2.8L to 350TBI Wiring Questions

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2.8L to 350TBI Wiring Questions

Postby jester8798 » Mon Sep 11, 2017 8:07 am

Okay guys, I'm finally working my way through the wiring and am trying to modify my original 2.8L harness to work with my 350. Some of the connectors are pretty straight forward and things just need to be flipped from one side to the other (AC compressor, alternator).

There are a few others that I'm not sure what to do with. The oil pressure switch looks like it was on the driver's side near the oil filter on the 2.8 but the v8 is up behind the distributor. I don't have the best pictures from when I took everything apart years ago and haven't found much online. I can shorten wires to account for the new location but the connectors are different. Can I cut the connector out of a v8 and splice into my harness and use the v8 switch? Below is the switch I have.

https://shop.advanceautoparts.com/p/bwd ... l+pressure

I think this is what would have been on my 2.8.

https://shop.advanceautoparts.com/p/bwd ... l+pressure

Thanks!
-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
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Re: 2.8L to 350TBI Wiring Questions

Postby lowblazin94 » Mon Sep 11, 2017 9:38 am

Behind distributor is for your oil pressure gauge. Oil pressure switch can be added in the block above where the oil filter is. Just shorten the wires and use the same sending unit if it fits.
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Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Mon Sep 11, 2017 10:50 am

The issue is I don't have any of the original sensors, I sold the engine a long time ago and forgot to take better pictures and snag those parts for reference. From what I can tell I have a switch and sending unit on my truck which the first link above serves as both? To do what you mention above I'll need to put the single pin switch up behind the distributor and tie into the block by the filter for the sending unit (2 pin)?

Thanks for the help, much appreciated!
-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
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Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Mon Sep 11, 2017 11:08 am

I've been digging through photos back when I pulled the original motor and I have one looking at the driver's side of the block and there are two connectors coming out of the backside. One has two pins, the other looks more like the fat style with 3.

ImageIMG_2624_crop by Michael, on Flickr
-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
jester8798
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Re: 2.8L to 350TBI Wiring Questions

Postby lowblazin94 » Mon Sep 11, 2017 2:33 pm

Yeah i'm not sure how the 2.8 had it set up. One is just a switch so if it loses oil pressure it kills the ignition, other was for the gauge.

If you want to keep it with the switch tied to the ignition then I can find the diagrams somewhere. You're going with a carb correct?
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Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Mon Sep 11, 2017 5:39 pm

I'm keeping TBI. I could plumb one in behind the distributor and the other by the filter. Or would it be possible to tee them together?

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-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
jester8798
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Re: 2.8L to 350TBI Wiring Questions

Postby lowblazin94 » Mon Sep 11, 2017 7:40 pm

If you have room behind the distributor you could T it together
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Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Tue Sep 12, 2017 5:12 am

I'll give that a try first and see how things fit.

Thanks again!
-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
jester8798
My hoist hit me in the head!
 
Posts: 275
Joined: Thu Jun 13, 2013 10:25 am
Location: Lansing, MI

Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Tue Sep 12, 2017 10:23 am

Would it be possible to replace the connector on my original harness with one for this style sender?

https://shop.advanceautoparts.com/p/bwd ... l+pressure

The newer style is about half the price of my original style below.

https://shop.advanceautoparts.com/p/bwd ... /3991881-P
-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
jester8798
My hoist hit me in the head!
 
Posts: 275
Joined: Thu Jun 13, 2013 10:25 am
Location: Lansing, MI

Re: 2.8L to 350TBI Wiring Questions

Postby Rickracer » Tue Sep 12, 2017 12:52 pm

The older sender/connector contains a switch to kill the fuel pump if you should lose oil pressure. That sender is only $35 and change on rockauto.com . You could wire it for the newer sender if you don't care whether or not the fuel pump continues to run if you're in a crash and the motor shuts off, otherwise, I'd get the right sender, :wink: 8)
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Re: 2.8L to 350TBI Wiring Questions

Postby jester8798 » Tue Sep 12, 2017 1:05 pm

Thanks Rick, I wasn't sure.

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-Michael-
1987 GMC Jimmy 4x4 2.8L to 350TBI
My build thread: viewtopic.php?f=28&t=38158
2015 Chevrolet Silverado
jester8798
My hoist hit me in the head!
 
Posts: 275
Joined: Thu Jun 13, 2013 10:25 am
Location: Lansing, MI


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