What’s up with this mercury crank gear (backwards?)

[busmania]

The teeth on this mercury crank gear seem to be cut the opposite way. No it’s not on backwards. No matter which way I put my cam gear on it, it doesn’t line up. Photo is next to my original crank and gear (mercury on left/bottom of photo, Ford on right). Even my machine shop is scratching his head when I took it to him today to remove the gears. What gives?

8CAFBCEC-7C22-4303-95EA-1814262E6A54.jpg

[petehoovie]

Originally Posted by busmania

The teeth on this mercury crank gear seem to be cut the opposite way. No it’s not on backwards. No matter which way I put my cam gear on it, it doesn’t line up. Photo is next to my original crank and gear (mercury on left/bottom of photo, Ford on right). Even my machine shop is scratching his head when I took it to him today to remove the gears. What gives?

Attachment 524056

[Ggmac]

Early and late . Early meaning non 8ba .

[38 coupe]

Ford reversed the tooth cut direction when they went to the 8BA family of flathead V8s. 32-48 motors are one way, 49-53 motors are the other way. For use in an early motor use the earlier gear set.

[Newc]

Cam thrust is reversed, 8ba VS 59 ab type. Also be aware of oiling to front of cam. Newc

[Ronnieroadster]

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Originally Posted by Newc

Cam thrust is reversed, 8ba VS 59 ab type. Also be aware of oiling to front of cam. Newc

The cam thrust thus gear pitch angle direction is different on the 48 and earlier gears the cam thrust for the early gear is towards the front face of the block compared to the latter 8BA which has the gear pitch angle the opposite from the early gear which now thrust the cam towards the front cover. However once the oil pump intermediate 2 to 1 ratio gear is installed and once the oil pump is driven by the cam the early cam is now pushing forward into the front cover the rear cam gear pitch is the same on all flatheads.
During my research for reduced internal friction for my record setting Ford flathead engine's I was surprised when I discovered the above during my friction measuring experiments. Just some information for anyone like me trying to think outside the box.
Ronnieroadster

[alchemy]

So Ronnie, it makes no difference which crank and cam gears are used, the cam will be pushed forward anyway by the rear gears?

[Bored&Stroked]

Part of what needs to be considered is what prevents "cam walk" and tunes the thrust measurement. The answer is the timing cover. On 49-53 engines, the end of the cam snout rubs on the timing cover - on 32 - 48 engines, the cam gear itself rubs on the timing cover. It is critical to check your end-play - it should be around .004 to .008. Keep in mind that the thickness of the timing cover gasket can come into play. The original Ford gaskets were pretty thin - about .008, some of the aftermarket gaskets are .015 . . . which just increased your end-play by .007. Having extra end-play means that the cam timing and distributor timing fluctuates more than if you only had .004.

So, check your camshaft end-play no matter what gears you run and also measure your timing cover gaskets to see how thick they are.

Just a few tips . . . hoping this helps some of you.

Me: I run the early aluminum timing gear sets - with the early crank gear - regardless of year.

[Pete]

If you run a dry sump oil pump and straight cut cam drive gears, the cam floats fore and aft.
Less friction. Good for 30 hp.

[Bored&Stroked]

Originally Posted by Pete

If you run a dry sump oil pump and straight cut cam drive gears, the cam floats fore and aft.
Less friction. Good for 30 hp.

That makes sense. Where did you happen to get straight cut gears for these engines? Custom made? Or, is there something that works or can be modified to work? I wonder if Torrington bearings would help?

[Pete]

Originally Posted by Bored&Stroked

That makes sense. Where did you happen to get straight cut gears for these engines? Custom made? Or, is there something that works or can be modified to work? I wonder if Torrington bearings would help?

Dan McEachern on this and the model A forums makes them.

I would not trust Torrington's in that application.

[Ronnieroadster]

Originally Posted by alchemy

So Ronnie, it makes no difference which crank and cam gears are used, the cam will be pushed forward anyway by the rear gears?

Yes that's what I discovered surprising myself upon the discovery.

As Dale wrote the cam movement will effect the ignition timing on the latter flatheads 8BA versions. A few degrees of timing change will be noticeable if the cam is allowed to move to much. Checking the cam end play is something not many will do but its worth the effort and simple to do prior to assembling the valve train in the block.

Also as Pete wrote above straight cut gears eliminate this issue and I can say for certain that's the best way to go if your interested in building a record setting Ford flathead.
Ronnieroadster

[Bored&Stroked]

Thanks for the tip on Dan McEachern . . . I will have to see what he has - I'm definitely interested. Pete/Ronnie - do you guys have any contact information for me to look him up?

[38 coupe]

Not sure if this is current or not, contact info for Dan McEachern:
https://www.hotforhotfours.com/adver....htm#mceachern

[Bored&Stroked]

Thanks for the post - looks like exactly who I'm looking for!

[john in illinois]

He also makes excellent bronze cam gears and steel crank gears for all early Fords. T though flathead,

John

[busmania]

Woah, some great info in this thread! And I feel like I’m talking with some legends of this hobby.

Can we confirm my set up is ok?
Early cam
Early cam cover
Early gears
Early block

I don’t need to do anything g special do I? I remember reading about spacers and such with later cams?

[38 coupe]

Your combination of parts should be good to go. As mentioned by others a quick check on cam movement if you have the valves and lifters out isn't a bad idea.


The only caution I have is I prefer to use an aluminum cam gear instead of a fiber gear. Many people run fiber gears with no issues, but every now and then I run into someone who has a fiber gear fail.


Bored&Stroked posted a nice write up of checking cam movement here (the whole build thread is long and very worth reading):
https://www.jalopyjournal.com/forum/...#post-10905051

[busmania]

Thanks. I am using an aluminum cam gear too.

What’s the spec of the cam movement?

[38 coupe]

Bored&Stroked thread gave the following guidance: "I like to have the end-play somewhere between about .006 to .010 . . . you can probably get away with a bit more, but this is my goal. I put a dial indicator on the front of the cam - it was at .007, works for me. If I needed to "tune it", there are a variety of ways . . . thinner/thicker timing cover gaskets, machining the thrust surface on the cam or cover, etc.."