block swap stuff. Engine mounts exhaust, make sure you get all your brackets. After you tear into it there will be a dozen more things you'll notice right off the bat that you dont have. There was one member on here though I forgot his name but he left his 24 and dropped a 454 in. I'll check and see if I can find the post.
 

hokie8358

Member
87
0
6
Location
backwoods ,virginia
just got on here after long day at the lake! great info to work with and i would love to do the 24 volt system on the 502cid. that friend of mine thats doing motor swap is keeping the dual alternators and making his a serpintine set up with electric cooling fans. i would love to go that route. just ready to get it in there and let the throttle roll!!!!
 
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