My 5.3L into an 85 GMC swb 2wd swap

[aussie]

wouldnt going 3.42 take off hardER, but make less MPG?

[glock35ipsc]

Yes, and no.

With the 2.73's right now, the engine is only turning about 1700 rpm at 75 mph. That's way too low, and the engine is lugging because of it. The 3.42's will have the engine turning about 2250 at 75, right where it should be for optimum performance and economy.

And yes, it will scoot off the line much better.

[lechez71]

how did you fit the fuel pump in the tank? and what fuel pump did you use? im almost done with the 5.3L swap in my 82 c10 but i have no idea how to fit the fuel pump. any help is appricated.

[glock35ipsc]

You will need to swap the sending units to the 87 models. The 87's had TBI and used in-tank pumps. The sending unit part numbers are:

* Dorman p/n 692027 for the driver side, $94 at rockauto.com
* Dorman p/n 692044 for the passenger side, $101 at rockauto.com

I used ACDelco fuel pumps:

* AC Delco EP381 in-tank pumps. $69 at getgmparts.com

And a high pressure tank switch valve:

* Pollak high psi tank selector valve. $83 at JC Whitney, p/n ZX812705U

And be sure to use fuel injection hose, not regular fuel hose. Also use good fuel injection clamps, not the typical worm gear clamps.

Since everything will be out, you might as well swap to the 87 style tanks too. They have a large "bowl" that the pumps sit down in to. They keep the pump surrounded with fuel when the fuel level is low, and/or when you brake hard. You can use the 86 and older tanks, but you will kill the engine when braking hard when the fuel level is around 1/4 tanks or less. I had this problem with the TBI engine and the original 85 tanks, so I swapped to the 87 tanks when I did the 5.3l. I've ran then down to having less than 2 gallons left and haven't had a problem.

[GasGuzzler]

I thought they did not have baffles?

[glock35ipsc]

Baffle, bowl, what ever you want to call them. They are in there.

[GasGuzzler]

Oh, OK.

[thArf]

hows this comin

looks good tho

[bjetinsp]

I just want to say thanks for all of the documentation on your engine swap. I just found this forum in my quest to find info for my engine swap. I am shopping for a 5.3 myself and want to keep my 700r4 in place because I have a 1987 4X4 and don't want to do a lot of work moving the drive train around. I am very impressed with mileage you getting now. (just what I am looking for).

[lechez71]

You will need to swap the sending units to the 87 models. The 87's had TBI and used in-tank pumps. The sending unit part numbers are:

* Dorman p/n 692027 for the driver side, $94 at rockauto.com
* Dorman p/n 692044 for the passenger side, $101 at rockauto.com

I used ACDelco fuel pumps:

* AC Delco EP381 in-tank pumps. $69 at getgmparts.com

And a high pressure tank switch valve:

* Pollak high psi tank selector valve. $83 at JC Whitney, p/n ZX812705U

And be sure to use fuel injection hose, not regular fuel hose. Also use good fuel injection clamps, not the typical worm gear clamps.

Since everything will be out, you might as well swap to the 87 style tanks too. They have a large "bowl" that the pumps sit down in to. They keep the pump surrounded with fuel when the fuel level is low, and/or when you brake hard. You can use the 86 and older tanks, but you will kill the engine when braking hard when the fuel level is around 1/4 tanks or less. I had this problem with the TBI engine and the original 85 tanks, so I swapped to the 87 tanks when I did the 5.3l. I've ran then down to having less than 2 gallons left and haven't had a problem.

was the AC Delco EP381 in-tank pumps a direct replacement or did you have to modify the sending unit? also what is the pump rated because i cant find any info anywhere? thanks