The Stovebolt Site Forums The Shop Area Engine Shop 250 L6 "Redline"

Lots of folks have Tachometers, or as our UK cousins like to call them, "Rev Counters" in their trucks. There has been a lot of talk about what fits and how to install one. No where in my books or on line can I find a practical "Redline" or maximum RPM number for a mild, street driven 250 L6! I can guess, but does anyone have anything on paper? What good is a tach anyway if we don't know where the danger point is?

Les

i had an old searay boat with a 250 L6. Of course it was cammed differently for marine use rather than car, but the full throttle recommended rpm range was 4500-4800 RPM. that's probably just under a safe operating redline...

The race built 250's see 9000 + rpm ! I don't like to run mine past about 4500, it will go to 5000 easy enough, it just makes noisy I don't like to hear. I would guess the boat rpm above is just about right.

here is a little information that may help http://www.73-87.com/7387garage/interior/factory%20tachometers.htm

The marine engines turn slower to prevent propeller cavitation. A good-condition 250 without much rod bearing wear should go to 6K without any problems other than possible hydraulic lifter pump-up. Keep it under 5K and even the hydraulic lifters should be OK.
Jerry

Thanks for all the replies! What I am hoping for is a printed source, maybe GM, that says, "Maximum RPM is . . ." I fully agree that 4500 - 5000 is the PRACTICAL redline for non-racing purposes.

Thanks for the input,

Les

check a shop manual for the power curve, no point going much beyond where peak power is achieved, probably about 2,500-3000, so really no sense in setting a tach redline past 3500 on a stock engine .... unless you don't care how long it lasts

Bill

Or...if you need to accelerate fast for on-ramps, merges, or the need to downshift to go up a steep incline (i.e. I64W in WV...7-8% grade for 5 miles), or you're just a bit of a hot rodder and like winding through the gears. Not all of us drive like grampas.

Thanks, but I'm looking for PUBLISHED data from about anywhere. I know how to drive my truck and, if the truth be known, I tend more toward the "hot rodder" end of the scale than the "grandpa" end.

I just wanted to know what the factory or the experts had to say, but I guess we are the experts!

Later you all, and thanks,

Les

Les, as I said, the factory "published data" is the shop manual power curve charts, a "redline" isn't just the point beyond which the engine may explode, it's about efficiency

Bill

Your question got me looking into the issue also. From everything I've ever read. The redline of an engine has to do mainly with valve float. On a hydraulic engine, I've seen lifters rated at everything from 5000-7000 RPM. Alot of that has to do with valve springs, push rod deflection, etc...

In my boats, I cruised at anywhere from 3800-4800 RPM all day long.

There's more to the redline issue than just valve float. Balance, oiling, cooling, bearings, and stroke all have a role in the entire scheme of things.

The 230/ 250 engines have a 3.25" stroke, they should be able to rev quick and have reasonable balance at higher RPMs. I'm willing to bet they could do somewhere north of 5000 without any il effects.

Bill, I'm not trying to be a pain in the backside, and I appreciate your input any time you choose to offer it! I have come to the conclusion that that what I want does not exist in printed form for this engine. On the other hand, I have never seen one of these old engines that won't turn up a lot more revs than the torque peak, so torque peak isn't what I'm looking for. Whitedog, What you say makes sense, too. I believe that the 250 was used over such a broad spectrum of applications in so many configurations that there isn't any general "published" data. That is that a high compression, lump ported, cammed, multi-carbed engine with headers will have a different "Redline" than a stock truck engine. It's all in the details!

thanks for all the info,

Les