The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 10-25-2016, 12:58 PM   #1
cottonme173
Registered User
 
cottonme173's Avatar
 
Join Date: Nov 2013
Location: Sherwod, Or
Posts: 77
Quadrajet or Holly 650

This is on a '77 GMC C2500. Stock 4 speed, 4.11 Gear. I am not racing, just running on the street.

SO, initially I am having issues at full throttle. When running I can get trough second and third, but when I go into fourth and hit the gas my truck stutters and fails to speed up. If I gently push the gas it seems to keep up. Not that I floor it a lot, but I should be able to punch it.

I know very little about the Qjet's so I am starting very low there.

I am going to pull the truck in for the winter and go through both gas tanks, replace lines, replace the mechanical fuel pump, so this MAY actually solve my issue. I have the option of getting and rebuilding a Holly 650 to put on the stock intake. Will this even be worth it? Will there be a performance (MPG?) increase doing this?

I hope there are not a hundred other threads on this ( I tried searching and didn't find any).

I would love your input on this!
cottonme173 is offline   Reply With Quote
Old 10-25-2016, 01:01 PM   #2
meatwagon83
Registered User
 
meatwagon83's Avatar
 
Join Date: Dec 2012
Location: Preble county ohio
Posts: 1,914
Re: Quadrajet or Holly 650

On a stockish engine you can't go wrong with a quadrajet! Get yourself a book and rebuild it right, I've had holley carbs and edelbrock carbs on my truck and I keep coming back to the quadrajet, decent power and the best milage this side of fuel injection
__________________
"DON'T TOUCH THE TRIM!!"-Early Kyler
meatwagon83 is offline   Reply With Quote
Old 10-25-2016, 01:35 PM   #3
cottonme173
Registered User
 
cottonme173's Avatar
 
Join Date: Nov 2013
Location: Sherwod, Or
Posts: 77
Re: Quadrajet or Holly 650

Thank's for the input! When I first got the truck a few years ago I had a tune up done, but I was only getting a little over 6mpg!! I think I have a delivery issue though. That's why I am going through and replacing everything. Not sure what MPG I should expect with the 454, but that seemed low. I will find a rebuild kit for the Qjet and stick with that if that is the best thing for now.
cottonme173 is offline   Reply With Quote
Old 10-25-2016, 02:58 PM   #4
cottonme173
Registered User
 
cottonme173's Avatar
 
Join Date: Nov 2013
Location: Sherwod, Or
Posts: 77
Re: Quadrajet or Holly 650

Upon research......I guess that's on the high side of what I should expect....SMH...

Anyone need a 454....
cottonme173 is offline   Reply With Quote
Old 10-25-2016, 04:31 PM   #5
meatwagon83
Registered User
 
meatwagon83's Avatar
 
Join Date: Dec 2012
Location: Preble county ohio
Posts: 1,914
Re: Quadrajet or Holly 650

I rebuilt mine with a small bump in compression, a small cam (comp he260) headers and a performer intake, with a fresh quadrajet, 10 around town, 12 on the open road, no overdrive, 3.73 gears, and that is in a crew cab dually, when I got the truck it was stock with an edelbrock 750 on it and it got 9
__________________
"DON'T TOUCH THE TRIM!!"-Early Kyler
meatwagon83 is offline   Reply With Quote
Old 10-26-2016, 11:18 AM   #6
truckin 79
Registered User
 
Join Date: Jun 2014
Location: CO
Posts: 727
Re: Quadrajet or Holly 650

I would go with the Holley if it were mine. The holley is easier to adjust float level and idle mixture screws on the side. The q-jet has idle screws in the front and if you get junk in carb you have to take half the carb apart to clear. I have a q-jet on Trans Am and Truck, it took me a lot of tinkering to get the q-jet on TA to start with just a flick of the key. The q-jet on truck is fighting me though and needs some more fine tuning, I just rebuilt q-jet so trying to stick with it for now. I might switch to a Holley on truck with vacuum secondaries and it should get about the same gas mileage as q-jet. In the end both carbs are good but q-jets a bit more fickle IMO.
__________________
79 Chevy 2wd BIG10 350 TH400
truckin 79 is offline   Reply With Quote
Old 10-26-2016, 11:49 AM   #7
geezer#99
Registered User
 
geezer#99's Avatar
 
Join Date: Aug 2009
Location: Bowser
Posts: 13,494
Re: Quadrajet or Holly 650

Quote:
Originally Posted by truckin 79 View Post
I would go with the Holley if it were mine. The holley is easier to adjust float level and idle mixture screws on the side. The q-jet has idle screws in the front and if you get junk in carb you have to take half the carb apart to clear. I have a q-jet on Trans Am and Truck, it took me a lot of tinkering to get the q-jet on TA to start with just a flick of the key. The q-jet on truck is fighting me though and needs some more fine tuning, I just rebuilt q-jet so trying to stick with it for now. I might switch to a Holley on truck with vacuum secondaries and it should get about the same gas mileage as q-jet. In the end both carbs are good but q-jets a bit more fickle IMO.
A lot of tuning and lack of mileage is related to a slow timing curve. Especially at elevation.
What's your timing like truckin?
geezer#99 is online now   Reply With Quote
Reply

Bookmarks

Tags
454, c2500, holly, quadrajet

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 01:42 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com