Engine swap: 86 carbed into 88 TBI

[GM72K10]

Recently picked up an 88 R30 dump, originally 350 4 speed 2wd, minus the engine. Donor truck (complete)
is an 86 C30 350 4 speed non TBI. Is this an easy swap where for wiring you just change the engine harness from the 86 with the 88? Or is there dash wiring involved. Remember, this is a dump truck, not a show truck or daily driver, so COST is the issue here. Any one done this? thanks for all the help. I see threads with conversions from carbed to TBI, couldn't find any in reverse.

[GM72K10]

Anyone?

[Russell]

Pretty easy swap!

Remove the fuel tank, and fuel lines from the TBI truck and install the 86's tank + lines to replace them. Next, pull the TBI wiring harness out. It is mostly stand alone, and should come out without cutting any wires, though you will need to undo a connector that runs to the ALDL connector and the dash bezel. You can leave the wiring beyond that installed. The engine side of the harness should be pretty much totally loose less the fuel pump wire. Bring it up to the front of the truck instead of cutting it after unhooking it from the fuel tank.

You will then have an 80% complete TBI harness + ECM you can sell on ebay to make up for the cost of anything you might have spent on the swap.

Install the carbed engine, the SM465 should bolt right up without any changes, run the fuel line to the carb, modify the distributer power wire that used to run to the coil (thick red wire) to the HEI cap, and switch the sending units from the TBI engine over to the new 86 engine, hook up the stock wiring, and everything should be good to go just like a regular old truck.

[tom coop]

ive got a 90 suburban with a carbed motor in it. it was like that when i bought it and the wiring was a mess, but it ran. i tried to swap out the harness bit theyre different at the firewall. ive heard its not that big a deal to change the wiring in the dash but im just gonna splice it all before the firewall when i figure it out.

[edman87]

ou are wanting to put a carbed motor into a tbi truck?
Why not keep the tbi system?
Just bolt on a tbi intake and tbi unit ( and heads preferably) and keep the reliable tbi.

[Russell]

More important than the heads, swap in an EFI compatable cam if you want to go the TBI route.

[GM72K10]

Thanks,
When i bought the 88 truck, the engine was in the dump body in the back, One of the heads was removed already, the intake off. All left outside. I plan on using the same 4 speed from the parts truck ( its got the pto plate) since that setup has a good clutch and is already mated to the donor engine. Taking it out and putting it in as one unit. thanks!

[GM72K10]

thanks Russell, more questions.
Are the tanks the same? Just changing the fuel lines, sending unit from 86 into the 88? Or do you have to change the tanks too? I take it there is a fuel pump in the 88 tank.
I removed the engine harness from the 88 and the ECM from under the dash, pretty simple. there was another disconnect from the dash that went into the ECM. What is an ALDL? Will dash lights and gauges work or do I need to swap gauges and wiring from the 86?
Also note that exhaust manifolds are different. Have to see if 86 exhaust will clear PTO unit. The 88 had single exhaust (crossover) and a converter. The 86 had what looks like factory duals with no converter. It too is a 1 ton truck but single wheel. Thanks again.

[hiway]

I had an 88 (half ton) with a carbed motor. I kept the pump, tank and fuel lines. Pump is only like 13 psi. I bought a $70 bypass regulator and set it at 6psi to the Holley. Used the factory return line to return the rest.

[GM72K10]

Putting the gas tank, fuel lines and engine in weren't too bad. Now to hook up the wiring and see if the 86's exhaust will work. BTW, did all 88 R/V series had cat converters for 10,000 GVW?