Ford or Merc 49-53 engine ?

[woodburnranch]

Thanks for all the info. I'm betting its a Ford with the "Strato Star V8" logo and no other Mercury indications and will proceed accordingly.

[lefty rodan]

I'm no expert but I've had at least 15 4" merc cranks and the surefire method of determining size in my experience is to remove the pan and measure the width of the counterweights---six inches or more in width and it's a merc. Also measure the diameter of the sludge traps--5/8 " and it's usually a merc though I've had two Canadian merc cranks with the ford 3/8" diameter. Tim Ayres and I shared some merc cranks years ago and if memory serves correct both also had a raised casting dimple on the counterweights that apparently was peculiar to the Canadian variety of 4" cranks. Lefty Rodan

[Ross F-1]

Originally Posted by 19Fordy

Check the cover on the oil pump idler gear to see if it has a Merc part #on it. This one is cast iron, off a 51 Merc.

Why on earth would there be a Merc-specific cover? There's no difference in them back there, is there??

[quickchange34]

There is no difference in the covers, most are cast and some of the later ones were stamped steel. There is no cover just for merc.

[flatjack9]

There definitely is a cover with a Merc part number cast in it.

[rotorwrench]

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It must have been in the early stages of development in 38/39. I've seen the pics of the transmission cases with the 99A prefix so nothing would surprise me much. My later mid century cars both have the generic stamped cover of the 8BA family. A photo would be good though.

[Jefscoupe]

My local guru suggested to me to get the Scat crank kit from Speedway.
Pick your bore & stroke and you get crank, H-beam rods, pistons (all forged) rod bearings and rings.
All new and balanced ready to install.
For about $1800. He said he can't buy the same parts and prep a crank and balance it all for that.
Main bearings sold seperately depending on early or late block.
He tells me this after I've tracked down the original stuff.

[Flatkid8]

I don't see how in the world you could accurately measure stroke through #1 plug hole of a Flathead. I have 2 complete Mercs in the garage (1 pulled from a 53 and the other from a 50) and I will test the myth today and report back with a confirm or bust. Perhaps it would be possible with aftermarket heads if the plug hole is positioned slightly different, but im anticipating this test with stock heads to be impossible.

Dennis

[Ross F-1]

I can't imagine it being accurate, but I bet it can be done.

[rotorwrench]

A person can use a tye strap to find TDC since the big end can be pushed in there to block the piston from going any further up then rotate the assembly back around to the other side till the piston stops again & mark the crank pulley at both stops. Find center between stops and that is a relatively accurate measure of TDC unless the tye strap flips on its side during one of the top outs but I don't think it will as long as the part that is outside the cylinder remains flat against something. Other than barely being able to tell if the valves are opening/closing, that's about all you can do with the heads on there. The only other way would be by volume but you would have to know whether it was ever bored oversize or not plus the fluid would probably run past the worn out rings anyway.

Pull the head & measure the stroke if the assembly still rotates or pull the pan and measure across the crank counterweight cheeks as was already mentioned.

[19Fordy]

Originally Posted by Ross F-1

Why on earth would there be a Merc-specific cover? There's no difference in them back there, is there??

My thinking is that if the engine still has that green Merc oil pump idler gear cover with the same part #, it may be a 1951 Merc engine instead of a Ford since that is a part that would normally NOT have been changed on an original Merc engine. Therefore, it might be a clue that the engine in question is a Merc. Yes, stamped steel covers were made also. In fact, the Mercury Manual shown) gives a pictorial of the CM oil pump idler gear cover. It is shown as being made of stamped steel. No part # is on it. It would be interesting to see if there are any differences in the idler oil gear components since the internal depth dimensions of the cast cover and steel cover are different. Anyone know? Such info.may be helpful to the "purist" who is building a 100 point restoration and also wants the parts that you don't see to be 100% original.

[19Fordy]

Originally Posted by Jefscoupe

My local guru suggested to me to get the Scat crank kit from Speedway.
Pick your bore & stroke and you get crank, H-beam rods, pistons (all forged) rod bearings and rings.
All new and balanced ready to install.
For about $1800. He said he can't buy the same parts and prep a crank and balance it all for that.
Main bearings sold seperately depending on early or late block.
He tells me this after I've tracked down the original stuff.

I wonder if you have to "re-balance" those SCAT cranks?

[JM 35 Sedan]

Originally Posted by 19Fordy

I wonder if you have to "re-balance" those SCAT cranks?

I did have to balance mine when I put a 4-1/8" SCAT crankshaft in a 59, 284 ci engine that I built six years ago. The balance was way off. Maybe they have improved there manufacturing methods since then, but being made in China...who knows. One of the well known engine builders on the West Coast claims he does not need to balance them

[rotorwrench]

I noticed that the part number was 1CM on that cover. Most of the 1CM part changes had something to do with the Merc-O-Matic. That big torque converter may have worried them some. The other cast covers I've seen were mostly in trucks but they didn't have the mercury part number as I recall. Both of my Mercury cars are 51s but both are early and they have the early type manual shift with overdrive. The later parts book lists that cover for 51 to 53 Mercury cars.

A lot of aftermarket crankshaft manufacturers were concerned to make a part that could be balanced by removal of material instead of adding weight. Most folks that I've seen comment about these cranks mention that they had to remove a fair amount of metal to get them to balance. A lot depends on the weight of the rods & pistons used so one size doesn't fit all in that respect with all the different parts available. That depends on how a person wants to build it.

[Jefscoupe]

Originally Posted by 19Fordy

I wonder if you have to "re-balance" those SCAT cranks?

The new kits are "advertised" as being balanced components.
Now, I've not gotten one...yet...so I can't say for sure.

http://www.speedwaymotors.com/1939-5...4-CI,5401.html

My local guru has built several flatheads recently using this assembly and is convinced they are worth it.