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My 93' Chevy truck

Discussion in 'Chevy Trucks' started by DJ Contracting, Mar 7, 2005.

  1. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Well heres my problem my truck has no pulling power. This is what i have done in the past and i am wondering what my biggest power loss is? Outside of changing the engine back to a 350 what should i do? I no longer have the old engine. :cry:
    1. The truck came with 342 gears.
    2. 2003 Winter replaced the 350 engine with a 305 that i rebuilt w/a
    new torque style cam
    3. Removed the cat, converter (wondering if the lost of back pressure hurt
    low end torque)?
    4. 2004 Summer i replaced the 265/75/R16 with 285/75/R16 the truck
    originally came with 245/75/R16's
     
  2. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    gears or smaller tires
     
  3. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    I was thinking of 373 gears and 265 tires.
     
  4. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    How much do you pull, 2 or 4wd and what trans? Edit: never mind I assume 4wd

    Generally 373's and 265's are a pretty good combo.
     
  5. BigRedBarn

    BigRedBarn Senior Member
    Messages: 133

    Those 4 words nailed it.

    You've got much bigger tires compared to stock, and your differential gears have too low a ratio. I know those fixes are substantial, money-wise. You're proposing to change both, but just one or the other might do it.

    To me, if you stick with those bigger tires (I assume you have a reason for wanting them), then perhaps going to 4.10:1 gearing might do the trick. I guess you have to look at what your driving looks like. If you're not doing much or any highway driving (or aren't doing much highway driving w/o a load or trailer) then 4:10's might not be so bad gas-mileage-wise.

    When I ordered my 2003 Silverado and Trailblazer I got shorter gearing on both (4.10:1 on the pickup and 3.73:1 on the SUV). Based on what I use our vehicles for, this made the most sense. I don't really tow with the Trailblazer, but I wanted better acceleration in around-town driving as we do very little highway driving. I've driven my cousin's wife's 2002 Trailblazer and notice that it does seem a bit slower than ours (and it's broken in more, too), and mileage isn't much different (both Trailblazers aren't all that great). Plus too and also, the inline six in the Trailblazer is a 4-valve design, which needs to rev to get the most power, so shorter gearing is consistent with the engine configuration in the truck.

    I can't think of any other solutions for increasing torque and power for towing. I know you're correct to wonder if low-end torque is affected by lower exhaust back pressure. I'm not sure if it is or not. I do know that some people have concerns about valve damage with lower exhaust back pressure. To make the most of lower back pressure, I'm guessing that intake pressure drop should be reduced, too, if at all possible. Personally, I dislike those K&N-style engine-air filters as I don't believe they're good for an engine as they don't filter out fine particulate matter as effectively as a pleated-paper air filter. But, they're not evil, either, and if you take proper care of a K&N-style filter it shouldn't cause damage to an engine unless you're looking at putting on 200,000++ miles on the engine.

    Compared to the old 350, I would think the 305 would like a rev a bit more (if it's a shorter stroke design than the 350, which I'm not at all sure of, but I'm guessing it might be as I think they use the same bore...???), so maybe reprogramming the tranny to allow the engine to rev a bit more, or to down-shift sooner might be of some small help. Personally, I've never thought too, too much of the 350 or the 305, but maybe that's because they were brought out about the time when engines were screwed up from all sorts of new-fangled emissions controls back in the 70's. As far as Chevy small blocks go, I always liked the 283, like the one I had in the '67 Impala SS I once had which I had always wished had a big block. The SS really didn't do all that badly with the 283 as that sucker liked to rev.

    My last truck was a 125,000 mile '92 GMC with 350 & automatic and it was one tired truck. I know the engine had issues, but I think the tranny wasn't putting as much of the power to the pavement as it should've. That is, I think the tranny needed work more than the engine. Maybe a rebuilt tranny might be a good investment. Can anyone comment on when to rebuild the automatic in a 1993 GM pickup?

    One final comment, I've read where some people believe that an engine needs at least 10,000 miles to really break in and put out all the power it's capable of putting out. Personally, I've seen this to be especially true with some GM's I've owned in the past. I had one GM which seemed to have a really tight engine until it got a good 12-13,000 miles on it, and then it really had a lot of spunk after that. New engines can be pretty tight. I'm sure they vary substantially as engine tolerances vary a bit for the sake of keeping costs down to provide a reasonably-priced engine.


    That's all I can think to say here.
     
  6. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Well I got these tires BGF from my brother in-law at a good price, thinking it wouldn't affect the truck to much. Anyway i got prices for both putting on the original size tire @ 480.00, And I also got prices for replacing the axle gears $1050.00 for both parts and labor (4:10). I had the transmission rebuilt in 2000 and i have to correct myself, i rebuilt the engine in 2001. I will sell the BFG TA's.
     
  7. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    a grand fo both dosnt seem to steep. Setting up gears can be a PITA to do right. 342's are still pretty high for a truck BRB gave a very detailed post. :cool:

    How heavy are you towing?

    Do you have a trans with OD or just a 3 speed? I assume OD I cant remember if you could get a 1/2 ton without OD in 93???? If you have OD with those tires 410's really wouldnt be bad on the highway.
     
  8. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Yeah it's the overdrive and i'm pulling about 2800 - 3000 lbs
     
  9. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Well, the first problem is the smaller displacement. A 305 will never be a towing motor! It uses the same 3.48" stroke as the 350, with a much smaller bore. The TBI style heads are not well known for flow, though I would think for a torque-oriented motor they would be fine.

    I suggest regearing if you don't want to play with the motor. There should really be a cat on the truck, we have my grandpa's old '77 Impala with a 305 that the slightest exhaust leak would kill mileage and low end torque.

    If you want to throw a little more money at the motor instead, consider a Performer TBI intake, and a set of Vortec 305 heads.

    I think the problem is too much tire and not enough gear.

    Your stock tire would be approximately 30" tall. Your current tires should be approximately 33" tall...

    This alone would give you the equivelent to having the stock tires with a 3.08 gearset. Even to return it to a stock equivelent, you would need to swap it to a 3.73.

    Your displacement reduction throws another wrench into the equation, basically moving the desired gear ratio up another notch to 4.10's
     
  10. DJ Contracting

    DJ Contracting PlowSite.com Addict
    Messages: 1,392

    Thank Derek looks like i will put a converter back on and go to the original size tires
     
  11. schnitz

    schnitz Member
    Messages: 98

    Since I had a '93 Chevy (wrecked it almost two weeks ago) with a V6 and 5 speed (3.73 RG), the best direction, in my opinion, would be go to a set of 4.10 gears. I re-cammed the six in mine and it would tow great at anything above 2,500 rpm in any gear. I was planning on swapping the gears to 4.10's this summer. No need to now. I have an 1800 lb car trailer and went to Hanley Falls Minnesota to get a 10-20 McCormick Deering tractor for my brother. I've got a picture on file that I will post when I figure out how. That tractor tipped the scales at 5100 lbs, so I know the towing feeling. I have no idea on the cam specs, but I know I over-cammed it. I will also say that the little six was not designed for that kind of work, same as the 305.

    But the whole point of my post here is to say before going though the hassle of changing bact to stock tires and converter, try pulling the engine into a more tow-friendly rpm. Gears might be the best bet.

    Chet.