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  1. #1
    Jr. Apprentice Busted Knuckles's Avatar
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    Question 7.4L Conv. - 96 Tahoe

    Hey folks , I know this has been hashed out till it's dead (or almost) . I did do a search but came up empty . So here it goes again .

    My 96 Tahoe has 190k. on it , it uses no oil , runs at 45-50psi.oil pressure at 65-70mph. runs great . But when it's about -5/-10*f. and I go to start it it has pretty noticeable pistop slap for about 2-3 minutes . And in my mind if they are slapping then they're wearing and causing friction . My mileage used to be great but has dropped alot over the last year I'll blame some mpg. loss on my tires .
    I've given up on a Diesel Conversion .
    I'd like to do a 7.4L / 5spd. Manual . I've done alot of conversions but on Classic Cars . So the Tahoe will be familiar territory so to speak .
    Who else has attempted this ? I'd like to stay away from the 4l80E not only for the measley Torque Rating but also the computer . I figured a 5 spd.would be easier . I know about the drive shaft issues,cross members ( was told to get one from a k2500-3500 for the solid mount rear torsion bar set-up) .
    Also I may fore-go EFI . I'd like to cam it up a bit , go with an Edlebrock Intake and Rotchester Spread Bore ( I'll need a fuel pressure regulator for sure ),headers and open up the exhaust .eventually some roller rockers ,MSD 6AL .
    Buy then I'm sure it will put out more than 360ft.lbs of torque .

    How's this sound ?

    Should I instead snatch an ECM/MAF for the 7.4 and what's the injector (Spider)upgrade that changes the type of injection (Batch Fire to SFI ?)

    Steve
    Peoples Suspicions are only aroused by our actions !

  2. #2
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    murdog94's Avatar
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    I am actually a HUGE fan of EFI, and with the cam, and everything else you want to do the 7.4L is basically a direct bolt in, as long as you get the PCM for the 7.4L and the 5spd as well. honestly if you can find a wrecked etc donor truck that will have everything you will need to make it work, and any little odds and ends that always seem to get missed.
    Also with the 7.4L and EFI you will be able to pull 1-2 more MPG over a carb set up. and the vortecwith EFI is reliable as well.
    Mike

    Currently

    1997 Chevy S-10 Blazer 4X4 with 330K miles and counting (Hunting rig).

    2009 Saturn Aura XE (wifes car)

    2011 F-150 Crew 4X4

    "Hold it to the floor till you see God.... Then Brake!!!!"

  3. #3

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    Murdog, do you know how a 5spd would play into an EFI setup? I'm thinking the computer needs to be from a truck that had a 5spd in it previously so it doesn't get confused from the lack of input from the auto transmission. You're also going to need the complete wiring harness, as I think sensors are in different spots.
    Christopher

    1991 Chevy Suburban 1/2 ton 2WD w/ chevy SBC 350-3/4 ton drivetrain upgrade w/4.10 gears 200K miles
    2005 Saturn ION-2 Stock 265K miles
    1982 Bronco, 1993 Bronco (sold), 1971 M35A2 Deuce and a Half



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  4. #4
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    murdog94's Avatar
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    That is why i said donor.. I completely get the wiring harness for the tranny side (different junction block and easy switch) and yes the PCM needs to be from a 5spd and or you can simply buy a new one for a 5spd. I forgot to add all of this thanks Crawdaddy... But with the mounts for a 5spd, and motor mounts for a 7.4L it is basically a direct bolt in process.. You will need i believe the larger radiator for a 454 but im not 100% on that one since most that i have seen done already had a larger rad for pulling installed in them .
    And it would be wise to get the correct wiring harness or else a few of the sensors for the front of the motor you may need a bit more wire. But the one for the distributor, and the TB are the same.

  5. #5

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    why do you give up on diesel conversion ?
    its easyer and WAy better then a 454 ( 7.4l )

    1996 Suburban K3500 SLT DUALLY
    1988 Camaro RS 383 stroker LT1
    1992 32' Aero-tek Race Boat, 600 CI BBC
    WE CAN STICK A DIESEL IN ANYTHING
    SPECIALIZED IN CUSTOM CONVERSIONS OF ANY KIND
    Scott:glasses:

  6. #6
    Jr. Apprentice Busted Knuckles's Avatar
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    Thanks folks !
    I figured I'd need the main engine harness and new about the PCM deal . I had one guy interested in a partial trade for my 5.7/4l60 . He tried to tell me he had ran 7.4's on a 5.7 PCM . Maybe it IS possible but I'm sure it would more than likely run like crap . It may be awhile , We're stocking up on dry foods, ammo . Got a bad feeling the Defecation is set to hit the Rotary Occilator sooner than later . Yeah, go ahead and call me nuts ! But things here are even getting more grim by the week . The A$$ Holes in Washington didn't get the message last November . Now they're cutting Social Security Medicare and Medicaid (Is Disability next,how about Veterans Disability ?) Those are our sole source of income . I've never really hunted but there is plenty of game here and I think I may still be able to get a garden up and running this season .
    As far as the diesel conversion , we had some of the cheapest gas prices but over night it literally went up .65c per gal. now it's $1.50 over what it was 6-9 months ago , Diesel was $2.35 now it's $3.25 . But with the crap over there in Middle East and Isreal the news said tonight it's going to surge . That means food and everything else coming in by truck will be right beside the gas . If you have the "means" keep an open mind . If you can hunt do it and if you have the space and time get a garden going .
    This is no joke , and our Government is Clueless or in Denial and Lieing through their teeth that everything is warm and fuzzy .
    So the truck is gonna HAVE to hold for awhile . ^%*%^* !!!!!!!!!!!!!!!!!!!!!!!!

    ---------- Post added at 12:20 AM ---------- Previous post was at 12:02 AM ----------

    Quote Originally Posted by DAREDEVIL View Post
    why do you give up on diesel conversion ?
    its easyer and WAy better then a 454 ( 7.4l )
    Scott I'm open to new Ideas after I saw your Diesel Specialty . What kind of mileage can I expect over a 7.4L ? What engine ? I hear the GM Diesels can develop crackes in the Mains
    Webbing due to GM trying to lighten the engines . How common is that ?
    That conversion seems like it would be much harder with wiring . If using a GM Diesel I'd need the PCM but would the main engine/tranny harness plug into the main wiring block down on the firewall ? Is the mileage gains (if any) be worth the trouble of the conversion ? With the price of diesel it would be over $100.00 to fill my tank .
    Hell, I'm gonna buy a couple Mules !
    Last edited by Busted Knuckles; 02-17-2011 at 12:23 AM.

  7. #7

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    Scott I'm open to new Ideas after I saw your Diesel Specialty . What kind of mileage can I expect over a 7.4L ? What engine ? I hear the GM Diesels can develop crackes in the Mains
    Webbing due to GM trying to lighten the engines . How common is that ?
    That conversion seems like it would be much harder with wiring . If using a GM Diesel I'd need the PCM but would the main engine/tranny harness plug into the main wiring block down on the firewall ? Is the mileage gains (if any) be worth the trouble of the conversion ? With the price of diesel it would be over $100.00 to fill my tank .
    Hell, I'm gonna buy a couple Mules ![/QUOTE]

    Knuckels, about the cracked blocks..that was a loooong time ago. + we use navy engines. no electronic BS ( so nothing to worry about with anything elecctric going wrong ) , the blocks are a better casting then the standard GM and the internals as well...marine injectors, we install a intercooler and beef it up a notch.
    MILAGE....i say 3 times as much as a 7.4 ( 454 ) if not more, (100 bucks of gas does not fill it up either) ! Better tourge and better power at the right spot.
    1 year warranty and the engines are rebuild ..( so basicly 0 hours / miles on them ), we give costumers the option to a bigger turbo and some other upgrades, also a POWER PACKAGE or a diesel saver !!! EVEN THE POWER PACKAGE GETS WAY BETTER MILSAGE THEN A GASSER + with a few mods you can even run VEGGIE OIL...LOL ( not kidding you either, have a frined that runs it and picks it up from restaurants for free " old grease " ...he filters it in a home made filter and stores it in some 55 gallon drums ) . crazy..but very cheap and runs very good actually, has a little less power HP wise but still pulls and runs fine.
    We offer the swap for $ 6K + no extras included is a lot tho. JUST LOOK HERE ..... >>>http://www.gmtruckclub.com/forum/sho...!!!!-LOOK-HERE

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