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Old 12-08-2017, 11:48 AM   #1
Marty68
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5.3 to 91 gmc 5 spd

i have a disassembled 91 gmc. 5.3 5 spd. what basics do I need to put a 5.3 in front of it? clutch wise? will truck pan clear.
swap what in tank fuel pump
re do stock harness
what clutch pieces?
will dirty dingo plates work? stock rad? electric Taurus fans.
do dbc.

asking for a friend
is there a build thread I should read?
thanks guys.
Marty
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Old 12-10-2017, 02:57 PM   #2
robertsjm711
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Re: 5.3 to 91 gmc 5 spd

I assume you meant "91 GMC 5.7 5 speed", and if so... I have this from another similar post on another forum.

I have a 5.3 and am planning on using a Muncie M20, I think the principle is the same. The devil is in the details.

From what I have read you need:

-Fly wheel from a 4.8 or 6.0
https://www.summitracing.com/parts/luk-lfw387

-Clutch kit for your trans (I need a 10 spline, yours may be different)
https://www.summitracing.com/parts/luk-04-049

-Something to do the clutching (I am using hydraulic but I cant imagine mechanical being bad)
https://www.summitracing.com/parts/hre-82870

-Pilot bearing for LS
https://www.summitracing.com/parts/ADO-CT1082

-Shifter (obvious, I know, but mine was a pain- Thanks Hurst)

-Bell housing: This may be tricky - or not. I am using a 6263756 truck housing. The distance from the older trans are .4"(?) further from the engine that the LS - something about the crank shaft flange. It depends on which crank you have will determine if you need to make adjustments. They make flywheels that are thicker, but they are $$$ (for me, at least).
I also had to use an adapter ring to mate the trans to the housing (http://dennymac.com/muncie-bell-housing-adapter-ring)

- cross member mount: I made one

- VSS for the 5.3 computer
https://www.summitracing.com/parts/rpc-250-4153

Resources I use:

https://ls1tech.com/forums/conversio...-ls-motor.html

https://www.youtube.com/watch?v=RCGl5HbrUeE

I am using a Walbro external pump - not sure if the TBI has enough flow/pressure. I bet there are aftermarket kits - or maybe a stock one from a LS vehicle. There are returnless and two line fuel rails on the 5.3s

Radiator should be fine

I made my own motor mounts, but your application may have more options for pre-made

Use harness & computer from the 5.3, I used https://www.facebook.com/pg/LT1-Swap...70183759682543 as a guide. I will also use them for my computer reflash until I can get it to a dyno shop.

Can't say about the pan. There are different ones depending on your 5.3, I have the truck one and it is wicked deep in the rear.

I bet the fan will work, I don't think the 5.3 will make more heat than the 5.3.

There are the gauges that may need researched - not sure if they will line up. And OBD2 port, but those are cheap.

EDIT: To be clear, I am still in the installation & parts finding phase and have not tested all of this.
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Old 12-11-2017, 09:50 AM   #3
95 S_Trucker
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Re: 5.3 to 91 gmc 5 spd

Are you using a return or returnless fuel system?

If you are using a return style fuel system, you can use a pump for a 96/97 and it will swap into your current sending unit.
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