top speed question

[mrsmothers]

Hi I have a 71 c10 with a three on the tree and a 350. I am about to get the truck back on the road in a few days and I was wondering, I do a lot of hwy miles do you think the truck in going to be able to run 70 to 75 with no problems or is that going to be pushing it? It also has the 373 gears in back.

[dan42]

70 to 75 will be pushing it a little. It would be fairly comfortable at 60 but depending on the tire size you'll be over 3000 rpms at 70-75.

[dwcsr]

Mine does.

[BossHogg69]

Before I tore my '69 apart, it also had 3.73's, a TH400 trans, and a stock 454, and 275/60/15 tires. It would do 70-75 on the highway but it was a little buzzy and drank gas. 65mph was better, but it liked 60mph best and got much better mileage there.

[Notrodder]

I had a '76 3/4 ton, 350/350, w/3.73's and pizza cutter tires (235/85's), stone stock and got the thing going 120mph once. It was SCARY!, 'cause it felt like it was on 'tiptoes' with very little weight on the road.

If your rig is in decent shape, it should have no problem doing 70-75mph all day long.

[swamp rat]

My truck loves doing 70/75.. 350/350 with 373's and 33's

[rsavage]

Just my opinion, but unless I had a motor that was fresh and built right, I wouldn't expect it to have any longevity if I was consistently turning it at 3000 rpms for extended periods of time on the highway. Engine rpm's in final drive are going to be dependent not only on gear ratio in rear end, but also on tire height. I've always felt that 24-2500 rpms was a good cruising rpm, but that's just me.

[cdowns]

it all depends on how well you maintain it

[special-K]

These trucks have run at hiway speeds all these years with no problem.The problem is people are used to vehicles with overdrive these days.I've run trucks with 4.10 rears all day long at 75 mph.It's a Chevy,don't worry about it.

[cam.man67]

70 to 75 won't do any favors for gas mileage, but I have an equally equipped '69 that has no problem running at that speed. 95 is about all I've ever done, due to traffic and the fact that I have manual brakes.

[SWEET7T]

My '70 has 3.08 gears, 255/70/15 tires and the speedo is dead on. At 75 I'm turnin right at 3000. Ran it that way for 2 years driving slightly over 400mi each way going to/from college almost once a month.

I've been from southern Arizona, to Idaho, Nevada, and everywhere in between in that truck. I never held a speed higher that 75, but I had spun over 100mph a couple of times.

[americanmusc1e]

I've got a 3.73's and I've driven mine in 3rd (direct drive) plenty of times due to problems with the 700r4 and it cruzes perfectly at 70-75 and 3600rpm.....

I've had it to 6000 in third gear too (120-130mph i'm not sure) and mine does quite well at high speeds though I wouldn't put that much load on my motor for too long

[lil hoodlum]

My '68 has a 350 smallblock, 3 speed manual, and I guess 3.75 rear end, and I consistantly run it 70 -75 mph on the highway. My truck seems to like it but with a 4 barrel edelbrock it does drink a lot of go juice. 60 -65 mph is much friendlier though. I have also driven it 80+ mph and I felt like that was pushing it too much. My motor is a bone stock and on its 12th year on a rebuild.

I sometimes wonder how much longer will it last.

[prostreetC-10]

Try doing 70 mph with 373's and a couple of M/T prostreet 18.5 4 ply bias tires.....it's like doing 70 on hot air balloons. I can't wait to get my prostreet radials!!

[raycow]

Back in the day, it was uncommon to get 100,000 miles out of an engine. Today's engines last longer because they are better of course, but taller gearing is also responsible for part of the improvement.

Overdrive was optional with a manual transmission until 69, and the buyers who were knowledgeable enough to order it were rewarded with increased engine life along with quieter running and reduced fuel and oil consumption.

Ray