What speed will I be able to get from a stock 1936 flathead?

[Bruce Lancaster]

To repeat, the Ford speeds spec was a TOP speed number to verify whether or not the car had as much power as it was supposed to have. It would not have been suggested as a normal speed...and in '34, most people would have had a hard time finding a road good enough to try 85!
The point was that id the customer complained about power, the Ford specified acceleration and speed trials would verify if the engine was up to snuff or needed work. Likewise the economy specs. 4,250 is kind of at the limits for a stocker, not for durability but because power drops dead right around there...

[Mike51Merc]

Originally Posted by 40 Deluxe

Buy or borrow a GPS unit, find a straight, level stretch of road, and have at it! Accurate, real-world, first-hand results!

Yeah, or a free speedometer app on your iPhone!

[linechaser32]

75 mph down a mine shaft.

[scooder]

What do you not believe? What Bruce has posted? Or that with a 4.11 rear, the car won't rev to 4250rpm in top?
I have the same info as Bruce, it is correct. If Ford were lying about the top speed, every Ford that could not do these speeds would have required work to make it able. And Henry wouldn't have liked to pocket for all this work.
What would this achieve?
Nobody has said that you can cruise along at this speed.
I have a test procedure from late 40's for testing valve spring strength. This included hitting 60mph in SECOND gear and if the valves started to flutter, you have weak springs. Car had 6.00x16 tyres and 4.11 rear.
As Bruce has pointed out, the top speed test is for a good condition engine. And it would've had the right ignition curve and such and is fitted with genuine parts of the correct spec, not a bunch of the crap repro parts being sold today.
Many,many folk would be surprised how well a stock flathead goes when it's all up to par.
Martin

[Straightpipes]

What's an app??

[Mart]

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It had to ATTAIN 84.5 mph, not be able to cruise at it for an extended period.

I get worried when anyone asks how fast an old car will go. If you really want an old car you will be happy to go at whatever speed the car is happy at. The speed it is happy at may be a long way short of the actual max speed attainable.

Mart.

[ken ct]

If you go out and drag race any old Honda Civic's you will lose. LOL ken ct.

[1929 Marmon]

For those looking for speed

stop run back and watch each tire
http://www.angelfire.com/ak2/intelli...t/pitstop.html

[41LjH]

@70 my modified 8BA is turning 3550RPM. This engine has turned 5500+, but I don't want to try it in third!
GPS speedometer cross checked with iPhone app.
Geared 3:78 original 39 top-loader. 2:225/75R16 on 18x8 rear wheels.
As others have indicated top speed is a function of gears and tires more than engine.
That being said I don't exceed 60 on the interstate. If you want top end get a quick change and play with the gearset.

[Bruce Lancaster]

My 3.78 geared '48 was my ride in college, back when typical Eastern speed limits ran up to 75. I was able to collect a magnificent album of speeding tickets from just about everywhere between new Orleans and northern Vermont.
I remember one cop, who had a number from his radar already, of course, actually ask me if the old heap would go that fast! I admitted that it would. I'd love to know what he would have said if I had denied it...

[41LjH]

sorry 16x8" wheels

[Bruce Lancaster]

Another thing to remember...a completely stock flathead has an excellent lower end and oiling system and lousy breathing. Without mods, power just starts going away a little after 4,000 RPM (I've never had a tach and rarely did the arithmetic to calculate revs... I'm going to Ford dyno curves to put a number on that point), meaning that it is pretty hard to damage a sound engine by over revving it. Kinda like a VW Beetle...

[banjoQ]

I find the results from this post both interesting and confusing. I have an 8BA in my truck, 39' top loader and 4:11s' in the back. I have been able to cruise it at about 45mph without the motor sounding like it's going to scatter. What will these motors comfortably do, RPM wise? I would like to keep up with highway traffic, but not at the risk of doing harm to a 63 year old motor. I have been told that I can drive it all day long, flat out. Really? Not that I would do such a thing but are they that tough? Currently I am thinking about changing the gears out back to 3:78s. Maybe I am being too gentle with the old boy, I dunno. But if I could get another 10 mph out of it I would be happy. Just curious.

[Kube]

Originally Posted by Tinker

Bruce is there a 3.25 gear set for early fords or is that a later gear set?

I have a NOS matched set of 3.26:1. I asked about these some time back and the opinions that made the most sense to me is these were experimental.
I have never been tempted to use them as I don't believe a stock flathead would have enough power to offer a decent performance.
Personally, I like the 3:78 sets the best. Good (enough) off the line and great high end without much stress on the engine.

[Kube]

Originally Posted by tubadon40

Keep in mind there was a BIG difference in gasoline formula back when those spec's were made and todays mixes.

If you try to match those specs I would use the premium at the pump and NO alcohol.

I can understand the NO alcohol but premium (high octane) would not effect mpg on a stock flathead.

[Dave D]

I can understand the NO alcohol but premium (high octane) would not effect mpg on a stock flathead.

Except to make it worse.

[scooder]

Originally Posted by banjoQ

I find the results from this post both interesting and confusing. I have an 8BA in my truck, 39' top loader and 4:11s' in the back. I have been able to cruise it at about 45mph without the motor sounding like it's going to scatter. What will these motors comfortably do, RPM wise? I would like to keep up with highway traffic, but not at the risk of doing harm to a 63 year old motor. I have been told that I can drive it all day long, flat out. Really? Not that I would do such a thing but are they that tough? Currently I am thinking about changing the gears out back to 3:78s. Maybe I am being too gentle with the old boy, I dunno. But if I could get another 10 mph out of it I would be happy. Just curious.

45 mph? Is that right, or a typo?
It should (with 4.11 rear) be fine at 70mph. I ran 4.11:1 in my old roadster with a warmed over flathead. With stock bottom end and oiling. I would cruise up the road at 70+ mph. That never hurt it. It will sound busy, if your used to modern stuff with its 97 speed trans. But you won't hurt it at highway speed.
Martin.

[Mike51Merc]

Originally Posted by scooder

45 mph? Is that right, or a typo?
It should (with 4.11 rear) be fine at 70mph. I ran 4.11:1 in my old roadster with a warmed over flathead. With stock bottom end and oiling. I would cruise up the road at 70+ mph. That never hurt it. It will sound busy, if your used to modern stuff with its 97 speed trans. But you won't hurt it at highway speed.
Martin.

70mph with a flathead with 4:11 gears and no overdrive is no fun at all.

[Mart]

banjoQ: You should be able to run at a comfortable 50 - 55mph all day. If you can't there is something wrong. Is your speedo reading slow?? Can you check it against another car or use gps??

Mart.

[scooder]

Originally Posted by Mike51Merc

70mph with a flathead with 4:11 gears and no overdrive is no fun at all.

That is matter of opinion, I have no problem doing this with my stuff. My daily Cortina had 3.9 gears and 165x13 tyres. Will cruise all day at circa 4000rpm at 70 mph. I really believe it's more to do with what your used too.
But 45 mph is ridiculously low , it ain't a Model A. That truck will be fine at 55 - 70 mph. It won't hurt it.
Martin.