Hi all, I have a 1993 K1500 extended cab short bed step side w/ the 350 and I think the 4l60e and the semi float 14 bolt rear axle and I'm thinking of re-gearing the truck. My reason is it feels like it has plenty of power just it doesn't accelerate as well as you would expect with it having that much power and changing the gears in the diffs is easier than changing tranny gears, although I don't know what gears are in it right now. Thanks in advance for the information and suggestions.
New gear ratios for my truck
- Thread starter Powellbr
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The 350 doesn't really have very much power, even by gas motor standards. It was OK in 1993, but makes <225 HP from what I can tell. Compare that to modern motors, such as the 2.5L in the Malibu (152 ci, less than half the size of the 350) which makes 198 HP... So it is probable that it feels slow, because it just is slow. 225 HP in a heavy truck doesn't go as far as 198 HP in a small car.
If you do want to change the rear end for better acceleration, you will lose fuel economy, and arguably shorten engine longevity. The old 350 didn't like to sit at high RPMs all day. And at the end of the day, you aren't making any more power, you are just sacrificing top-end performance for a better 0-60, or probably really just a better 0-30 MPH. It won't help you towing or climbing hills, unless you just happened to be in-between gears now.
If you live in a non-emissions test area (or can work with the referee to make the swap legal), sticking in a junkyard 5.3L or 6.0L LS motor would net you a HUGE amount more power, though with a bit more work than a rear-end swap.
If you do want to change the rear end for better acceleration, you will lose fuel economy, and arguably shorten engine longevity. The old 350 didn't like to sit at high RPMs all day. And at the end of the day, you aren't making any more power, you are just sacrificing top-end performance for a better 0-60, or probably really just a better 0-30 MPH. It won't help you towing or climbing hills, unless you just happened to be in-between gears now.
If you live in a non-emissions test area (or can work with the referee to make the swap legal), sticking in a junkyard 5.3L or 6.0L LS motor would net you a HUGE amount more power, though with a bit more work than a rear-end swap.
Does it only make 225? Wow that sucks. My 93 Dakota with a 318 make 230. That's what it's rated at anyway.
I just Googled some stock dyno charts, and that's what came up. I've owned some 350s in the past, and honestly, 225 feels about right. The other thing you could do if you don't mind pulling the motor is to build it up. Performance parts for the 350 are dirt cheap, and that would solve your issue for sure.
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With living in central Utah emissions would cause me no qualms, I can't stand LS based engines in cars/trucks that didn't come with an LS pattern engine, don't know why, and have thought about stroking it to a 383 and putting twin turbos on it with a FAST EFI system, MSD ignition systems, and a 20 circuit InfinityWire wiring system but I've only just started working at Walmart in the TLE dept so I don't have all that money
wubba lubba dub dub
The 14 bolt semi float is EXTREMELY rare to find in a K1500, and even RARER to find it in a non vortec one unless it was special ordered with a camper tow package. Are you sure it has a 14 and not a 10 bolt? As to the gear ratio, you can look in the glove box for the code. GU6=3.42, GT4=3.73, but being a TBI truck don't be surprised if you see a GU4 code for 3.08 gears. I have an 88 outside thats a 350 2 wheel drive wth 2.73's in it.
Could also be the 205HP TBI engine. Even the 96+ 5.7L VORTEC was only 255HP, and the TBI in stock form is a FAR cry away from a stock VORTEC. In stock form they have good pull right off idle, but they CHOKE at 4K RPM's due to GM's piss poor castings with the swirl port heads in stock form. I've done a few for people, and woke them right up on a modest budget, but it does take a GOOD bit of head work to make them run decent. If done right, they will pull HARD, and make you 2nd guess that it's not a big block from the bottom end torque. My uncle ripped up 2 4L60E's in his before he finally bit the bullet and had me put a good kit in it with a SUNCOAST converter. The TBI engines with swirl port heads are never gonna be high RPM high HP engines, but they can make GREAT truck engines.
Theres nothing wrong with the TBI setup, IF its setup correctly. Nothing against an ls swap either, I just prefer the old school tbi for simplicity myself. That, and most 93 trucks aren't worth doing an LS swap to. The cost of the engine and swap is more than the truck is worth.
Funny, I have found the cost of buying a junkyard LS & trans then dropping them in is less than a good EFI conversion, at least into a Chevy. Heck, all it costs is a couple motor mount plates, an EFI license, and possibly driveshaft(s) depending on what trans was in the old truck to begin with. That and the purchase price of the motor, which seems to be randomly between $1k and $3k for a working engine/trans/harness pull. Though I suppose that does risk exceeding the value of the vehicle, so does an EFI swap, IMO. It is just at the end of the day, for the same money, I would rather have a LS (with all the power & reliability) over an EFI swap on the same low-output 350.
If it were my truck, I would pull the existing motor, and start throwing in eBay performance parts. Hard parts for the 350 are stupid cheap, and with a thousand bucks or so in upgrades, it will move right out :thumb:
That'll be a little hard right now seeing as its at the shop for a new rear main seal, if it's got center bolt valve covers is it the vortec? And I'm sure it's the sf 14, I read online somewhere a while ago that the diff cover was supposed to have the gear ratio printed on it. It didn't. But I did count the number of bolts holding the cover on 3 or 4 different times so unless I screwed up 4 different times it's the sf 14
wubba lubba dub dub
Center bolt valve covers started around 87, VORTEC's didn't start until 96 for the V8. 93 is a 193 swirl port head engine.
And yes, your truck is already EFI with a throttle body injection system. What I believe they mean by EFI is MPFI, or multi port fuel injection. Theres nothing really wrong with the TBI setup IMHO. Swap over to a 94-95 big block throttle body, put a 94-95 fuel pump in the tank(94-95 big blocks ran at 32 psi, all the small blocks, V6's, and big blocks to 93 ran at 8-13 psi), cam swap, set of headers, 3 wire O2 sensor, open exhaust, port your current heads and intake, and it will run like a COMPLETELY different truck. Next weak link will be your trans, so save up for it. I have yet to not have one lose a trans after I've done an engine for one. The amount of off idle torque the swirl port heads can make is RIDICULOUS! But it will NEVER be a speed demon unless you want to put a set of heads on it, and spend some money on it. Swirl port heads work great for stump pullers, RV's, and airboats.
And yes, your truck is already EFI with a throttle body injection system. What I believe they mean by EFI is MPFI, or multi port fuel injection. Theres nothing really wrong with the TBI setup IMHO. Swap over to a 94-95 big block throttle body, put a 94-95 fuel pump in the tank(94-95 big blocks ran at 32 psi, all the small blocks, V6's, and big blocks to 93 ran at 8-13 psi), cam swap, set of headers, 3 wire O2 sensor, open exhaust, port your current heads and intake, and it will run like a COMPLETELY different truck. Next weak link will be your trans, so save up for it. I have yet to not have one lose a trans after I've done an engine for one. The amount of off idle torque the swirl port heads can make is RIDICULOUS! But it will NEVER be a speed demon unless you want to put a set of heads on it, and spend some money on it. Swirl port heads work great for stump pullers, RV's, and airboats.
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Unless it was a car, then it could have had center bolt valve covers with a carb on it. It was screwy that GM changed the block and cranks in 86, but waited until 87 for the head change.
So now my truck has another issue. I picked it up from the shop yesterday because it was getting a new rear main seal installed and I noticed it was sounding like one of the rocker arms on the driver side was lose again, my guess was it was the intake rocker for the #3 cylinder, and I noticed today that the oil pump either isn't pumping at nominal pressure or there's a problem with the oil pickup because it was at ~15 psi instead of the normal ~45 psi. Has anyone ever had this kind of problem after replacing the rear main seal? I also noticed that the pan was overfull by ~2 quarts and had some kind of small particulate in the oil also. I hope it's nothing too expensive to fix.