How much towing can she handle? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

iluvmy72 · 05-14-2005, 09:22 PM

I am wondering what the limits of towning are with a 1972 2WD LB that has a 3/4 ton rear and and TH350(rebuilt w/shift kit) and a 350 engine(headers). It has 3/4 ton leaf springs as well. A friend of mine is wanting to pull a 15000 pound 5th wheel over the rockies. Is he going to be alright? His tranny I'm not worried about because it was built special. But it's that little engine I'm worried about. Can he do it without much lag and slowdown?

ed455 · 05-14-2005, 09:49 PM

It will be difficult if not impossible with the 350. I pulled a 7000 lb. travel trailer over the mountains in West Virginia on I-64. I was using a 15 passenger van with a strong Vortec 5.7 and I topped the highest peak at 42 mph with everything she had.

71swb4x4 · 05-14-2005, 10:40 PM

Trailer brakes are the most important thing, but I would guess that trailer has them. Is your truck set up for trailer brakes? Otherwise he will have to keep the RPM's up, but he'll probably make it.

**StingRay** · 05-14-2005, 10:44 PM

I have a fresh 350 9:1 with 194 heads mild cam,performer and some expensive high end machine work. It's likely in the 275 HP range with very good torque and the truck has a 373 rear end. I have hauled 6 8000 LB loads of water/trailer this weekend and on the dead flat paved highway it is capable but by no means lively. From the feel of the rig with that weight behind it 3/4 ton springs and diff or not I wouldn't dream of putting 15k behind it. You'd need a 410 or 456 diff to even move that kind of weight and hills would be out of the question. 8k is alot of weight. 15K is for a one ton built to handle it. You might try it with a 30 series big block Longhorn with a 410 diff. A Longhorn is a HEAVY duty truck.

TP from Cntl PA · 05-14-2005, 11:05 PM

That is exactly why I pulled the 350 out of my C-20..........You don't have one or two things with them, A. You don't have enough Engine B. You don't have enough gears................In my case I didn't have either. I pulled kicker hay wagons up to one of our mountain farms right after I got mine. They are light but have alot of "aerodynamic drag" .............I got sick and tired of the 350 screaming in 2nd not doing more than 30 mph. So I am putting in something a bit more suited to the job

No doubt in my mind the truck would do it, but your crest some grades at a boringly SLOW speed. The hardest part of towing anything is getting stopped, the rest you can make do with.

tmcgrawlookalike · 05-14-2005, 11:08 PM

i think it is time for someone to do a duramax engine swap?!

iluvmy72 · 05-14-2005, 11:33 PM

see.....I will have almost the same setup as he does however, I will be putting in a Olds 455 instead of the basic 350. BUt I don't really see an issue with the rear end. BUt then again I'm not pulling a 15000 fifth wheel.

72 CustomCamper · 05-14-2005, 11:39 PM

My 72 3/4 ton has towed a 5th wheel trailer with a heavy bulldozer, but it was on flat ground and was straining. At the time it has the stock 350 th350 combo with stock 4:10 gears. As for towing over the mountains I think it would be alot of strain...

Chuck

iluvmy72 · 05-15-2005, 10:26 AM

I guess it all comes down to the amout of ponys the 350 has. For example the one he is using is my old engine which has 360 HP. It's a done-up 69 olds rocket 350 engine. Which is my concern. He is using that engine on loan till he gets his 383 back in there. I'm almost tempted to put the 455 in there and make him use that.

ed455 · 05-15-2005, 10:38 AM

Well, an Olds engine is a completely different animal. They tend to be VERY torqy. I would have more faith in it than the chevy 350 for towing heavy loads, but it's still pretty under strengthed for such a task. Now that 455, yeah baby, that will pull! My screen name refers to the Olds 455.

05-14-2005, 09:22 PM	#1
iluvmy72 Registered User Join Date: Jan 2002 Location: Springville, UT, USA Posts: 1,010	How much towing can she handle? I am wondering what the limits of towning are with a 1972 2WD LB that has a 3/4 ton rear and and TH350(rebuilt w/shift kit) and a 350 engine(headers). It has 3/4 ton leaf springs as well. A friend of mine is wanting to pull a 15000 pound 5th wheel over the rockies. Is he going to be alright? His tranny I'm not worried about because it was built special. But it's that little engine I'm worried about. Can he do it without much lag and slowdown? Last edited by iluvmy72; 05-14-2005 at 09:23 PM.

05-14-2005, 10:40 PM	#3
71swb4x4 Senior Member Join Date: Nov 2003 Location: Brookings, SD Posts: 10,497	Trailer brakes are the most important thing, but I would guess that trailer has them. Is your truck set up for trailer brakes? Otherwise he will have to keep the RPM's up, but he'll probably make it. __________________ Some people are like slinkies, they aren't good for anything, but you can't help but smile when you see one tumble down the stairs.

05-14-2005, 10:44 PM	#4
StingRay Senior Member Join Date: Mar 2000 Location: Saskatoon,SK,Canada Posts: 2,476	I have a fresh 350 9:1 with 194 heads mild cam,performer and some expensive high end machine work. It's likely in the 275 HP range with very good torque and the truck has a 373 rear end. I have hauled 6 8000 LB loads of water/trailer this weekend and on the dead flat paved highway it is capable but by no means lively. From the feel of the rig with that weight behind it 3/4 ton springs and diff or not I wouldn't dream of putting 15k behind it. You'd need a 410 or 456 diff to even move that kind of weight and hills would be out of the question. 8k is alot of weight. 15K is for a one ton built to handle it. You might try it with a 30 series big block Longhorn with a 410 diff. A Longhorn is a HEAVY duty truck. __________________ Saskatoon, Saskatchewan Canada

05-14-2005, 11:05 PM	#5
TP from Cntl PA Registered User Join Date: Apr 2003 Location: Central PA....In the Berg of Nisbet Posts: 790	That is exactly why I pulled the 350 out of my C-20..........You don't have one or two things with them, A. You don't have enough Engine B. You don't have enough gears................In my case I didn't have either. I pulled kicker hay wagons up to one of our mountain farms right after I got mine. They are light but have alot of "aerodynamic drag" .............I got sick and tired of the 350 screaming in 2nd not doing more than 30 mph. So I am putting in something a bit more suited to the job No doubt in my mind the truck would do it, but your crest some grades at a boringly SLOW speed. The hardest part of towing anything is getting stopped, the rest you can make do with. __________________ '72 K-20 EFI'ed 250 Inline/4spd stake body, Farm Truck '71 C-20 Cummins Diesel Powered, In storage thanks to $5.00 diesel! '69 3500 GMC 305V-6/4spd, Still under reconstruction.......... Inlines Rule! 6 soldiers standing is better than 8 laying down!!!!!!!!

05-14-2005, 11:39 PM	#8
72 CustomCamper huh ??? Join Date: Nov 2002 Location: Fredericksburg,Va. Posts: 3,369	My 72 3/4 ton has towed a 5th wheel trailer with a heavy bulldozer, but it was on flat ground and was straining. At the time it has the stock 350 th350 combo with stock 4:10 gears. As for towing over the mountains I think it would be alot of strain... Chuck __________________ 90 Blazer Silverado 350w/ 700R4 and 32" Kelly's "I am a bomb technician. If you see me running try to keep up!" Last edited by 72 CustomCamper; 05-14-2005 at 11:39 PM.

05-14-2005, 09:49 PM	#2
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	It will be difficult if not impossible with the 350. I pulled a 7000 lb. travel trailer over the mountains in West Virginia on I-64. I was using a 15 passenger van with a strong Vortec 5.7 and I topped the highest peak at 42 mph with everything she had.

05-14-2005, 11:08 PM	#6
tmcgrawlookalike Registered User Join Date: Jun 2004 Location: warr acres,oklahoma Posts: 650	i think it is time for someone to do a duramax engine swap?!

05-14-2005, 11:33 PM	#7
iluvmy72 Registered User Join Date: Jan 2002 Location: Springville, UT, USA Posts: 1,010	see.....I will have almost the same setup as he does however, I will be putting in a Olds 455 instead of the basic 350. BUt I don't really see an issue with the rear end. BUt then again I'm not pulling a 15000 fifth wheel.

05-15-2005, 10:26 AM	#9
iluvmy72 Registered User Join Date: Jan 2002 Location: Springville, UT, USA Posts: 1,010	I guess it all comes down to the amout of ponys the 350 has. For example the one he is using is my old engine which has 360 HP. It's a done-up 69 olds rocket 350 engine. Which is my concern. He is using that engine on loan till he gets his 383 back in there. I'm almost tempted to put the 455 in there and make him use that.

05-15-2005, 10:38 AM	#10
ed455 Captain Ed Join Date: Jul 2003 Location: Port Charlotte, FL Posts: 1,241	Well, an Olds engine is a completely different animal. They tend to be VERY torqy. I would have more faith in it than the chevy 350 for towing heavy loads, but it's still pretty under strengthed for such a task. Now that 455, yeah baby, that will pull! My screen name refers to the Olds 455.



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