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Old 03-07-2016, 09:01 PM   #5
Blessed66
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Join Date: Oct 2012
Location: Tyler, Texas
Posts: 217
Re: 1984 GMC (kinda) slow build, Part 1.

I warned you, this was a slow build. Unfortunately, a work situation made it a little slower, for now.

Small updates (no pictures, yet);

I picked up a brand new TBI HEI distributor unit for less than a bill and got that stabbed with minimal issue. I know I will need to set timing more than just by "feels good!" as a parameter, but the biggest challenge was just getting motivated (the aforementioned work situation) to get back on the horse and keep working on my truck. Stabbing a new, improved dizzy was a nice confidence booster.

I have also purchased a slick Trans Dapt adapter plate to mount the TBI on the QJet manifold. It's a solid, thick metal plate, mounts it over the secondary venturi location on the manifold. Full throttle plate opening and no binds. I cannot complain.

Also took this as a grand opportunity to pull the clunky stock manifolds and man, oh man... exhaust flange studs. Those suckers fought me until they broke, and I promise, that was not on the first try. The alleged exhaust in the truck now will be replaced (eventually) with headers (because, free) coming to a Y-pipe (because I require an O2 sensor), and something quiet with a decent rumble. It's not gonna turn a bunch of heads, but I want a decent sound, regardless.

I also removed the dash pad, and fed the OE 1987 TBI wire loom through the provided firewall hole (direct fit, gutted the original 6-7 wires that passed through originally).

For anyone taking an OE harness and retrofitting it, I cannot stress enough how simple cutting the extra wiring (that would normally go to the firewall junction beneath the wiper motor) off the donor harness. You end up removing the ALDL and MIL hook-up, but that can be relocated and completely reworked. I swear, it took about 1/3 of the wiring harness out of the cluster of wires I'm working with.

Next items, for those interested;

I want to drop the left fuel tank to ensure what size line is there, but I'm betting 3/8" and 5/16" with a smaller vapor line.

Order in Metric O-Ring to AN or hose barb adapters (for the TB supply and return lines), and run new hoses and a universal inline pump that meets the GPH and PSI requirements (spoiler, it's only $60).

Those two items are the bare minimum, I believe, to get the fuel system ready. I've seen the mention of a baffled EFI tank, but I don't believe it to be 100% required for this application. Running the stock pick-up/sending unit and gravity-feeding a 15psi (max) inline pump - I doubt it would be a major issue, even at 1/4 tank.

Still have some loose ends to tie up in sensors and EFI stuff (Coil, ESC Module, Knock Sensor, CTS, MAP, rewire for later-style TPS, figure out what I want to do about the EGR stuff, etc), but I just wanted to let you guys know it's coming along and I'm still here...

...now I just need a good job, for a change. But that's a subject for off-topic.
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Current Projects:
1984 GMC, LWB Fleetside, 305/350 - Currently Doing TBI Conversion
1966 GMC, SWB Stepside, 350/200-4R - Currently waiting patiently.
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