The Ford Barn

kingskid · 03-03-2022, 04:15 PM

New to me: 47 Ford business coupe. It has 59AB with Offy heads,Offy intake 2 97's carbs, Isky 400 cam stock 3 speed trans. As far as I can tell stock rear diff. What would be a comfortable RPM on highway speed say 60-65?

51 MERC-CT · 03-03-2022, 04:20 PM

Need differential ratio and tire dia to give any meaningful figure.
( other than that 2500 ±)

40cpe · 03-03-2022, 04:38 PM

"Comfortable cruise RPM" is what it is regardless of other factors. My '38 has a 3.78 rear and 29" tires. 60 MPH is about 2700 rpm and the car and I am comfortable there.

tubman · 03-03-2022, 06:06 PM

I have 3.55's and 2.25/75R15 rear tires in my '51 club coupe with a '51 Merc with a stock cam, no overdrive. I find that 2700 RPM is the maximum comfortable cruise speed. On my car, that's about 70 MPH. I find these engines like to run at 2300-2700 RPM.

woodiewagon46 · 03-03-2022, 06:23 PM

R.P.M. equals, MPH times gear ratio, times 336, divided by the tire diameter. That will tell you what you have now.

ford38v8 · 03-03-2022, 08:15 PM

Sponsored Links (Register now to hide all advertisements)

Well, assuming that 6.00 16 Cokers are 29" diameter ?, I did the math posted by woodiewagon46. My '38 Conv Cpe purrs at 70 mph, to my ears sounds and feels better than at 65. I have 3.78 gears, which puts my rpm at 3066. My engine is a 59L, built in 1963 by the former owner. I have no idea what the internals are, but it does max out at about 86 on the Nevada desert, which would be 3766 rpm at that tire diameter.

bigdoor · 03-03-2022, 08:36 PM

I try to stay below 2700

woodiewagon46 · 03-04-2022, 10:32 AM

My Deuce roadster has a Ford 8" rear with 2.89 gears. I cruise down the Jersey or PA Turnpike at 70 MPH at about 2400 RPMs. I have a friend that's building a street rod with over 800 HP and 4.56 gears and monster Mickey Thompson's in the rear. He told me he can't wait to drive to the Nat's in Louisville. I don't think he has any idea what that is going to be like. Back to your situation, the only thing you can do is change the gears, which is a major job or tires, 3766 RPM's is a lot for a flathead. As most have suggested between 2300 and 2700 is a nice cruising RPM.

HDowse · 03-04-2022, 11:00 AM

Here's a good link to rpm, tire size, differential ratio and speed.
http://www.advanced-ev.com/Calculators/TireSize/

Lawson Cox · 03-04-2022, 01:38 PM

Run WIDE OPEN. It's a Ford.

Phil Gillespie · 03-04-2022, 01:55 PM

Quote:

Originally Posted by ford38v8

Well, assuming that 6.00 16 Cokers are 29" diameter ?, I did the math posted by woodiewagon46. My '38 Conv Cpe purrs at 70 mph, to my ears sounds and feels better than at 65. I have 3.78 gears, which puts my rpm at 3066. My engine is a 59L, built in 1963 by the former owner. I have no idea what the internals are, but it does max out at about 86 on the Nevada desert, which would be 3766 rpm at that tire diameter.

The above mirrors my 39 coupe tyre wise and rpm. Runs well at 70 mph.
Our speed limit here in NZ on open road is 100 kph. Usually run at 60 to 65 mph will run here sweet all day.
Phil NZ

Ol' Ron · 03-04-2022, 02:10 PM

Between 2000/2500 rpm air/fuel ratio in the low 15.
Gramps

V8COOPMAN · 03-04-2022, 02:54 PM

Quote:

Originally Posted by Lawson Cox

Run WIDE OPEN. It's a Ford.

Yeah, it's a Ford engine that exploded around itself while racing, or what's left of it, anyway! DD

J Franklin · 03-04-2022, 04:01 PM

What did that busted engine start out as?

V8COOPMAN · 03-04-2022, 05:08 PM

Quote:

Originally Posted by J Franklin

What did that busted engine start out as?

I saved that almost unbelievable picture years ago. I can't remember ANY details now, except that it was some sort of Ford race engine.

That picture is almost as good as the two pics below of the engine in the "Magic Muffler" Fiat at Lyons one night with Gary Essman driving. That crankshaft ended-up in another engine at a later date. DD

.

J Franklin · 03-04-2022, 06:20 PM

I,ve raced at Lions drag strip in S. Cal. Is that Lyons? I also used to work at San Fernando drag strip!

5851a · 03-04-2022, 06:22 PM

Quote:

Originally Posted by J Franklin

What did that busted engine start out as?

I don't know what it is either, but I would hit the buy again button on the cam manufacturer.

J Franklin · 03-04-2022, 06:33 PM

I once broke down on Sunset Blvd. one New Years eve in front of the Graumans Chinese theater. I had a box of pistons in the trunk from some other work and spread them out behind my car till I got it going. Lots of laughs that night!

tubman · 03-04-2022, 09:29 PM

That second picture is not a good commentary on "C&T Strokers".

34fivewindow · 03-04-2022, 09:58 PM

Quote:

Originally Posted by tubman

That second picture is not a good commentary on "C&T Strokers".

The funny thing about the Magic Muffler Fiat car. is the guy sitting in the drivers seat was actually the engine builder, and the first time behind the wheel. What you see is when someone forgot to torque the main caps

03-03-2022, 04:15 PM	#1
kingskid Member Join Date: Nov 2010 Location: Denver, NC Posts: 44	Cruise RPM? New to me: 47 Ford business coupe. It has 59AB with Offy heads,Offy intake 2 97's carbs, Isky 400 cam stock 3 speed trans. As far as I can tell stock rear diff. What would be a comfortable RPM on highway speed say 60-65?

03-03-2022, 04:20 PM	#2
51 MERC-CT Senior Member Join Date: May 2010 Location: East Hartford, Ct Posts: 5,898	Re: Cruise RPM? Need differential ratio and tire dia to give any meaningful figure. ( other than that 2500 ±) __________________ DON'T RECALL DOING SOMETHING FOR MYSELF BASED ON SOMEONE ELSE'S LIKES OR DISLIKES Last edited by 51 MERC-CT; 03-03-2022 at 04:42 PM.

03-03-2022, 04:38 PM	#3
40cpe Senior Member Join Date: May 2010 Location: Star, MS Posts: 4,024	Re: Cruise RPM? "Comfortable cruise RPM" is what it is regardless of other factors. My '38 has a 3.78 rear and 29" tires. 60 MPH is about 2700 rpm and the car and I am comfortable there.

03-03-2022, 06:06 PM	#4
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Re: Cruise RPM? I have 3.55's and 2.25/75R15 rear tires in my '51 club coupe with a '51 Merc with a stock cam, no overdrive. I find that 2700 RPM is the maximum comfortable cruise speed. On my car, that's about 70 MPH. I find these engines like to run at 2300-2700 RPM.

03-03-2022, 06:23 PM	#5
woodiewagon46 Senior Member Join Date: Jun 2012 Location: Long Island,NY Posts: 1,555	Re: Cruise RPM? R.P.M. equals, MPH times gear ratio, times 336, divided by the tire diameter. That will tell you what you have now.

03-03-2022, 08:15 PM	#6
ford38v8 Senior Member Join Date: Jul 2011 Location: SF Bay Area Posts: 6,646	Re: Cruise RPM? Sponsored Links (Register now to hide all advertisements) Well, assuming that 6.00 16 Cokers are 29" diameter ?, I did the math posted by woodiewagon46. My '38 Conv Cpe purrs at 70 mph, to my ears sounds and feels better than at 65. I have 3.78 gears, which puts my rpm at 3066. My engine is a 59L, built in 1963 by the former owner. I have no idea what the internals are, but it does max out at about 86 on the Nevada desert, which would be 3766 rpm at that tire diameter. __________________ Alan

03-03-2022, 08:36 PM	#7
bigdoor Member Join Date: Oct 2014 Location: peoria az. Posts: 38	Re: Cruise RPM? I try to stay below 2700

03-04-2022, 10:32 AM	#8
woodiewagon46 Senior Member Join Date: Jun 2012 Location: Long Island,NY Posts: 1,555	Re: Cruise RPM? My Deuce roadster has a Ford 8" rear with 2.89 gears. I cruise down the Jersey or PA Turnpike at 70 MPH at about 2400 RPMs. I have a friend that's building a street rod with over 800 HP and 4.56 gears and monster Mickey Thompson's in the rear. He told me he can't wait to drive to the Nat's in Louisville. I don't think he has any idea what that is going to be like. Back to your situation, the only thing you can do is change the gears, which is a major job or tires, 3766 RPM's is a lot for a flathead. As most have suggested between 2300 and 2700 is a nice cruising RPM.

03-04-2022, 11:00 AM	#9
HDowse Senior Member Join Date: May 2010 Location: Hancock, New Hampshire Posts: 375	Re: Cruise RPM? Here's a good link to rpm, tire size, differential ratio and speed. http://www.advanced-ev.com/Calculators/TireSize/

03-04-2022, 01:38 PM	#10
Lawson Cox Senior Member Join Date: May 2010 Location: Above the gnat line in Georgia Posts: 7,009	Re: Cruise RPM? Run WIDE OPEN. It's a Ford. __________________ Life is like a roll of toilet paper. The closer to the end, the faster it goes. It is better to be seen, than viewed. "We sleep safe in our beds because rough men stand ready in the night to visit violence on those who would do us harm".

03-04-2022, 02:10 PM	#12
Ol' Ron Senior Member Join Date: May 2010 Location: Chester Vt Posts: 8,860	Re: Cruise RPM? Between 2000/2500 rpm air/fuel ratio in the low 15. Gramps

03-04-2022, 04:01 PM	#14
J Franklin Senior Member Join Date: May 2010 Location: Oregon Posts: 5,963	Re: Cruise RPM? What did that busted engine start out as?

03-04-2022, 06:33 PM	#18
J Franklin Senior Member Join Date: May 2010 Location: Oregon Posts: 5,963	Re: Cruise RPM? I once broke down on Sunset Blvd. one New Years eve in front of the Graumans Chinese theater. I had a box of pistons in the trunk from some other work and spread them out behind my car till I got it going. Lots of laughs that night!

03-04-2022, 09:29 PM	#19
tubman Senior Member Join Date: Dec 2013 Location: Minnesota, Florida Keys Posts: 10,320	Re: Cruise RPM? That second picture is not a good commentary on "C&T Strokers".