1991 c2500 , can it tow 6000lbs trailer.

[Edmduncan]

It will pull that at 55 to 65mph without breaking a sweat! If that is a 8 lug C2500 your chassis can easily handle 10K, the question becomes can that Swirl Port 350 maintain speed! And unless you live in the Rockies the answer is yes. A 350 TBI can run all day at 2,500-3,500 RPM varying loads as long as it has enough cooling, sufficient oil pressure, and proper spark. People don't realize that 20 years ago this is how folks went camping before the Diesel Wars! My 93 K1500 with 300,000 miles and much less compression than you just tugged a 8ft tall 4,000lb trailer 800 miles round trip through hilly Northern MI at 60mph in 4th (NV3500) no questions asked. It's ok to downshift going up a long grade!

The best thing to do is take it for a test run as is! See how well it pulls, handles, and brakes. After that you know what you're up against. If I owned that truck I would add a high flow air cleaner, headers, high flow muffler, a stack plate trans-cooler with an E-Fan, and last but not least a trans-temp gauge. With a proper brake controller and those heavy rear leafs she should handle like a dream!

I have swapped many a LS before, a 6.0 will not be worth the hassle. A TBI 7.4 however would be an easy weekend project! Do not set your base timing further than 4 degrees ADV, 30 seconds into a long grade the last thing you want to find out is that your knock sensor is not plugged in.

Good luck!

Thank you, I already have a bunch of the things you mentioned on the truck.
High flow kn air filter, sadly stock exhaust manifold with an 3" fully welded high flo exhaust with no cat. Putting a tbi plate in tomorrow, and the truck has a trans cooler on it already that my trans guy said is good.
It is 8 bolt semi floating rear, i was advised not to put a trans temp sensor on as by the time it reads damage is done and its another leak point ( trans mechanics words when asked about putting one in) and ive upgrade the brake controller to the reese towpower 8507.
So maybe heads down the road for the engine lol.

 

[alpinecrick]

so in an effort to come to the experts and the people that have real world experience I'm asking the question.
I have a 5200lb dry travel trailer and the truck is as follows.
1991 C2500 350tbi with Z82 package, dual battery, trans cooler, heavy rear leaf springs.
4l80E trans, with shift kit and 3:73 rears.
Compression test on engine 140/150 and in between across the board, so within 10% variance.
Everything that can be external on the engine has been replaced or serviced within the last 6 months. Complete tbi clean and all new everything except injectors as they are throwing cold cone pattern.
Engine is strong, transmission serviced and pristine mechanic said.
The truck is in good shape as it was very seldom driven and been family owned since new.
135000 miles / 217000km.

I just want opinions as to if it will tow ok, should I adjust timing, or anything that maybe a good upgrade. Don't get me wrong if I can tow i will keep the 350, but a ls swap isn't out of the question for fall lol.

Absolutely with that rig--just don't plan on going uphill very fast.......

I had a 91 light K2500 with 5.7 and NV3500, and in the early/mid 90's towed a 19 ft TT around the Rockies 5k to 10k in altitude. This was an early 80's trailer, and dry it had to be 4000lbs -- 4500lbs, and I usually towed it with water tank full, plus all the other camping/hunting gear.

 

[skylark]

i was advised not to put a trans temp sensor on as by the time it reads damage is done and its another leak point ( trans mechanics words when asked about putting one in)

So you're saying that the guy who builds trannies for a living is telling you not to monitor your transmission temperature while towing... This is like a dentist giving lollipops to kids after appointments!

 

[Edmduncan]

So you're saying that the guy who builds trannies for a living is telling you not to monitor your transmission temperature while towing... This is like a dentist giving lollipops to kids after appointments!

Yup I asked him about puttng in a trans temp guage and he said it wasn't worth it. By the time it gets hot enough to be a warning the damage is already done. Maybe because I already have a trans cooler on it , and a guage would be over kill. I don't know I am abiding by what he said though he is one of the best in the city and has had a few of these trucks himself. I know it sounds odd but I'm trusting in his advice, maybe next yr in spring I will
Look into it again.

 

[92Raiderburban]

6.0L/4L80E/4.10 gear is fairly gutless pulling an empty 15 passenger van IMO. I would get a 454 Vortec or an 8.1 if you engine swap.

Im right there with you. I know a guy with a 6.slow that had trouble towing 7k on a 6% grade. The vortec big blocks u mentioned are torquers and would do it alot better,with ease. My favorite tho is not even a chevy motor: cadillac 472. 550lb ft at 3200 rpm 380 hp at 3800 rpm and weighs only 60lbs heavier than a small block. I have one in my 80 squarebody

 

[Erik the Awful]

My favorite tho is not even a chevy motor: cadillac 472. 550lb ft at 3200 rpm 380 hp at 3800 rpm and weighs only 60lbs heavier than a small block. I have one in my 80 squarebody

...and the torque curve starts at idle. I wish they were easier and cheaper to find.

 

[Bloodwater79]

depending on your gearing, the 2500 with the 350tbi I think is maxed at 7500lbs trailer. if you have 4.10's, 4.56, or 454 or diesel you ar looking at 9000lbs trailer GVW
If you look up some trailering websites they will have a guide that you input the truck/vehicle info and they will pull the info for you

 

[stutaeng]

Yup I asked him about puttng in a trans temp guage and he said it wasn't worth it. By the time it gets hot enough to be a warning the damage is already done. Maybe because I already have a trans cooler on it , and a guage would be over kill. I don't know I am abiding by what he said though he is one of the best in the city and has had a few of these trucks himself. I know it sounds odd but I'm trusting in his advice, maybe next yr in spring I will
Look into it again.

That sounds like baloney, honestly. They put transmission temperature gauge in all 2500/3500 in later generations of these trucks, probably to help tell the driver when it was time to pull over if temperature of fluid got too hot. But in reality, the 4L80e would be the least of your worries, they hold up very well pulling heavy loads, and at the end of the day 7,000 lb is not a ginormous number.

The trailerig package should have given you a transmission oil cooler, engine coil cooler and power steering oil cooler so translates to a vehicle equipped for towing on a daily basis. Double check that you have the later two.

This may help you:

http://trailers.com/tow-capacity/in.../GMC&model=C2500 Pickup (2WD)&template=normal

It's listed with a 4.10 gear ratio, but by just taking a simple ratio for a 3.73 puts you in the low 8,000 lb capacity. But better check the Owner's Manual. Also make sure the trailer has it's own brakes with a brake controller. I think stopping would be more challenging than pulling.

 

[92_Bahama]

Thank you, I already have a bunch of the things you mentioned on the truck.
High flow kn air filter, sadly stock exhaust manifold with an 3" fully welded high flo exhaust with no cat. Putting a tbi plate in tomorrow, and the truck has a trans cooler on it already that my trans guy said is good.
It is 8 bolt semi floating rear, i was advised not to put a trans temp sensor on as by the time it reads damage is done and its another leak point ( trans mechanics words when asked about putting one in) and ive upgrade the brake controller to the reese towpower 8507.
So maybe heads down the road for the engine lol.

'
Haha Right On! Headers for these trucks are dirt cheap, just watch your plug wires around em. I would highly recommend running a trans temp gauge, every GM truck GMT800 for HD's and GMT900 for 1500's include them factory now. Personally I would use this opportunity to install a nice B&M deep, finned trans pan. And before you put that puppy on weld a bung on the side of the pan so you don't have to use the drain plug for your temp sensor, makes it really easy for the wiring to get snagged if you use the drain plug. You can also install T fittings into your trans lines that will give you a more accurate reading than the inspection plug. If you want extra credit and own stock in an electrical supply company you can always install two T-fittings to view your fluid temps right as they leave and return to the trans, gives a good idea on how well that cooler is working! I highly recommend GlowShift Gauges, you can usually get a good deal multiple gauges and add oil temp, vacuum, etc. If those aren't your style a knock off Auto Meter gauge will always do the trick!

The fact that your truck has been in your family since new and unmolested makes me really hope that you end up giving the original power plant a chance!

 

[Edmduncan]

'
Haha Right On! Headers for these trucks are dirt cheap, just watch your plug wires around em. I would highly recommend running a trans temp gauge, every GM truck GMT800 for HD's and GMT900 for 1500's include them factory now. Personally I would use this opportunity to install a nice B&M deep, finned trans pan. And before you put that puppy on weld a bung on the side of the pan so you don't have to use the drain plug for your temp sensor, makes it really easy for the wiring to get snagged if you use the drain plug. You can also install T fittings into your trans lines that will give you a more accurate reading than the inspection plug. If you want extra credit and own stock in an electrical supply company you can always install two T-fittings to view your fluid temps right as they leave and return to the trans, gives a good idea on how well that cooler is working! I highly recommend GlowShift Gauges, you can usually get a good deal multiple gauges and add oil temp, vacuum, etc. If those aren't your style a knock off Auto Meter gauge will always do the trick!

The fact that your truck has been in your family since new and unmolested makes me really hope that you end up giving the original power plant a chance!

I've put allot of work into refreshing everything on the truck so we are wanting to try to keep the original 350 over a swap.
I have replaced everything on the outside of that engine in the last 3 months, with the exception of front of the engine( belts, pumps alternator) but thats a winter job as i would rather have them new and the old ones as back up. The truck has never been winter driven and never will so lots of time to change everything out and refresh everything from bumper to bumper.