Author Topic: Flathead V-8  (Read 170812 times)

Offline gbritnell

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Re: Flathead V-8
« Reply #285 on: March 25, 2015, 07:03:15 PM »
Hi Eric,
The problem with the head studs on the Ford flatheads came from the thin head deck above the water jackets. To get the exhaust through the water jacket the area above the exhaust runners needed to be as wide as possible and without much restriction so this thinned out the head deck. It would be almost impossible to find any old flathead without cracks from the head stud holes. With my exhaust exiting on the top of the block I don't have that problems so my head deck is thick enough to hold well.
gbritnell
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Offline petertha

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Re: Flathead V-8
« Reply #286 on: March 25, 2015, 08:09:31 PM »
The outside diameter was left heavy until the bore was finished and then it was turned to size - gbritnell
Hmm.. another good point to ask some questions. On my liner prototype (not knowing better) I did the OD turning first figuring A) if I messed up that OD dimension/finish, at least I didn't also lose the more lengthy boring work too B) I was concerned about distorting or egging the liner circularity by the cutting tool 'pushing on' the OD when it was a thin shell. Q1 - Sounds like your preference is the opposite: leave the wall thickness meat on until boring is done for less vibration & dimensioning? And maybe cutting outside ->in or inside -> out is just tit-for-tat from distortion standpoint?

Q2- In my case I have to arrive at finished (0.945") bore size + finish because I'm using commercial RC rings. After boring I ran a reamer for cleanup/circularity, took maybe 0.003" off. That aspect worked well & somewhat minimized hitting exact dimension with boring bar alone. But because of reamer size, it left it about 0.006" under target size. I figured that's fine, would allow me some mistake tolerance. What I hadn't counted on was how long it takes to lap that amount off. I have the same lapping tool as you show, but 400 & 320 was very slow. After maybe 10 min on the lathe I'd take off 0.0005". The finish was great but a long ways off final dimension. I have some 220 coming, but now suspect this mode is a waste of time & I should just bore to within say 0.003" or so. Can you elaborate on your target dimensions & lapping grit strategy?

Offline Tennessee Whiskey

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Re: Flathead V-8
« Reply #287 on: March 25, 2015, 11:05:26 PM »
Thanks for the explanation George.  Dad said the old saying was if it got hotter than your girlfriend, you were in trouble.  Love the old flathead,  if I was building a show car,  it'd be a flathead  :naughty:

E

Offline gbritnell

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Re: Flathead V-8
« Reply #288 on: March 26, 2015, 02:12:52 AM »
Hi Peter,
I have always found that boring any kind of hole in a thin walled section produces a chatter so that's why I adopted the procedure that I use. I try to leave the wall as heavy as possible so that my boring operation is nice and smooth. My finish bore diameter is .832. I bored the holes to .831. I tried for .0005 press fit into the block. I might be a tenth or two off of that dimension but that's what I was shooting for. I'll be using Loctite with that. Even with a .0005 press fit I find that it will still collapse the wall a slight amount, maybe .0007 on the diameter so now I have the initial .001 that I left plus anywhere from .0007 to .001 more. This leaves me around .002 to hone. I set my hone so that it will slip into all the bores with a little clearance for the lapping compound. I spin the hone at a slow speed 200 rpm and work it back and forth in each hole until I no longer feel any resistance, or very little resistance. I then adjust the hone ever so slightly and redo each bore. I use a medium grade honing paste. The idea is to get each cylinder the same size. Once I feel that I have achieved this I wash out all the grit with solvent and take measurements. As you mentioned you can hone for quite awhile and not take much stock off. At this point if I have a cylinder or two that's a little off I will work them until they match the others. Once I have everything equal I then wipe off the hone and apply a very fine paste. I then take only a few passes in each bore just to give a nice smooth finish. Not shiny smooth but not dark grey looking from the coarser paste.
The one thing that I have going for me is that whatever I end up with I make the rings and pistons to fit. With using commercial rings you have to be a little more careful but I don't think I would leave more than .002 for honing. Even if you end up at +.0005 or -.0005 the rings will still seal. The main thing is to get the bores round and straight.
As a side note once I have the bore turned I jam a wadded up paper towel into the bore. This minimizes the chatter while turning the O.D. My finished walls are only .05 and I got no chatter on the O.D.
gbritnell
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Offline gbritnell

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Re: Flathead V-8
« Reply #289 on: March 31, 2015, 02:31:38 AM »
Sometimes what seems like it should be simple or maybe not as hard turns out to be a real problem. In designing the engine I followed the full size engine in regard to the various helical gears that were used. Having made the Chuck Fellow's fixture to cut the helical gears for my Ford 300 six I figured it wouldn't be a big deal to make them for this engine. I think part of the problem is the pitch of the 300 gears was much finer, about 56 D.P. as I recall compared to 40 on this engine.

I made the first cutter by grinding a high speed blank to the required radius and cutting it from W-1 drill rod. In cutting it I went to my numbers but it turns out that the width of the root came out to wide. I should have checked it when I cut it but I relied on my numbers. When I made the gears for the 300 six the first thing I did was cut a pair of spur gears to check the mesh. When I cut the spur gears with this 40 D.P. tool it left the teeth too narrow. At this point I checked the width of the cutter and found it to be .005 too wide. This doesn't sound like a lot but when you cut two gears you end up with .010 lash between the mating pair.

Rather than annealing this cutter and knowing that it would be hard to make an intermittent cut across the flutes I just made another cutter. This time I checked before removing it from the lathe. I turned up another set of blanks and cut a second pair of spur gears. This time they came out very well.
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Offline gbritnell

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Re: Flathead V-8
« Reply #290 on: March 31, 2015, 02:38:54 AM »
With the glow of success at hand I set about making the necessary new parts for the Chuck Fellow's fixture, a new index wheel and a couple of helical templates, one for a right hand and one for a left.
When I  saw what Chuck had used for his helical template, a piece of .125 aluminum as I remember, and knowing how hard it is to bend it into a 1.00 diameter I opted for a piece of .032 brass. I cut the template out and then set it up on my sine plate to check the angle. With a little filing I got it spot on. The next step was to anneal it to easy the bending. The template was then formed around a piece of 1.00 stock.
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Offline gbritnell

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Re: Flathead V-8
« Reply #291 on: March 31, 2015, 02:48:27 AM »
Two locations were marked for the mounting screws and using a small ball ended burr in my Dremel I ground the holes into the helical template. These were then finished up with a file. The new index wheel and template were installed on the fixture and some blanks were made to cut the gears from. For the distributor the gear on the cam will be steel and the other brass. For the oil pump drive there will be 2 steel and one brass.

I set the fixture into the vise and aligned it using a 45 degree tool makers triangle. The first blank was inserted and locked down with the set screw. The hardest part in cutting helicals is getting the cutter right on the center of the stock. Too high or too low from center makes an irregular tooth.

To cut the brass gear I made three passes but for the steel one I had to go with four.
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Offline gbritnell

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Re: Flathead V-8
« Reply #292 on: March 31, 2015, 03:00:38 AM »
When I got the first pair cut I needed to check them for the proper mesh and center spacing so I dug out my checking fixture. It's just a small angular block with a bushed hole in one side and a slot on the other side for a moveable bushing. This way I can make bushings for different shaft sizes. The gears were brought into mesh, the moveable bush was tightened, the gears were removed and then using a DTI and a height gauge I checked the distance. With the gears in the proper mesh the center distance was .005 to close so I set that pair of gears aside and made up 2 new blanks. For 40 D.P. the total infeed is .054 which I had used for the first set. For the second set I only went in .052. The blanks were then put into the lathe and the proper width gear was parted off. This pair was then mounted in the fixture for checking. This time the mesh was within .002 and the profile looked pretty good.
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Offline gbritnell

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Re: Flathead V-8
« Reply #293 on: March 31, 2015, 03:06:08 AM »
That takes care of the distributor end and the gear for the top of the oil pump. The remaining 2 gears to drive the oil pump will need new helical templates, one for a left hand helix and one for the larger diameter intermediate gear.
At this point it's too late to change the engine design but had I to do over I would have forgone trying to replicate the full sized engine and just made a simpler setup to drive the oil pump.
gbritnell
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Offline Don1966

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Re: Flathead V-8
« Reply #294 on: March 31, 2015, 03:27:34 AM »
George I would say you did a dam good job making those gears. Truly inspirational bud and I like............ :praise2:

Don

Offline gbritnell

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Re: Flathead V-8
« Reply #295 on: March 31, 2015, 10:45:07 PM »
One last gear to make, the intermediate gear for the oil pump drive. This would require another cutter and helical template.
To calculate the proper cutter for a given helical gear there is a mathematical formula based on the number of teeth on the gear and the helical angle. This gear has 22 teeth but when the profile of the cutter is calculated it's for a 60 tooth gear. Using Don's spread sheet for calculating the required numbers I ground up a .375 high speed lathe tool with a .349 diameter ball on the end. The cutter was made from W-1 drill rod, hardened and tempered. 
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Offline gbritnell

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Re: Flathead V-8
« Reply #296 on: March 31, 2015, 10:54:53 PM »
I could just barely use the helical gear cutting fixture the way that it was built because the template for this gear is 37.3 degrees and it had to be modified to allow enough travel to cut the gear.
As shown previously I cut a piece of .032 brass and made the template. It was mounted on the fixture along with a blank for the gear.
I cut the first gear and when I was finished I had a close look at it and saw small steps on one side of the tooth profile. The number of steps matched the number of cuts I made to go to the proper depth.
It almost looks like something was flexing with each cut but the cutter is quite rigid and I can't imagine the fixture shaft is flexing enough to do this so I'm kind of at a loss. In the photos you can see the small steps.
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Offline gbritnell

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Re: Flathead V-8
« Reply #297 on: March 31, 2015, 11:00:20 PM »
The cutter was cutting the brass quite easily and I was conventional cutting so for the next blank I figured I would go to full depth on one pass. (.054) When I got finished I examined the gear and it looked great so with the mesh issues I had with the smaller gears and everything already set up I cut another gear but this time only went to .051. I don't have a setup made to check the center distances yet but I assume between the 2 gears I should be able to make them work.
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Offline gbritnell

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Re: Flathead V-8
« Reply #298 on: March 31, 2015, 11:04:10 PM »
This last photo shows the gear train to drive the oil pump. The small right hand helical gear mounts on the end of the camshaft. It drives the left hand intermediate gear and it drives the oil pump.
Boy I'm sure glad this part of the project is done!
gbritnell
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Offline gbritnell

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Re: Flathead V-8
« Reply #299 on: March 31, 2015, 11:17:44 PM »
I would like to take this opportunity to thank the following people, without whom this project would have taken a different turn. First to Chuck Fellows for devising this fixture and the initial calculations to make helical gears. Next would be to Marv Klotz for his wonderful array of quick calculation programs and especially the follow up program for cutting these gears. If you haven't done so already I suggest downloading a few of Marv's programs, they are extremely helpful. And last but not least is Don for his spread sheet to calculate the button dimensions for cutting spur gears.
gbritnell
Talent unshared is talent wasted.

 

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