What is the MAX RPM i can drive at?????

[mx jim]

I just put a tach in my truck today and i was wondering what is tha max RPM i can drive at for a long distence? I have 3.73 gears i have 350 mtor with th350 trans, And my motor has roller rockers, cmp cam, dart heads, Edelbrock intake, Edelbrock carb, with about 350 hors power. So while i was driving i watched what the tach read, so at 60 i was doing 2700, at 65 3000, at 70 3300, at 75 3600. So i just want to now how many RPMs i can to for a long distence? Thanks for the help James

[mikep]

If you have proper cooling and oil pressure theres no reason why you couldnt run it at 4500 rpm all day long. My boat runs a 350 chevy and that boat is a big heavy sucker and It'll go 45 miles an hour at 4500 rpm for hours on end . Its basically stock with a mild compcams 262H cam.

Mine is built pretty solid on the bottom end and I would be quite contnent running 5500 rpm or higher for hours at a time.

[racedvl]

I have taken my 69 on a couple road trips that were 3 hours each way, and cruzed at 3200 the whole way. . .

[gmc67swb]

Originally posted by mikep
If you have proper cooling and oil pressure theres no reason why you couldnt run it at 4500 rpm all day long. My boat runs a 350 chevy and that boat is a big heavy sucker and It'll go 45 miles an hour at 4500 rpm for hours on end . Its basically stock with a mild compcams 262H cam.

Mine is built pretty solid on the bottom end and I would be quite contnent running 5500 rpm or higher for hours at a time.

MIKE P, DOESN'T YOUR BOAT BENEFIT FROM A FRESH SUPPLY OF COOL LAKE WATER FOR COOLANT? THAT WOULD MAKE IT EASIER ON THE MOTOR RIGHT? COMPARING TO RECIRCULATING 190 DEGREE WATER BACK THROUGH THE MOTOR.

JUST A THOUGHT.

[lukecp]

The motor will take it, but not forever. That is why most older Chevy V8's didn't make it much past 100k miles, no overdrive. The new ones will go about twice as long before needing a rebuild. I don't like to take my truck over 3,000 on the highway (75 mph) because the gas mileage gets pretty bad at that speed. I wouldn't think twice about cruising at 75mph all day, but don't expect the motor to last forever.

[mikep]

I run through a coolant system for the boat with a radiator of sorts that maintains the engine temperature at 180 degrees just like a car does. Its much better not to have cold water circulating through the engine . Constant cold water through the engine never allows it to get to operating temperature and greatly accelerates wear. 180-190 is where you want it to run to get all the engine clearances where they should be for maximum life.

I cant even imagine going more than 100,000 miles before rebuilding a motor.

[gmc67swb]

I HATE TO SAY THIS..NO I'M NOT GONNA..WELL.... ALL RIGHT.. MY DAD HAS 196,000 ON HIS '91 350 AND STILL TRUCKIN'. SORRY DAD I'M KNOCKIN' ON WOOD RIGHT NOW. DON'T WANNA JINX HIM.LOL

[mikep]

I'd feel dirty if I had that many miles on a motor.

I'm only half kidding. Come to think of it I have rebuilt the engine of almost every vehicle I have ever bought used within a few months of purchase whether it "needed" it or not .

[gmc67swb]

I KNOW WHAT IT IS..YOUR GONNA PUT THOSE STEEP GEARS IN YOUR CARS SO YOU WANT TO PUT A FRESH MOTOR IN IT SO YOU CAN SPIN THE DICKENS OUT OF IT THERE BY JUSTIFYING A REBUILD NOW OR IN THE NEAR FUTURE. JUST KIDDING..TIRE SIZE, RIGHT?

[mx jim]

So do you think it is ok for me to cruise at 70 doing 3300 RPM?

[mikep]

Originally posted by gmc67swb
I KNOW WHAT IT IS..YOUR GONNA PUT THOSE STEEP GEARS IN YOUR CARS SO YOU WANT TO PUT A FRESH MOTOR IN IT SO YOU CAN SPIN THE DICKENS OUT OF IT THERE BY JUSTIFYING A REBUILD NOW OR IN THE NEAR FUTURE. JUST KIDDING..TIRE SIZE, RIGHT?

Size matters ! Sorry though. Only 8000 miles on my engine. Its on its second set of heads and its third cam , fourth intake manifold and fourth carburetor. By the time I hit the ripe old rebuild age of 50'000 miles no telling how many combinations I will have tried. I'll probably go 383 next time though. Luckily I work fast or I would have problems...this being my daily driver and all.

[Longhorn Man]

do you think it is ok for me to cruise at 70 doing 3300 RPM

Go for it. It was built to do this.

[72moneypit]

Just be thankful you don't have 4.11 gears! At 65 MPH I'm doing 3800 RPM. I just had the engine/tranny rebuilt (after 105K miles), but like MikeP I accept that the engine will probably wear out again after another 100K miles.

Personally, I use 4000 RPM as the "red line" , so if you do the math, I never go more that 65 MPH or so. I wouldn't hesitate to take a long trip at 4000 RPM though.

[crazy longhorn]

I try to run 3200-3400 on a hyway trip....that put me about 65 with the 4.10 gears, & the 400 hydro. You shouldnt have to worry about the eng coming apart, but milage will suffer in the higher rpm ranges, & rebuilds will be more often as compaired to something with OD. The Richmond trans will let me cruise legal hyway limit in the 2250-2500 range crazyL

[dion]

I get up to 4000-4200 pretty much every day, not for long periods of time though, my work is only about ten minutes from my house but I have taken short trips so on the road for thirty minutes or so and she heated up a bit but nothing too serious. I'm also running a hot cam so that's part of my problem but I'd say you should be fine.

[lpaine]

Higher rpm's = more cylinder wear, I had a '72 Jimmy with 307 and 4.11 gears, the thing was worn right out at about 130k, used a quart of oil about every 500 miles. If your block is high-nickle content this might not be as much of an issue. Also use a good quality oil, maybe even synthetic, and frequent oil changes.

[mikep]

a quart of oil every 500 miles at 130,000? You call that worn out? I'd say thats pretty good. Ive had'em at a quart every 100 !

[kiley]

Holy crap! I'm afraid to run mine over 3000 rpms. I feel guilty and have to pray for forgiveness. On the sand dunes, I've gotten up to 5500 rpms trying to get over a hill but never over 3200 on highway.

BTW, 5500 rpms sounds reaaaalllllyyyy cool through dual exhaust and two chamber flowmasters!

[StingRay]

I have a 373 diff and have run 3000-3500 on lots of trips with my 350 and never had a problem. I have 50 or 60 thou on it now and it doesn't use a drop of oil. Mine was originally a 307 and it was pretty worn out by 80,000 miles but I've been told the 307's had a very low alloy block and were quite prone to wear.

[tom hand]

I have a motorhome with a 454. I don't know what gear it has but it turns close to 4000 rpm at 65. You can't really drive any faster than that because the secondarys on the carb stay open and you can watch the gas gauge move...really. It has 142,000 on it and was on it's second motor before I got it.