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#1 |
Registered User
Join Date: May 2000
Location: Houston,Texas
Posts: 123
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ATTN Crewcab owners
Hey guys
I've got my new project crewcab longbed. It has a 454 and t400 trans in it, and as you all know the gas prices are on the rise. Thinking about putting a complete 350 tbi and 700r4 out of an 89 silverado in my truck. Whatcha think. any gas mileage increase or decrease? Will it even move this big beast? Would the trans hold up? Should I just leave the big boy in there? I won't do any kind of heavy hauling just my 21FT boat. Advice? ![]() |
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#2 |
Robert Olson Transport
![]() Join Date: Oct 2002
Location: recent transplant to NC USA
Posts: 20,287
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i dunno about gas mileage but i haul a 20 foot boat with a four cylinder ranger all the time all over the east coast
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Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!! |
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#3 |
Happy to be here
![]() Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,023
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If you are going to covert it to SBC, don't go with the 89 motor. I can't remember the exact hp/tq numbers on it, but they aren't that great. I would find a 96-99 Vortec motor instead. BIG difference in power and torque.
What gears do you have in the rear? That will make a difference too. If it has 4.10 gears, and a T400, you might save some hassle by going to 3.73's and an OD trans. What kinda mpg are you getting now, about 10?
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Follow me on Facebook and Instagram @N2trux.com Articles- "Jake" the 84 to 74 crewcab "Elwood" the77_Remix 85 GMC Sierra "Scarlett" "Refining Sierra" |
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#4 | |
www.73-87chevytrucks.com
![]() Join Date: Dec 1999
Location: Birmingham, AL
Posts: 6,935
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Re: ATTN Crewcab owners
Quote:
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Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com |
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#5 |
Registered User
Join Date: May 2000
Location: Houston,Texas
Posts: 123
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I'm getting about 9 mpg. I've got 3.73's in it. Thought about putting a 4L80 with a controller in it, but came across this wrecked 89 truck cheap but haven't bought it yet. thanks for the replies.
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#6 |
Happy to be here
![]() Join Date: Mar 2000
Location: Cypress, TX
Posts: 39,023
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Poonman86
I have had a few of the SBC TBI trucks ( 88, 91,93,95,) and was not impressed with the power, or mileage. Stay with the BBC, and go for the OD trans. That should give you one or two better mpg. Also, the 88-89 700R4 weren't that great. I went through a couple in my 88. Of course when I sold it, it had over 300k on it... ![]() |
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#7 |
yeller
Join Date: Oct 2001
Location: Twin Cities
Posts: 13,826
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I say stick with the BB and 400 trans...but get a Gear Vendors OD unit...you will then have 6 speeds as opposed to a 700r4 which only has 4. It just bolts on the tailshaft of your trans and installation is pretty straight forward. You will need to shorten your existing driveshaft as well. Also, depending on your current tire size and their condition (tread wise), you could get a taller diameter tire...that will reduce your freeway RPM's a little and help on gas.
-Jeff |
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#8 |
Registered User
Join Date: Jun 2003
Location: turon ks
Posts: 120
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Gas miledge
I have a 75 crew cab dually, with 400sbc, 400 turbo, 4:10 rear gears, and 8.75- 16.5 tires. I haul 6000lbs daily average of scrap iron in the bed, I get 12 mpg. I'm getting ready to build my 402 BBC to put in it.
Good luck Tibbar |
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