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  #1  
Old 10-19-2011, 04:35 PM
JoeDaf JoeDaf is offline
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Rpm range

What is the average rpm range and max rpm for the 300 want to know so I don't blow it up while having fun
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Old 10-19-2011, 06:35 PM
1983F1503004x4 1983F1503004x4 is offline
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Most people who have the 300's and most people who've built the 300 inline-6 agree that 2000 rpm is where peak torque is made, and 3000 rpm is right around where peak horsepower is made. The power curve drops off significantly past 4000 rpm, and if you go past 4500 you risk over-revving the motor, floating valves, and other problems.

The reason a 300 can't rev high is it's long stroke. These motors have a 4'' bore, with a 3.98'' stroke, and using 6 pistons, that makes the 3.98'' stroke a big stroke. If it was a 302 with a 4 inch bore and a 3 inch stroke with 8 pistons, you could go up safely to around 4800-5000 rpm because the piston strokes are an inch shorter. Past that, I'd want the motor balanced and better flowing heads.

The key to remember here, is that the 300 doesn't rev high safely because it doesn't have too. All of it's power is on the down low, which is where you should keep it when having fun.

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Old 10-19-2011, 06:54 PM
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rpms

So are you saying 4000 is about the safest max for reving?
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Old 10-19-2011, 06:57 PM
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A 300 will safely rev to 8,000 if it's build right. Long stroke, sure, but with seven main journals. Plenty of stability there.

From the factory it's pretty much just making noise above 3,500 rpm.
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Old 10-19-2011, 06:59 PM
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Originally Posted by JoeDaf View Post
So are you saying 4000 is about the safest max for reving?
It's probably fine to turn 5,500+ if you can get it there. Without mods it will give out around 4,000 rpm.
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Old 10-19-2011, 06:59 PM
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8000

How in the world can you get 8000 out of a inline six wow
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Old 10-19-2011, 07:08 PM
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rpm

Well I'm getting ready to put an offy dp on mine with a 500 elder with efi exhaust just checking around to see what the motor could turn safely without throwing a rod or something like that don't want anything bad to happen...
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Old 10-19-2011, 07:27 PM
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Same as you'd get 8,000 out of a sbf. Balanced, lightweight rods & pistons, big cam, big head work. Maybe laughing gas or a turbo. Or both. Speed is just a matter of money.

Check out Mighty 6 on youtube. It's a 292 Chevy...but I think he's pumping 800hp at the rear wheels.

With the stock cam you'll have to shift before you can do any damage. Unless you're determined. I've never matted mine for long in high gear but it's not pulling much past 4,500 anyway.
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Old 10-19-2011, 10:06 PM
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My stock internal '84 300 will make an odd "popping" noise if I get it above 4500 RPMs. Almost like it's hitting a 'rev-limiter'.
That's usually the number I feel safe going to on any stock 300. No point in going past that, and better safe than sorry.
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Old 10-19-2011, 10:29 PM
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The stock 1bbl carb, restrictive ports and manifolds, along with the cam all act as a built-in rev-limiter. Getting a 300 over 4500 RPM, under a load, takes patience. Lots of it, too.......
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Old 10-20-2011, 08:43 AM
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With the stock cam and valve springs, you will run out of cam long before you break something, unless you do something silly like rev it in neutral.

According to The Frenchtown Flyer, a former Ford engineer who was involved in the 300 program and who has been racing 300's for decades, the stock rods have a safety margin of 2.7 at 4500 RPM.

If you have the stock YF or YFA carb, you will run out of air flow before you break anything.

Bottom line: If the engine does not have some mechanical problem and you don't do something "silly-stupid" with it, you aren't going to hurt it.
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Old 10-20-2011, 10:44 AM
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Welcome to the forum, JoeDaf!

You have been advised regarding maximum rpms, now I will share from years of driving basicly stock 300's... normal everyday driving can be easily achieved by running the engine between 1000 and 2500 rpms. Moderate progressive power... much like a diesel!
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Old 10-20-2011, 06:34 PM
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Quote:
Originally Posted by 1983F1503004x4 View Post

The reason a 300 can't rev high is it's long stroke. These motors have a 4'' bore, with a 3.98'' stroke, and using 6 pistons, that makes the 3.98'' stroke a big stroke. If it was a 302 with a 4 inch bore and a 3 inch stroke with 8 pistons, you could go up safely to around 4800-5000 rpm because the piston strokes are an inch shorter. Past that, I'd want the motor balanced and better flowing heads.

The key to remember here, is that the 300 doesn't rev high safely because it doesn't have too. All of it's power is on the down low, which is where you should keep it when having fun.

Peace.

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How in the world can you get 8000 out of a inline six wow

Build it right!

Here's FrenchTown Flyer's, I believe he said he's usually turning around 7200 rpms thru the timing lights.


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Old 10-21-2011, 04:35 PM
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Nice runnin drag car there. Stock everything i can usually peak at 4500 and might hit 5k but that is REALLY pushin it!
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Old 10-21-2011, 09:34 PM
JoeDaf JoeDaf is offline
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Sound

Does your motor sound like its reving really high at 3500? and then you pus it even farther?
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Old 10-21-2011, 09:34 PM
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