C-20 highway rpm's - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Alex V. · 02-13-2016, 01:32 AM

Quote:

Originally Posted by GTSideSwipe

I have a 69 C/20 350/TH400 with the HO52 4.10:1 rear end and every day I go down the same road and I'm at a solid 40mph @ 2000 rpm. I don't recall what rpm I'm at going 60. I'll have to check tomorrow.

Theoretically it'd be an even 3,000.

GTSideSwipe · 02-13-2016, 02:02 AM

Quote:

Originally Posted by Alex V.

Theoretically it'd be an even 3,000.

True but if I recall correctly it was more like 3300 rpm...

conoco · 10-26-2020, 01:16 PM

I know this is an old thread but I have a 1972 gmc k2500 with the eating. And 4.10. I also have a 4inch lift and 35s

40-50 I am around 2000-2500 rpms.

55-65 I am at 3000-3400 rpms. This is my daily driver and my fishing truck in the summer. I go 65-70 all day long for long stretches often and have no problems. I do have a 383 stroker with 10 grand on it also so I am sure that helps. When I had bo lift and stock tires it would scream around 3700-4000 rpms. It was a bit much but still drove fine if you worw ear plugs lol

tdangle · 10-26-2020, 01:40 PM

Before I swapped in an overdrive auto trans, I was running around 3000 at 60 MPH 4.10 gears with TH350 and 265/75R16 tires. Now right at 2000.

conoco · 10-26-2020, 02:00 PM

Quote:

Originally Posted by tdangle

Before I swapped in an overdrive auto trans, I was running around 3000 at 60 MPH 4.10 gears with TH350 and 265/75R16 tires. Now right at 2000.

I am looking to order the gear vendors of unit for my th350. I should be ready to order hy summer. That will be the best upgrade I could make to my truck and cant wait.

Layne · 02-13-2016, 02:01 AM

My 68 C20 350/400 with 30.5" tires runs 3000 rpm @ 50mph
I assume 4.56 gear. Pretty snappy on the bottom end, but highway is a killer. Takes a while to get a decent distance @ 50 mph.

10-26-2020, 01:16 PM	#3
conoco Registered User Join Date: Nov 2019 Location: Eagle River Alaska Posts: 320	Re: C-20 highway rpm's I know this is an old thread but I have a 1972 gmc k2500 with the eating. And 4.10. I also have a 4inch lift and 35s 40-50 I am around 2000-2500 rpms. 55-65 I am at 3000-3400 rpms. This is my daily driver and my fishing truck in the summer. I go 65-70 all day long for long stretches often and have no problems. I do have a 383 stroker with 10 grand on it also so I am sure that helps. When I had bo lift and stock tires it would scream around 3700-4000 rpms. It was a bit much but still drove fine if you worw ear plugs lol

10-26-2020, 01:40 PM	#4
tdangle Registered User Join Date: Mar 2005 Location: Jurupa Valley, Ca Posts: 1,210	Re: C-20 highway rpm's Before I swapped in an overdrive auto trans, I was running around 3000 at 60 MPH 4.10 gears with TH350 and 265/75R16 tires. Now right at 2000. __________________ Terry 1970 Custom Camper/C20 , GM Crate 350/7004R, Dana 60, factory AC

02-13-2016, 02:01 AM	#6
Layne Registered User Join Date: Nov 2014 Location: Gonzales, Louisiana 70737 Posts: 263	Re: C-20 highway rpm's My 68 C20 350/400 with 30.5" tires runs 3000 rpm @ 50mph I assume 4.56 gear. Pretty snappy on the bottom end, but highway is a killer. Takes a while to get a decent distance @ 50 mph.



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