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| | | | Joined: Feb 2008 Posts: 207 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2008 Posts: 207 | does anybody have an estimate on what kind of gas mileage my 72 GMC 7500 6X6 wrecker would get pulling a 28 foot semi trailer. it has the 401M 10 speed overdrive transmission and 7.10 axle ratio. also has a edlbrock 600 cfm carb.
Last edited by 47chevy6400; 06/07/2008 3:33 AM.
| | | | | Joined: Apr 2003 Posts: 942 'Bolter | | 'Bolter Joined: Apr 2003 Posts: 942 | I believe my '62 GMC 6500 with a 478 V-6 got about 7 or 8. The overdrive you have will help, but if you can get 8 that would be pretty good in my opinion.
Bill
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
| | | | | Joined: Jan 2008 Posts: 4,961 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,961 | I think 7 or 8 is wishful thinking. 5 is more realistic. If the 28 footer is a dry box 13'6" high expect about 4. Those old gas burners weren't very fuel efficient. I ran them until the late 60's. I run all diesels now. | | | | | Joined: Feb 2008 Posts: 207 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2008 Posts: 207 | | | | | | Joined: Jul 2006 Posts: 707 Shop Shark | | Shop Shark Joined: Jul 2006 Posts: 707 | 3.5 - 4 is what I'd expect. That's what an old glass truck I once had got with a 427.
1951 3800 Be the change you want to see. -hotshoe
| | | | | Joined: Dec 2006 Posts: 720 'Bolter | | 'Bolter Joined: Dec 2006 Posts: 720 | A thought for ya, I had a '65 3/4-ton with a 327, TH350, & 5.30ish gears out back. When I got it the intake was all stock for that motor and it got horrible milage, somewhere around 5 or so. However, I broke down and bought a 650CFM 2-bbl Holley Pro-Jection TBI system and a Edelbrock performer intake. Between that, shorty headers with dual turbo mufflers & a swapped in HEI ignition, I went up to approx 10-15 MPG and could tweak it to run cleaner than a new car, plus had the ability to adjust on the fly (I mounted the brain in the glove-box. Before she died on me (head gasket leak, siezed piston, busted rod, oh darn,...) I was pulling a trailer and fully loaded bed and there was no real difference in fuel consumption.
I cant say what sort of performance gain YOU would get, but it's a thought.
I know it's heresy, puttin something so new fangled & confusing to work on on an old bolt, but then I'm one to be controversial. :P
However, if you're lookin to get the most bang for your buck,... It's an idea anyway.
1956 GMC 370 dump " 'Tater "1970 VW Volksrod "the Black Bomber" 2007 Chevy Avalanche 2020 Jeep Cherokee Trailhawk, 2005 Harley Davidson FLHTCUI I dig all cars, old and new, whether they were hammered out of American iron, German steel, or Japanese tin cans. Being unable to appreciate them all is missing out on a world of great things.
But thats just MY opinion! :P
| | | | | Joined: Feb 2008 Posts: 207 Wrench Fetcher | | Wrench Fetcher Joined: Feb 2008 Posts: 207 | i haven't seen any intake manifolds for the V6 but i do have rebuilt 427 tall deck that i could put in and run fuel injection with | | |
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