Rev Limit


http://209.208.111.198/Topic5427.aspx 		Print Topic | Close Window

By NewPunkRKR - 18 Years Ago
What's a good rev limit for these motors?  The 6AL ignition control has it built in, so I figure I might as well use it.  I've got a 6,000 module in there now, is that a good/safe point to use?

- John

By speedpro56 - 18 Years Ago
If your valve springs has approx 90 to 100 lbs spring pressure closed and 250 lbs or more open you should be ok. I would want the heavy duty hollow push rods as well.
By PF Arcand - 18 Years Ago
John: Further to what Gary said, if your valve train is stock, the spring pressures won't be anywhere near what he recommends, & the regular stock pushrods (non tubular) aren't recommended for 6000 rpm. Ford's recommended max for regular valve train was 5400 rpm. Get a advice from someone like John Mummert Y-Block, or possibly Shumann's Sales in Iowa. They advertise Police service valve train parts.  
By NewPunkRKR - 18 Years Ago
I'm not trying to reach 6,000 - my question was what should I expect from my motor.  To my knowledge the internal components are not "upgraded" but it is not original build from '57.  I believe the motor was rebuilt in the late 80's.  So what i'm understanding is that I should put in a module around the 5000-5400 range as a protective measure?

- John

By GREENBIRD56 - 18 Years Ago
The stresses in your engine increase at the square of the speed. The difference in loading between 5000 rpm and 6000 - is about 45%. If you are going to error - go low....
By Pete 55Tbird - 18 Years Ago
It will depend on what cam your engine has. If your peak torque is at 2800 and peak HP is at 4300 then you should plan your shift point to put the engine into this powerband AFTER you shift. Peak RPM is meaningless if you develop less power the higher you rev. The car will be faster if you keep the engine in the powerband.
By pegleg - 18 Years Ago
Pete,

        Not to belabor the point, but gearing has a lot to do with shift points. If the TOTAL torque available to the wheels (Engine torque multiplied by overall gear ratios) drops more by shifting than by exceeding the max hp, then you need to push it. Had this debate with Dad about 50 years ago, he was a firm beleiver in shifting just after max torque. We made several runs with his TR3 to prove it. You will go faster by keeping the highest hp average to the rear wheels throughout the run, whatever that requires.Hehe 

John, when it quits pulling, SHIFT! probably around 5000 with 50 year old valve springs, And read Steve's answer. Fifty year old parts will break, expensively! 

By LordMrFord - 18 Years Ago
How much can rev a stock motor with tubular pushrods and good springs?
By pegleg - 18 Years Ago
Hoosier was going 64-6500 with Ford rods. He's changed gearing to slow it down, and keep the rev's down to 6000. Also with the rules stateside he has to put a roll cage in the car if it runs under 12 seconds. And it will (11.40's)!

    Keep it under 6000 or less

By Hollow Head - 18 Years Ago
MSD 6AL works fine and it's easy to install. And it is cheap as dirt  Smile