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91 K5 mods.

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by MR4WD, Jan 12, 2003.

  1. MR4WD

    MR4WD 1/2 ton status

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    Hey guys, I'll let this be my first post...

    I just picked up a 91 blazer with a EFI 350/465/241?? and 10 bolts. (Everything's bone stock) I've had it for 2 days now and I haven't torn into the diffs to see what gears I've got... Any ideas?

    What sort of mods can you do to these engines without the computer having a cow? What brand of headers work best for these EFI trucks? All I'd like to do for now is intake, cam and headers. How will the computer react to these?

    Later on I plan on a 6" lift and 35's. I'll probably upgrade to a 3/4 ton 10 bolt and a 14 bolt with 3.73's or there abouts. What has to be done to the rear driveshaft in order for a 6" lift and 14 bolt to work (outside of the 1310-1350 problem)??

    I plan on using this truck as an economical daily driver, that will see very little off road. Sacrelige!

    My other truck's got a 496/fully manual 400/32 spline np205 with 5.13's and detroits in the Dana 60 and 14 bolt. 44" boggers on 15x14 bead locks... So, I'm not new to the game, just inexperienced with EFI/TBI setups and how modification friendly (or not) they are...

    Thanks for your help guys, Chad. /forums/images/graemlins/thumb.gif
     
  2. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

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    As long as you keep the engine mods tame, the computer won't have a problem.

    As for gearing, I'm running 33's right now with 3.73 and it's a dawg on the hills. With the 700R4, you could probably step up to 4.56 gears. And keep the Grade 12 bolts away from the K5, they don't like them. /forums/images/graemlins/rotfl.gif
     
  3. bablazer73

    bablazer73 1/2 ton status

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    First off, let me say WELCOME to the best damn blazer site their is! People like to know who you are, please fill out your profile. Check out the site, see what it can offer. Tons of info, other people's ideas. what works, what doesn't! who to buy from and well,, who not! Membership fee of 25.00 has many more benifits, including discounts at various venders. one puchase can give enough discount to pay for your membership. Also for future reference, If you are looking for specific info, try using the sites search engine. We get tired of reading repeats of posts that have been up before. now that thats out of the way.
    your truck most likely has 3.08 or maybe 3.42 gears in it now. Run a search for R.P.O. codes. you can figure out that way.
    There are plenty of computer friendly performance parts out there. intakes, headers, ignition systems. Just check out summit or jegs.
    There are several options on 6" lift. some will depend on what you will actually do with your truck. on road, on off, or hard core off roading. Check out shackle flips, Check out the off road design site. (members get discounts)
    If you are gonna run 35's I would consider 4.56 gears. 3/4 ton axels are great, BUT 1 ton is better yet! dana 60/14 bolt.
    you want driveshafts?? check this shop out high angle driveline . jesse, the owner is also on this site.
    All the info you will ever need is right here, check out all the forums. use the search engine and see what this world can offer!
    oh, did I mention membership?? /forums/images/graemlins/k5.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/burb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/truck.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  4. Derf00

    Derf00 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    I plan on using this truck as an economical daily driver, that will see very little off road. Sacrelige!


    [/ QUOTE ]

    If this is the case, why bother upgrading the axles? The engine mods will work fine without drastically efffecting the computer.
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Besides offering better city mileage.

    Diff codes are in the glove box, all starting with "G" or at least the second digit "G" if they are 4 digit codes. You can find the breakdown of RPO's (thats what those are called) either by doing a search here or off of google if you like. I know one off the top of my head, G80=gov-lock. If you pull the diff cover and find something other than a gov-lock, let us know. (supposedly some had a real eaton posi, haven't seen one in a truck 10 bolt myself)
     
  6. Z3PR

    Z3PR Banned

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    </font><blockquote><font class="small">In reply to:</font><hr />
    If this is the case, why bother upgrading the axles?

    [/ QUOTE ] You can usely find a set of 3/4 Ton axles with the more desierable gears for cheaper then doing a gear swap in the 10 bolt axles, and have the added strength of the 14 Bolt FF. !!!!! And it's pretty easy to hang some new axles while you've got it apart doing a suspension lift.
     
  7. Derf00

    Derf00 1/2 ton status

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    </font><blockquote><font class="small">In reply to:</font><hr />
    I plan on using this truck as an economical daily driver, that will see very little off road. Sacrelige!


    [/ QUOTE ]

    If the gears are an issue I don't disagree, but hauling a 14B around won't help economy.
     
  8. Stickseler

    Stickseler 3/4 ton status

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    Being reliable is a major goal for mine. I like to hit the back wood trails that don't see much use. So The mods I'd recomened would be: 3/4 Ton axles (cheaper then 1 Ton, but 1 Ton is better) and either a 4" or 6" suspension lift, and 33" to 36" tires. Now I don't know how you feel about trimming fenders, so I'll leave that one alone. That'll get ya out in the woods. /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif
     
  9. imiceman44

    imiceman44 1 ton status

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    Hey guys if you noticed he has another with 14b d60 and 44" tires so this one is DD and 1ton running gear is overkill.
    I don't think he wants a replica of his other rig.
    Up to 35" I would keep the 12b/d44 especially if you are not going to abuse it since you have one for abuse.
    /forums/images/graemlins/thumb.gif
     
  10. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    91 would have 10/10 not D44/12...

    Rene
     
  11. imiceman44

    imiceman44 1 ton status

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    Sorry I thought I read that he had those axles, but still the same, marginal difference. /forums/images/graemlins/thumb.gif
     
  12. MR4WD

    MR4WD 1/2 ton status

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    Hey guys, thanks for the input. I'll check into the RPO's and let you know how I made out. As was pointed out, I've already got another machine that I beat up so I'd like to keep this one reliable. It was -35c last night and the truck started up and built heat without a problem.... It'll do 100 miles on 1/3 a tank of gas, which in my opinion is next to a pontiac sprint.

    Since most people reguard 35's as the limit for 10 bolts, and I've taken a significant number of them out of the population I'd like to change them. I don't feel comfortable riding around with them supporting my truck at all. Hell, I even broke 3 or 4 14 bolt shafts this summer with my real 4x4. The added 200 pounds or so I'll get when I replace the diffs with 3/4 10 bolt and 14 bolt is easily offset by the swept brake area (I'll do yet another disc conversion), bearing surface and strength of axles. That's the difference between a good set of bumpers and the stock chromeys. (this is an ex-government unit with an 8274 and ugly bumpers already)

    Anyways, I'd like to pull 300 or so horse out of the small block and I'm curious as to what sort of upgrades I can get into before the TBI has a fit. Seems to me rebuilding the engine's a pretty good idea. (balancing, blue printing and THEN getting into mods)

    Do people get 6" lift and 14 bolts under their trucks without retarded vibration? I had a look at the driveshaft, and it seems steep and short out of the factory.

    Thanks for the input guys and here's some video of my other 4x4.

    Got bumpsteer?
    http://www3.telus.net/public/mhepburn/bounce.wmv

    Got water?
    http://www3.telus.net/public/mhepburn/water.wmv

    This is mostly what I wheel. If there were rocks, I'd wheel those, but there isn't any for at least a 10 hour drive (and those you're not allowed to wheel)
    http://www3.telus.net/public/mhepburn/skeg1.wmv

    I wheeled all of this in places I was allowed. Off-road areas and utility company owned right-of-ways that have decade old tracks...
     
  13. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    YES YES YES!!!! /forums/images/graemlins/thumb.gif Videos are always welcome here!! Finally some fresh ones! Nice water crossing!
    Way cool truck! Longbed on 44's! /forums/images/graemlins/thumb.gif
     
  14. MR4WD

    MR4WD 1/2 ton status

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    Thanks bowtieblazer.... Anybody have any input reguarding rear driveline angles when using a 14 bolt and a 6" lift? Would it be best to go to a SYE for the 241, or can I run the stock shaft (with a 1350 joint in the back) and get no vibration? I'll end up doing a lot of highway with the truck, and hitting 75MPH is something I'd like to achieve without the truck falling apart.
     
  15. Thunder

    Thunder 3/4 ton status

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    Sounds like the guys have the axles covered so I'll talk about engine.
    These mods will get you pretty close to your goals of performance reliability and gasmilage.
    300 Hp is about max HP you can get out of the 1 11/16 " bore throttle body. You can go up to a 2" bore (454 theottle body) and build more power if you want.
    You will need to modify the throttle body to flow better with spacers, adjustable fuel press regulator, bigger/ flow mjatched injectors,ect, ect. The stock TB does not flow very well. And these mods are relitivly cheap for the performance boost you get.
    Go to:turbocity.com
    They have all the stuff needed to modify TBs to get the most out of them. I have been using their stuf for years and it works good ( i'm building up a buddys TBI up today)
    They also burn custom performance chips for your computer. Call them talk to their Tech people about what you want to do they will help you out.
    What I like about TBI is as you modify them you get both power and gasmilage My TBI 350 K5 gets 18 -20 MPG going down the freeway ay 70.
    Balancing and blueprinting your engine is the only way to go in my opinion. I wont rebuild an engine without balancing it. it only costs a little more ann the results are worth it.

    You can usually get away with a compression ratio up to around 9.5 to 1 with the stock chip in the computer. I think 9 to 1 is ideal

    Quite a few companys make cams that are compatable with your computer. Elgin' Edelbrock, Comp cams, ECT. Cams with durations up to 212 degrees and up to around .480" of lift will work with the stock chip and build plenty of torque.. Anything more than that and you will need a custom chip burned.
    Edelbrock makes a computer frendly TBI manifold/cam Kit that works good. Use the Performer series. The RPM is more of a top end cam.

    For headers I like the Edelbrock TES system. They build good troque and are very well made. I have had a set on my K5 over 3 years now and have had no problems/ leaks or rust.
    Top it off with a single 3" flowmaster exhaust.

    And if you want my advise about axles. If you aren't going to wheel it hard, And use it more for a daily driver. Just keep the 10 bolts and run 33" and small 2"-4" lift. You will loose a lot of miles per gallon with 14 ff and a 6" lift. Plus you wont have all the driveability problems of a axel swap and lift. And it will look very clean.


    Hope this helps.
     
  16. efilnikufecin

    efilnikufecin 1/2 ton status

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    i got a 91 blazer with the same set up you are thinking of running.i'm running a slip yoke style rear drive shaft with a cv joint and 1350's through out.i tried the stock shaft but got way to many vibes for my liking.here's a couple pics. [​IMG]

    [​IMG]
     
  17. bryguy00b

    bryguy00b 3/4 ton status

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    WOO HOOO!! those vdeos kick ass!! killer truck to!! /forums/images/graemlins/thumb.gif
     

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