The Ford Barn

SofaKing · 04-05-2017, 09:08 PM

I have no basis for comparison so I am hoping folks can share their experience with similarly powered vehicles. I have a 39pu with a 36 Tudor drivetrain, 21 stud engine, 3 speed, 3.7x rearend, 26.5" dia tires. Engine is single carb, stock everything, no tach. How fast are you able to cruise with similar drivetrains?

drolston · 04-05-2017, 09:55 PM

Your ears and seat of your pants will tell you when the engine is spun up and the truck is near lift off. I suspect that will be at about 3000 rpm. Do the math. With those rear end gears and tires, you generate .021 mph per rpm. So if you are willing to cruise at 3000 rpm in high gear, you will be going 63 mph. And unless you upgrade the brakes, that is about as fast as you want to go.

I am going to put 3.54 gears and Lincoln (Bendix) brakes in my '41 coupe, so I can at least not be a hazard to interstate traffic doing 75.

Kurt in NJ · 04-06-2017, 06:55 AM

I would run the 39 with 60hp,4:44 rear, stock up the parkway at 70---all day, top speed was 74 (65-70, little over 20 mpg, 50-60,25+mpg)
the 46 big truck I tried to keep under 60 loaded, it got sold to a guy that drove it to california in 4 days--I think he drove it faster (15-18 mpg)

The quality of the chassis restoration will probably determine your comfortable cruising speed, the engine should make 75mph easy

Adam/Mill Valley CA · 04-06-2017, 07:36 AM

My '36 pickup with 21 stud motor(poured bearings), 3.78 rear and 6x16" tires cruises easily between 58 and 62 mph (GPS speed verified). It will do 70-75 no problem, but with stock suspension and even with Lincoln-Bendix hydraulic brakes (on the front) I don't feel comfortable at the higher speeds. I mostly stick to the far right lane and get passed a lot, but that's fine with me.Since I'm in the SF Bay Area I'm on the freeway very often, of necessity.Safety is always an issue with these old vehicles (which is to say, there isn't any). Kinetic energy rises dramatically with velocity.

Adam

SofaKing · 04-06-2017, 08:01 AM

Thanks, sounds like I am in the ballpark. I am tweaking the distributor and having an idea of real world performance is what I need. Power was dropping off at 53-55MPH so I turned the brake on my crab in one turn and find it'll do 70MPH though it feels like it's all in there. I am going to tweak a little more but it seems like 60 should be sustainable long term. I would be comfortable at 60-70, tracks straight, no wobbles, nearly hands free braking, all good except for the bump-steer issue.

40cpe · 04-06-2017, 08:38 AM

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600x16 tires I think were the norm for those trucks. Coker says a 600x16 is 28.3" diameter. You are loosing 5-6 percent with your tires. Upgrading the rear tires to 28" or larger would reduce the engine speed significantly.

SofaKing · 04-06-2017, 11:28 AM

Quote:

Originally Posted by 40cpe

600x16 tires I think were the norm for those trucks. Coker says a 600x16 is 28.3" diameter. You are loosing 5-6 percent with your tires. Upgrading the rear tires to 28" or larger would reduce the engine speed significantly.

Thanks, thought about that but not ready to drop $1200 for tires right now.

Seth Swoboda · 04-06-2017, 01:16 PM

My 39 pickup has a fresh 59A engine, 600x16 tires, 3:78 rear, the entire truck and drive line is in stock form. I have done 75 mph but I like to drive about 55-60 mph on the state highways. It seems to do just fine there.

04-05-2017, 09:08 PM	#1
SofaKing Senior Member Join Date: Jun 2014 Location: Salt Lake City, Utah Posts: 756	Performance reality check I have no basis for comparison so I am hoping folks can share their experience with similarly powered vehicles. I have a 39pu with a 36 Tudor drivetrain, 21 stud engine, 3 speed, 3.7x rearend, 26.5" dia tires. Engine is single carb, stock everything, no tach. How fast are you able to cruise with similar drivetrains?

04-05-2017, 09:55 PM	#2
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,627	Re: Performance reality check Your ears and seat of your pants will tell you when the engine is spun up and the truck is near lift off. I suspect that will be at about 3000 rpm. Do the math. With those rear end gears and tires, you generate .021 mph per rpm. So if you are willing to cruise at 3000 rpm in high gear, you will be going 63 mph. And unless you upgrade the brakes, that is about as fast as you want to go. I am going to put 3.54 gears and Lincoln (Bendix) brakes in my '41 coupe, so I can at least not be a hazard to interstate traffic doing 75.

04-06-2017, 06:55 AM	#3
Kurt in NJ Senior Member Join Date: May 2010 Location: on the Littlefield Posts: 6,159	Re: Performance reality check I would run the 39 with 60hp,4:44 rear, stock up the parkway at 70---all day, top speed was 74 (65-70, little over 20 mpg, 50-60,25+mpg) the 46 big truck I tried to keep under 60 loaded, it got sold to a guy that drove it to california in 4 days--I think he drove it faster (15-18 mpg) The quality of the chassis restoration will probably determine your comfortable cruising speed, the engine should make 75mph easy

04-06-2017, 07:36 AM	#4
Adam/Mill Valley CA Senior Member Join Date: May 2010 Location: Mill Valley,CA Posts: 275	Re: Performance reality check My '36 pickup with 21 stud motor(poured bearings), 3.78 rear and 6x16" tires cruises easily between 58 and 62 mph (GPS speed verified). It will do 70-75 no problem, but with stock suspension and even with Lincoln-Bendix hydraulic brakes (on the front) I don't feel comfortable at the higher speeds. I mostly stick to the far right lane and get passed a lot, but that's fine with me.Since I'm in the SF Bay Area I'm on the freeway very often, of necessity.Safety is always an issue with these old vehicles (which is to say, there isn't any). Kinetic energy rises dramatically with velocity. Adam __________________ 1936 pickup, stock, black 1965 Mustang coupe 289/4bbl, black/red 1971 Alfa Romeo GTV 1750 coupe, dark red/tan 1970 911E 2.2 litre dark blue/black 1968 BMW R50/2 US, black (m'cycle) 1967 Triumph TR6R , sea foam/cream (m'cycle) 2022 Royal Enfield Interceptor 650 red (m'cycle) 1974 Honda CB750 red (m'cycle) 2000 Kawasaki W650 blue/silver (m'cycle)

04-06-2017, 08:01 AM	#5
SofaKing Senior Member Join Date: Jun 2014 Location: Salt Lake City, Utah Posts: 756	Re: Performance reality check Thanks, sounds like I am in the ballpark. I am tweaking the distributor and having an idea of real world performance is what I need. Power was dropping off at 53-55MPH so I turned the brake on my crab in one turn and find it'll do 70MPH though it feels like it's all in there. I am going to tweak a little more but it seems like 60 should be sustainable long term. I would be comfortable at 60-70, tracks straight, no wobbles, nearly hands free braking, all good except for the bump-steer issue.

04-06-2017, 08:38 AM	#6
40cpe Senior Member Join Date: May 2010 Location: Star, MS Posts: 4,024	Re: Performance reality check Sponsored Links (Register now to hide all advertisements) 600x16 tires I think were the norm for those trucks. Coker says a 600x16 is 28.3" diameter. You are loosing 5-6 percent with your tires. Upgrading the rear tires to 28" or larger would reduce the engine speed significantly.

04-06-2017, 01:16 PM	#8
Seth Swoboda Senior Member Join Date: May 2010 Location: Southern Illinois Posts: 3,795	Re: Performance reality check My 39 pickup has a fresh 59A engine, 600x16 tires, 3:78 rear, the entire truck and drive line is in stock form. I have done 75 mph but I like to drive about 55-60 mph on the state highways. It seems to do just fine there.