What should I do?

[spartman]

I have a 1980 K-10 1/2 truck and have been less than impressed with it.

Im not sure if this is where to post this and if its wrong please move it.

What I have is this.

My 1980 4x4 has been a major disappointment to me. I bought it to replace my 79 that was rusted way to far to repair.

In this 80 I put a new GM 350 crate engine in it with an Edlebrock intake and originally the Q-jet the 79 came with. Had the Q-jet totally rebuild by a shop here in town that still knew what a carb was, and even had the throttle shafts rebushed.

I have gotten a holley for it, but havent taken it down the road much to see if that helps any.

The truck has a TH350 tranny and a 205 transfer case.

The gears appear to code out as 2.73's I say appear because the stamp on the rear axle shows PAM which doesnt show up in any thing I have found for axle codes, so Im assuming its actually RAM and was simply stamped wrong. Couldnt ever find a tag on the front axle.

Im also running stock 235/15 tires on it.

The thing gets 10 mpg at best and I can get out pulled by a almost everything.

One time I was helping my mom move from Watertown SD to Omaha and I helped along with another fellow by pulling an 8x16 enclosed trailer full of stuff.

His load was actually heavier than mine and he had an 05 or06 Dodge 1/2 2wd with the v-6 and auto overdrive.

There are some small hills on the interstate on the way down and he could easily go up and down with the cruise set at 75, while I had to put my foot to the floor and haul arse down one hill so I had enough power to climb the next one without slipping below 45 mph.

Also on this same trip I took 4 1/2 tanks of gas round trip, 2 1/4 down etc.

He took 2 tanks and thats only cause he needed the truck for work the next morning.

Im getting 10 mpg at best with this thing and no power. It reminds me of a detroit diesel, it does one hell of a job converting fuel into noise.

I am planing on putting some 3.73 axles I got from a 89 burb under it to hopefully get some power.

If that doesnt work, Im either going to junk the POS or build a 454 and put it in there.

Went to votec with a guy who had a 454 built for towing and he got 10-12 AND had power!

What can I do to make this turd into something else???

I also pulled the beast across the scales at the elevator in town and she weighed in at 5,000 lbs. Seemed a bit heavy for a 1/2 truck to me.

PLEASE??

 

[89Suburban]

Sounds like my truck, lol.

You must be registered for see images

 

[HotRodPC]

If indeed you gear ratio is 2.73 or even 3.08, I say that's your problem. All of things you list about this gutless wonder IMO are related to the gear ratio including gas mileage. Seem many people want taller gears to get better fuel mileage and to some degree there is a bit of truth to that, but your truck is set up to far the other way and putting a mega strain on the motor and drivetrain, working the motor and transmission hard. With an NP205 transfer case, and extra axle and driveshaft up front, that does add weight.

You can't compare these older trucks to modern trucks either. Comparing your power and mpg to a truck that is 25 years newer is like comparing a fat kid playing elementary school football to a thin well conditioned kid playing as a starter on a college football team. Not even a fair comparison.

Do find out for sure what your gear ratio is. You can figure it out by counting the turns.
http://www.gmsquarebody.com/forum/showthread.php?t=3860 <<< Go there to see how to count your turns and find gear ratio. I've made it fairly simple and even listed the most common ratios.

Do you have a tach in your truck? What are you taching at say 50 or 60 mph? I can figure it out that way too.

 

[Old77]

x2 on the gear ratio I'd be you'd notice a HUGE improvement with the right gears. I've got this on my list of "to dos" as well. My rear end gearing sucks and would like to get a 3.73 posi unit in the future. It's makes a world of difference.

 

[spartman]

The tach shows about 2100 at 55. Thats what my swiss cheesed memory is trying to tell me. I havent driven the truck since last summer, so the recollection is a bit fuzzy.

Im thinking that this thing was getting lugged but wasnt sure.

Im sure the comparison wasnt apples to apples, but come on a V-6 with an overdrive???

I should have at least kept up and not gotten trounced so thoroughly.

Im sure the mpg would be different but still......

Ill have to take the cover off and count the teeth and let ya know.

 

[Jims86]

The tach shows about 2100 at 55. Thats what my swiss cheesed memory is trying to tell me. I havent driven the truck since last summer, so the recollection is a bit fuzzy.

Im thinking that this thing was getting lugged but wasnt sure.

Im sure the comparison wasnt apples to apples, but come on a V-6 with an overdrive???

I should have at least kept up and not gotten trounced so thoroughly.

Im sure the mpg would be different but still......

Ill have to take the cover off and count the teeth and let ya know.

2100 is about right, for a 3 speed. I would a vac gauge on it, and check the timing...stock should be 4*

 

[89Suburban]

V-6's rev higher and have an upper rpm power band. He may have been pulling that hill at 75, but it was not in OD I can guarantee that. My buddy's v-6 S-10 was the same way, that truck would haul ass up a mountain with a trailer and quad on it. It's all in the upper rpms on those vehicles.

You can pop your rear cover off and there should be numbers stamped on the ring gear for the ratio.

 

[spartman]

2100 is about right, for a 3 speed. I would a vac gauge on it, and check the timing...stock should be 4*

4 degrees timing??? The stock sticker shows 10 and Ive been told to push it to 12.

The vac gauge shows a nice 15-17 when running constant. Drops to 10 without much effort from the pedal.

Will idle at 17 warm, hits 20 on cold fast idle.

That reminds me, the dizzy is an accell dizzy I bought new for the engine. Its got the stock spring configuration in it as well.

Currently its set for the stock 10 degree advance.

 

[HotRodPC]

You didn't give me a full tire size. 235/ What 15???

 

[HotRodPC]

Taking a guess at 235/65 R15 you've got 3.08 gears. That's your problem with it being a sled. Also follow the tuning specs being given.

NO, you don't have to take the cover off. You can also count the turns with one wheel in the air. I posted the link up there in my post.

Do find out for sure what your gear ratio is. You can figure it out by counting the turns.
http://www.gmsquarebody.com/forum/showthread.php?t=3860 <<< Go there to see how to count your turns and find gear ratio. I've made it fairly simple and even listed the most common ratios.

 

[spartman]

Stock size of 235 75 15

So are you saying I should set the timing at 4 degrees or I should follow what the factory spec on the emissions sticker says?

i dont even set my old Allis Chalmers tractor that low in timing and that only has about 6:1 compression.

 

[HotRodPC]

Stock size of 235 75 15

So are you saying I should set the timing at 4 degrees or I should follow what the factory spec on the emissions sticker says?

i dont even set my old Allis Chalmers tractor that low in timing and that only has about 6:1 compression.

It's safe to say you have 3.08 gears with a 28.8 inch tall tire 2100 rpm @ 55mph.

I'm sure the 4 degree BTDC is at idle. What's even more important than that, are you sure getting advance timing? Either by vacuum or centrifical? Sometimes the plates and weights can rust and seize also and you'll never get close 31 degrees advanced timing at higher rpm. That too is a problem and will cause you to have a sled.

 

[crazy4offroad]

You say you got a new crate engine but what HP was it rated for? They come in several levels of power available. If you chose the cheapest, you get what you pay for. Those gears are the obvious problem, and if your memory is correct on the tach/speed reading, then you don't have 2.73's. I got a buddy who does and he says he turns 1800 rpms at 65 mph but he has an SM465. According to the gear ratio calculator you should be turning about 2,000 rpms at 65 mph.

You could try a few things: add more power to the motor with a cam that has a lower torque band, maybe throw on a pair of Vortec heads, and improve exhaust flow with headers. Or change those axle gears, you're probably out of your torque band by about 400 rpms. Or start further diagnosis (which probably should be done first) - is it possible the cats are getting stopped up? What size is the exhaust? What was the actual timing supposed to be set at for the crate engine, NOT the sticker under the hood? Is the carb providing the best air/fuel ratio your engine needs? You know the q-jet was never known for excellent fuel economy when those big secondaries open up. Is there any possibility of a vacuum leak? 15-17 is a little low, mine new with Edelbrock Performer cam still pulls a solid 21" of vac, yours with stock cam should do just as well.

Hope something here gets you looking around at other possibilities of power loss in your truck besides "it's a turd" or "it's a piece of ****". Stuff like that just says it has more to do with your own shortcomings than blaming the brand. Usually when people are down-talking their truck at a forum like this dedicated to those trucks, they don't usually get much help, especially from me. But don't let my criticism get to you though, pull this **** at a place like Pirate and see how bad you get ripped. We just want to help and when it starts acting like it should, we want you to be happy with the Toughest, Longest-Lasting Truck On The Road!

 

[spartman]

You say you got a new crate engine but what HP was it rated for? They come in several levels of power available. If you chose the cheapest, you get what you pay for. Those gears are the obvious problem, and if your memory is correct on the tach/speed reading, then you don't have 2.73's. I got a buddy who does and he says he turns 1800 rpms at 65 mph but he has an SM465. According to the gear ratio calculator you should be turning about 2,000 rpms at 65 mph.

You could try a few things: add more power to the motor with a cam that has a lower torque band, maybe throw on a pair of Vortec heads, and improve exhaust flow with headers. Or change those axle gears, you're probably out of your torque band by about 400 rpms. Or start further diagnosis (which probably should be done first) - is it possible the cats are getting stopped up? What size is the exhaust? What was the actual timing supposed to be set at for the crate engine, NOT the sticker under the hood? Is the carb providing the best air/fuel ratio your engine needs? You know the q-jet was never known for excellent fuel economy when those big secondaries open up. Is there any possibility of a vacuum leak? 15-17 is a little low, mine new with Edelbrock Performer cam still pulls a solid 21" of vac, yours with stock cam should do just as well.

Hope something here gets you looking around at other possibilities of power loss in your truck besides "it's a turd" or "it's a piece of ****". Stuff like that just says it has more to do with your own shortcomings than blaming the brand. Usually when people are down-talking their truck at a forum like this dedicated to those trucks, they don't usually get much help, especially from me. But don't let my criticism get to you though, pull this **** at a place like Pirate and see how bad you get ripped. We just want to help and when it starts acting like it should, we want you to be happy with the Toughest, Longest-Lasting Truck On The Road!

The engine I purchased was the basic GM replacement 350 engine. I knew it wasnt going to be a barn burner, but was hoping for more than its delivered.

I would have to see a major reason to change to those Vortec heads.
2100 rpm for a TH350 is within the range of rpms.

I am going to change the axles to 3.73's so that should help.

Truck has no cats, dual exhaust with 2.5 inch pipes and what the shop called "turbo" mufflers. He stated that they were basically a smaller version of a stock muffler.

When I purchased the engine from the dealership they stated to follow the sticker of the vehicle.

I have replaced the Q-jet with a holley but have not had a chance to truly run with the holley due to the fact that I parked it last fall due to frustration.

If I hadnt, I would have pulled the engine, and crushed the truck.

What does my shortcomings have to do with this truck? I have compared it to other pickups of similar age and if you read my earlier posts you would have noticed that this truck replaced a 79 1/2 ton chevy that I had no complaints with.

Yes I have read about those lovely "people" over at pirate. I have no desire to get into an argument with any of those people, I prefer to try and help before I call the poster a moron etc.

I am doing my best to not be an ass and to provide as much information as possible.

Im being more than accepting of this truck since Im a ford person myself. I keep this truck because it has sentimental value to me.

It seems that the biggest issue with this truck is the gear ratios in it. I will get the axles changed and then start to drive it again.

I will let the truck tell me what it wants me to do from there I guess.

 

[HotRodPC]

You'd be much happier with 3.73s and if you plan on a jump in size, anything above a 33 in tire, I'd consider 4.10's. 3.73's in used half ton axles are out there to be found, in 3/4 ton axles, 4.10 is pretty common but they you'd have to do 8 lug wheels.

I'm certain if the #'s you gave us, you have 3.08 (3.07) ratio now. Mathematically it's about 200 rpm off, but figuring a NON Lock up converter, you're losing about 200 rpm, so I feel confident you have 3.08/307 ratio. Should be a 12bolt rear and a 10 bolt front.