My documented TBI-to-Vortec 350 conversion!

[jdyates]

Haha if I ever do a motor swap, it'll be something worthwhile, like a supercharged LQ4 or a 5.3 with a few go-fast parts

 

[jdyates]

Bad news, guys. Got her all together and running, but I tightened the studs to the tbi adapter too much, and created a massive vacuum leak. I'm praying that the gasket doesn't screw up a valve, but we'll see.

On a positive note, she fired right up first crank, and boy did she SCREAM. Forgot to bolt the exhaust back on, so she started open headers. Lol.

Tomorrow gets a new square bore adapter, and we'll see how she runs...

 

[jdyates]

Also, doesn't seem to be the only problem. Timing is off apparently, forgot to set base and it chugs and idles high, and eventually when it calms down, it dies. Still diagnosing, but I know the gigantic vacuum leak is part of the problem.

 

[94Sierra4x4]

Also, doesn't seem to be the only problem. Timing is off apparently, forgot to set base and it chugs and idles high, and eventually when it calms down, it dies. Still diagnosing, but I know the gigantic vacuum leak is part of the problem.

Good to hear she fired up right away, yeah they sure surprise you when they fire up with open headers, eh lol
Fix that vacuum leak and set the timing and get back to us!

 

[jdyates]

Alrighty, changed the oil, fixed the tbi studs, and got a thicker, more durable carb gasket. We'll see what happens!

Need to get new exhaust donuts, though, she's burning off all the carbon and remainer of coolant in the exhaust, and smokin like crazy put the flanges and muffler

 

[jdyates]

For those of you still following, here's a video of the first test run. A few things to point out:

-That thing in the bed is the hood
-It's loud as hell because there are no donuts in the exhaust flanges, getting them tomorrow.
-The idiot driving, yeah that's me. Lol.
-The loud whining is a vacuum leak under the TBI adapter.
-Still breaking it all in and cycling oil through, so I didn't think it was a good idea going further than the driveway.

http://www.youtube.com/watch?v=gv_BqYfCzSY

At this point, just need the exhaust donuts, and fix that damn leak. The leak is between the intake and carb-to-tbi adapter. Anyone have any ideas? All four bolts are really tight, and the gasket I used is thicker than the one that came with the adapter (which the motor tore up right away). Still has the leak. Sprayed carb cleaner, and that's the only leak I have, and it's LOUD.

 

[jdyates]

Let me specify a bit on the vacuum leak.

The adapter plate is bolted onto the intake, with four bolts, spread in the square-bore pattern, like this:

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I made the mistake of tightening all four as tight as I could, and that causes the corners to be more snug than the middle of the adapter. If I look under the adapter, I can see a TINY crack in between the gasket and adapter, and sprayed carb cleaner and sure enough, that's where it's leaking from.

Not really sure what to do. Should I loosen the four bolts so that the corners don't sit lower than the middle of the adapter? Is there a way to seal just that side? (the other three sides are fine).

Also, the new gasket I got is thicker (about 2mm or so) than the trans-dapt one, and still have the problem. Any ideas?

 

[FastOrange]

i would use two gaskets, and dont overtighten the plate. thats my best guess.

 

[jdyates]

Hmm, didn't think of that, I'll try it tomorrow! Great idea, man. I'll pick up another two and start over. Maybe even stack all three. Couldn't hurt at this point.

 

[FastOrange]

Hmm, didn't think of that, I'll try it tomorrow! Great idea, man. I'll pick up another two and start over. Maybe even stack all three. Couldn't hurt at this point.

deff wouldn't hurt, i heard these plates sorta suck and tend to get warped.