Flathead Ford Asymmetrical - why?

Why did old Henry design and build his flathead asymmetrically?

 

looks pretty symetrical to me... They're not symetrical fore and aft to make the crank pins line up with the piston bores.

 

I remember seeing that way back when I was a kid reading Floyd Clymers V-8 book, I don't recall there being an explanation about the cam being offset and valves being set on different angles.

Maybe an ***embly line issue?

 

It was the theory of that time, that it would minimize piston wear, if i remember right.

 

I don't know what you're seeing but the cam looks pretty damn. centered to me and the valves are symmetrical. What you may think is the valve angle they are showing on the left bank is really the spark plug. They don't even show the valves on the left bank. But that's just how I see it.

 

I remember reading this about offset wrist pins......

 

Try reading the dimensions. That .265 under the oilpan is how far off center the cam is. One bank of valves is 49.36°, the other is 52°.

 

No offset wrist pins. A frencman named DeSaxe found out that if the piston was offset from the crank the engine ran smoother and actually produced more crank degrees on the intake stroke. The cylinder centerlines are offset in a clockwise direction by 0.1875" from the crank centerline. Henry must have liked the idea.

The valve angles were different on each side until around 1945 when the 41A and 59A blocks were produced and were 50*'s each side.

Here's a CAD drawing I made to show the effect of the offset:



I have to thank Bruce Lancaster for telling me about the book this info came from (noted on drawing). Book was written by Ford engineers in England.

Jim

 

Does it really matter ? Many still goin strong after this many years,why question it?

 

The DeSaxe principle reduces wear on things like cam and crank bearings etc.

Another side effect is reduced parasitic losses, Less drag = more hp.
Although the difference in hp is very minimal it still exists, the important design factor behind the DeSaxe principle is that it helps to remove some parasitic drag and thus engine bearings (etc) last longer.

Make Sense?

 

If you question things you learn. And can use that knowledge to build other engines that will be going strong for many years after.

 

Thanks to Jim for the drawing and explanation, and thanks to Moe - it makes sense to me.

I haven't been able to find a copy of the English Ford book - would it be possible to post a copy of the relevant piece from the book?

Thanks again,
Neil.

 

The offset reduces piston slap. If you ever swapped the pistons round the other way on a SBC, to get a bit more HP, you'd know that! Cold starts become a tooth-jarring clatter.
Many aluminum heads have different volumes, L to R, to compensate for the valve angles being different. I think 8BA heads were made that way, too.

 

I think the pre 1945 heads had different pockets in the heads left to right and the post '45's had the same pockets until 1948 (in trucks) and 1949 (in cars). Pre 45 blocks would be 18, 40, 68, 77, 81A, 81T, 99T & 29A blocks.

**-6049 was right head part # & **-6050 was left head. Spec sheet I have from Ford lists 8BA-6049C and 8BA-6050C as 6.8:1 CR and 73 to 75 CC's pocket size. The 8RT heads list the same CR & pocket size. Of course these heads had the water outlets at the front and the dizzy hold down on the p***enger side so they had to be mounted on the engine on the correct side.

Jim

 

Got a full-size of this beauty?

 

Instead of spouting subtle put-downs, you might try taking your own advice. The 49.36* is actually the spark plug location and the cam is only .0342 (?, hard to read on that small diagram) offset.

 

I believe the cam offset is 0.0242" thunderbirdesq from the ford drawings.

 

Craigtone, you can do the right click and save as and it blows up pretty good on your computer in one of the photo tweaking programs. That would make a nice print to frame for the "car room".

 

You have to read about Henry Ford to see what drove him. He was not as practical as he was hard headed. He was also miserly. He didn't like to spend a penny more than he had to. He really wanted to build the X block engine in 1932 but his son Edsel talked him out of it. The X-block was not in any way practical. The engineers that designed the Ford L-head 45 degree V8 had a lot of hurdles to overcome. The DeSaxe principal was a good idea for more than one reason. More power and more reliability meant less warranty problems. Henry did not want to lose one customer due to reliability problems so the offset made sense to him. They must have had a reason to locate the camshaft in a near centerline over the crankshaft. It may have been for clearance issues, drive issues, or block manufacturing issues but for what ever reason, it caused the offset in valve angles that exist in all of the Ford L-head V8s. The post war engines were changed slightly but not by much. They were still offset.

 

The text gets unreadable ...

 

I found the diagram in a "1932-38 Ford Factory Shop Manual" from Detroit Iron Information Systems. Unfortunately the CD-ROM uses PaperPort so I cannot save an image to my computer except by printing, then scanning into Paint, then converting in Photoshop to a JPEG file. Whew!
But here it is - I hope it is better definition than the first and lets you see that the centre line of the valves in the right bank (left in the diagram) coincides with the top of the spark plug.

Thanks for the steer to addall.com - I've ordered a copy of the book.

A little research via the trusty Google leads me to believe that Count De Saxe was the patron of Nicholas Cugnot who invented the first steam-powered vehicle in 1765, and to whom the credit may be due?
http://youautomobile.com/index.php/automobile-biographies/nicholas-joseph-cugnot/

Onwards and upwards,
Neil.

 

That bigger diagram helps! You are correct, and I suppose Relic Stew is correct that the cam is .265" from the block centerline.

 

WRONG!
It appears that the principle has nothing to do with anyone called De Saxe, but derives from the French word "desaxé" meaning offset or unbalanced and has been employed since before WW1. Far from falling into disuse, it seems that the principle is alive and well and in use in modern machinery by Honda, Yamaha and Hyundai a**** others.

 

looking at the image, I have to say that the 49.36 and the 52.09 is in fact the angle of the valves. You can follow the lines in the image all the way down to the camshaft which runs right through the centerline of the valves

 

Bringing this back up . . .
I've put the dimensions shown in the diagram into a parametric CAD model - they cannot be correct. Given this, I'm not exactly sure WHAT the true offsets and centerlines really are - not an easy thing to measure. What I do know is that the valve angles on my 1942 Merc do match the drawing - which I can see no possible way for this to occur unless the camshaft is not on the same centerline as the crankshaft. Given the deck heights, rod lengths and valve lengths are the same on both sides - then the cam has to be moved. The mystery deepens . . .

 

...I think some of you guys have waaay too much free time on your hands....

.

 

what has bothered me more is why there is only 6 exhaust ports for 8 cylinders.

 

LMFAO Olds did the same thing on the early valve in heads, well actually the center ports were Siamese but I have seen some of the very early heads without a divider.

 

I think Henry decided the block was long enough . . . and he wanted to save on cast iron!

 

Look again mate!
The crank and cam are only offset 0.0242. [24 thou]
Whereas the Bores which are still at 90° are offset to the centreline off the crank by .168"
This is a common practice today with offset pistons
Whereas back then Ford was the "King of M*** Production", so they did the offset in the casting /machining process .
Offset pistons sometimes require Left and Right hand configuration