I've had my 85 GMC Suburban K20 now for a few months, but she sits awaiting a new top end. I very recently also came into ownership of an 88 Chevy Suburban R20, and she runs great, under 125K original miles, you cant beat the steal of 800 I paid for her. I drove her home and my friends pathfinder who always jogs away from my 85 (when she IS running) couldnt even keep up with the power of a bbc. Which inturn, inspired me. Big Block TBI swap on the small block carbed 85. The 85s body is flawless, all blacked out, brand news trans and tc, and the rear end (semi floater 14 bolt) was rebuilt, though i'll probably swap out the rear end for the full floater in the 88.

What I want to know is, what exactly do I need to swap over, I'm already planning to drop the tank and fuel lines and swap them to the 85, as well as the wiring harness and the ecm and fuse block for inside the cab. The 454 came from the factory with TBI, as its an 88. This BBC is equipment with all sensors required for the swap. The exhaust will be done after the swap, as the new 350 exhaust thats currently on the 85 is hacked and not smog legal, so I will run a brand new manifold exhaust back (im considering true dual, if not, y-pipe to flowmaster big block exhaust, complete with the cat required for the truck to pass smog (4 inch piping)

I will of course swap over the brand new aluminum 4 core radiator that came in the 88, and from the TB all the way to the fuel tank, the whole fuel system will be swapped over to the 85. The only thing I'm really worried about is wiring the Fuse block as well as the ecm, but i believe the ecm is plug and play. I need to know about the plug in the firewall for the ecm as well as the wiring harness plug, do i need to swap the plug from the 88 to the 85, is there one already in the 85 that will allow for plug and play, or do i need to cut a hole in the firewall? also will the AC compressor on the 350 thats currently in the 85 bolt to the accessory brackets on the front of the big block to run the current AC? (the 88 is front AC the 85 is front and rear, the compressor on the 88 seems to be frozen up) can I also retain the power steering pump on the 85, or do i have to bring the pump thats on the 88?

I've searched many topics but cant find any detailed instructural how-to's on the subject. any input would be greatly appreciated, I love my 85, but the 73-91 suburbans 4x4 with a bbc and ff rear end is my dream truck has been for years, and Id wrather build my 85 into my dream them go buy my dream already realized in someone elses eyes. again, any information on the subject would be greatly appreciated. Thanks!

 

AAAAH Big Blocks not for the meek or the mild designed specificly for the completly and totally Wild!! Ya gotta love em !!! I would definently look into the total swap of all parts if its feesible and they are in good operating or reasonably inexpensive to repair.Not only will you be consistant in the build but the less mods.unless an upgrade the better !! what you need is wiring diagrams! for both models, so you can parts, component, match, check your local library they usually have make and model specific oem manuels on hand to copy, compare components, and part numbers, if you have a good parts supplier ,they should be able to compare for you as far as bolt up and compatibility, write it all down and take your time, Know your options such as carb the BB, slap on an HEI IGN. and you wont have to deal with all that extra stuff look into multiport vs. throttle body ,even more power! things of that nature, get one stripped and all parts in order, fix the problems now not later, from eng. mounts to exhaust to brake components, check gear ratio's measure frame clearances.and thickness check the pin points, the specs for these will be in a collission frame manuel. this is necessary as you may have to reinforce or modify frame components move cross members, measure driveshaft lengths goes much smoother on a mod. to have it all layed out and each system segrigated and compleatly investigated pick and pull junkyards are another good sorce for compatibility issues they can cross refrence as per application ,believe me, another good idea is to take lots of pictures for reference, todays digital cameras are great Also use the best and strongest of both, throw nothing away EVER! LOL you will need it sometime at least till the job is done and make it pay for itself and or the extra mods. that you may want to employ, you may want sell as you go i try to have the parts sold ahead of time, not only does it get rid of them and they are out of the way, but also funds that project, do your homework and you will be fine And i aggree building your dream is what its all about!! buying it slapping on some lights a tint job and some fancy wheels well it speaks for itself Nuff said !! good luck and let us know as you go HAMMERGONE!!