Rpm

[HELENT]

What is max rpms on a 59ab stock

[V8COOPMAN]

Probably a few more than a stock 59A is likely to produce. DD

[Bluebell]

V8 Coopman is the answer to his question 3600 rpm?
Early war (1939) they were full out at 3200 rpm, with max torque at around 2800rpm.
That's just a shot from my memory (which now days operates on a modern system. Fuzzy Logic!)

[deuce_roadster]

If your question is regarding to what is safe, I would think the valves would float before you hurt a stocker. If it is what is max power look up a torque curve for your particular engine. Probably close to what Bluebell suggested.

[Ol' Ron]

Get JWL"s book. The first half of the book is the modification of the stock 239ci engine. With out changing the cam the best it can do is 3700 and can't produce a 1oo HP no mater what you do to it. I'm sure it will rev well over 4K in 1st gear, but after 3200, it's all down hill. Buy the book, many facts and myths busted.

[Ronnie]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Ol' Ron

Get JWL"s book. The first half of the book is the modification of the stock 239ci engine. With out changing the cam the best it can do is 3700 and can't produce a 1oo HP no mater what you do to it. I'm sure it will rev well over 4K in 1st gear, but after 3200, it's all down hill. Buy the book, many facts and myths busted.

+ 2 on that.

R

[Mart]

I had my roadster timed at the weekend and turned 94.14 mph. With 4.11 gears and 7.50:16s thats 4400 rpm. that's a 4" french motor with an isky max1 cam, twin 94's on a Thickstum PM7.

Mart.

[Bruce Lancaster]

Flathead lower end is good for far more speed than the breathing can handle in stock or typical rod engines...allegedly this is the property that caused Duntov to start thinking about a new top end...
Duntov was a smuggler right after WWII, running things that were highly taxed in one place but not another across borders on back roads at night, low countries--France-- Germany, in a '37 Ford.
He discovered that a heavily loaded '37 would rev WAY beyond the limits it could reach under power when it was going down a long hill...reaching close to 7,000.
It could not possibly get there on its own without intervention by lots of gravity, of course, but when it went there it did not blow up. The RPMS were far greater than Duntov's prewar French DOHC race car could reach.
Conclusion: How about putting something new on top?

[JM 35 Sedan]

I was going to post my best guess at ~ 4k yesterday, when I first saw this but thought the engine gurus here would be best to comment on this one. I know I have over revved my little 21 stud a few times. That's one reason why I would like to hookup a small 6V tach in my '35 as mentioned in a recent post about tachs.

[V8COOPMAN]

Originally Posted by HELENT

What is max rpms on a 59ab stock

Originally Posted by Bluebell

V8 Coopman is the answer to his question 3600 rpm?
Early war (1939) they were full out at 3200 rpm, with max torque at around 2800rpm.
That's just a shot from my memory (which now days operates on a modern system. Fuzzy Logic!)

I guess I mis-read the term "max rpms" in the question to be something like a safe, REDLINE rpm speed. DD

[36-5window]

Does anyone actually KNOW when the valves float on a STOCK flathead?? Only way I could float the valves on my 1953 V8 was to down-shift to 2nd gear at 70 MPH!!

[Bruce Lancaster]

Only one I have ever floated was a very tired stock 59 in a friends '38 pickup...it floated WELL before the stock power curve ran out, once nearly causing me to nearly lose intersection priority to volvo wagon!
History was unknown, but since the engine was a smoking, dripping heap of scrap iron my guess is that the engine had been violently overheated and the springs cooked out.
I know racers who have discovered that the special springs they bought from their cam suppliers were entirely unnecessary, including on a roller setup on a very fast car.
Stock setup is light and direct and good for anything you can do to it, even though it is possible to assemble the springs to the valve assemblies by hand!

[Walt Dupont--Me.]

My dragster has been screaming for 3 yr's with no trouble with the engine. I've broke everything else, rear ends, trans, clutch ect. Twisted the drive shaft right off taking off at the lights. Before my boy could get his foot off the gas the recall on the tach read 7100 rpm. The engine is a 286, Potvin 425 cam, 3--94's, I have the center main beefed up with a strap. We usually go through the trap at 5500. OHHH, Esky springs set up 80# seat pressure. BTW a stock flathead valve spring are only 42# seat pressure. Walt

[Flathead]

That Potvin 425 Eliminator is a great cam.

[Ol' Ron]

Run all my L-100 at #50

[Tom Walker]

When the valves float do they get a big hike in hp with all that extra duration?! Sure I read that in bike tuning book!