Full Size K5 (1969-1991) GMT415 (1992-1994) Tech Discuss any and all full size K5 general tech topics here.

1991 K5 FI to Carb Conversion

  #1  
Old 10-18-2009, 06:26 PM
Thread Starter
Join Date: Oct 2009
Posts: 6
K5joker is on a distinguished road
Default 1991 K5 FI to Carb Conversion

Ok...

Having some issues with the way the truck has been running and after having a few of my buddies over at GM take a look they all advised converting mine to a carb motor and ditching the computer.

My truck is a 1991 K5 Blazer w/5.7L injected motor. (obviously early stage of fuel injection as it appears someone simply took a carb and installed computer driven jets into it). It has an automatic transmission installed (fyi just in case there are any issues with changing to carb related to the tranny).

I understand i need to purchase the following:

Carb Manifold
Carb 650-750 (recommended by others)
Kick Down Plate / Springs / Linkages
HEI distributor
Fuel Pressure Regulator??

I've had trouble finding sites or people familiar enough to tell me with certainty as to what parts I need to be looking for specifically.

I'm not too worried about fuel economy as she currently gets about 8-12 MPG at this point anyhow.

The motor currently has about 180K on it and still holds compression on all cylinders and seems to have really been babied so I will likely hold off on a total rebuild til later.

Transmission is new-ish... has about 20-30K on it based on paperwork I have from former owner. Transfer case is brand new.

Back to the carb question....

I'll take any advice i can get here on this little project.

I have no problem at all with the mechanical installation and setup aspect so long as I have the right pieces in place... heads up on possible heater hose connections would be useful as well as what little i have found online did mention hose connection points as a problem.

I'm hoping there are no tranny issues in doing this as well.

Thanks again! -Andy
 
  #2  
Old 10-18-2009, 06:36 PM
swartlkk's Avatar
Administrator
Join Date: May 2005
Location: Waterloo, NY
Posts: 40,792
swartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond repute
Default

I am going the opposite direction as you with my '74. I'll be dropping in a '90 Suburban 5.7L TBI motor into it.

ThirdGen.org is a great resource for TBI information and that includes the very swap you are considering:
Swapping from EFI to a Carb in a Thirdgen - this article will hit the high points of what is necessary.

You've basically gotten it correct. The only other thing that you may find that you have to do is find another way to control the lock up of the transmission torque converter.

Here is another good article from ThirdGen.org:
How to Choose the Proper Carburetor and Fuel Pump
 
  #3  
Old 10-18-2009, 11:03 PM
abig84's Avatar
BF Veteran
Join Date: Aug 2009
Location: munster indiana
Posts: 3,426
abig84 will become famous soon enoughabig84 will become famous soon enough
Default

sounds like you listed all you need. you can ditch the fuel pump all together and run a mechanical fuel pump on the block if your cam allows for it. i did this swap on a 85 s10 blazer. but this was 8 years ago.
 
  #4  
Old 10-27-2009, 01:49 PM
Thread Starter
Join Date: Oct 2009
Posts: 6
K5joker is on a distinguished road
Default Torque Converter Lockup

I've had a few local mechanics indicate (as well as one of you above here) warn me about tc lockup control when I make this changeover. I've found very little that is helpful to this question. Obviously my other project of converting to a manual tranny will render this a "non-problem" issue but for the first 3-6 months I'll be driving it with the automatic still. I've been climbing around and am not sure what currently controls this. Is it a physical linkage or just a cable that drops from the throttle cable bracket down to the transmission that I just need to get re-connected correctly when I'm finished? Haven't had much time lately to do much but was curious. -Andy
 
  #5  
Old 10-27-2009, 02:24 PM
swartlkk's Avatar
Administrator
Join Date: May 2005
Location: Waterloo, NY
Posts: 40,792
swartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond reputeswartlkk has a reputation beyond repute
Default

Torque converter lockup is controlled electronically.

Have a read through this:
http://www.smokemup.com/tech/700r4.php

Also take a stroll through BowtieOverdrives.com.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Brandon Smith
General Chat
1
12-22-2013 12:33 PM
Bobcat13
Engine & Transmission
9
11-10-2013 06:03 PM
Williamsb7181
1st Gen S-series (1983-1994) Tech
1
05-09-2013 09:49 PM
88cougar
Engine & Transmission
0
09-10-2010 04:11 PM
in2classx
1st Gen S-series (1983-1994) Tech
3
09-04-2008 10:56 AM


Thread Tools
Search this Thread
Quick Reply: 1991 K5 FI to Carb Conversion


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.