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08-07-2019, 08:06 AM | #21 |
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Re: 1CM Merc Crank In A 40?
Fordestes: What you mention is more of an issue if you're trying to get to a cast piston - not so much with forged pistons - where the big determining factor is do they have a forging blank of the right size to work from.
Now they may charge you more to do the machine work (as it is not a typical high-production stocking piston), but the process really is no different for whatever bore size, ring package and compression height you require. If I was into the world of 221 blocks, I'd check with a few piston manufacturers to see who has a good forging blank that can support your needs and not end up with a piston that is too heavy, too short, etc.. This usually requires a basic CAD drawing of what you're looking for - so they can check with Engineering to see what they have to work from. |
08-07-2019, 08:09 AM | #22 |
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Re: 1CM Merc Crank In A 40?
Hey Gary - I think you meant 3.228 at the start of your post --- .040 over the stock 3 3/16 bore (3.1875 + .040).
Good info on the big-end sizes of the SCAT rods. They will not work in this 221 world - so it is back to the 91A or 21A rods for the smaller bore sizes - 3 1/16 |
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08-07-2019, 10:44 AM | #23 |
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Re: 1CM Merc Crank In A 40?
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08-07-2019, 10:49 AM | #24 | |
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Re: 1CM Merc Crank In A 40?
Quote:
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08-07-2019, 12:53 PM | #25 |
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Re: 1CM Merc Crank In A 40?
That is correct 1.998 is the stock size for the 91A/21A Rods. However I dn't know where you'd get the pistons?? also you have to consider balancing the assy??sounds like a very complicated and expensive project?? For what purpose??
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08-07-2019, 01:34 PM | #26 |
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Re: 1CM Merc Crank In A 40?
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08-07-2019, 02:45 PM | #27 |
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Re: 1CM Merc Crank In A 40?
Pistons have to match the crank stroke. All of the rods are the same length so the piston pin location has to move up to accommodate a larger stroke.
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08-07-2019, 04:40 PM | #28 |
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Re: 1CM Merc Crank In A 40?
You could use french rods. 6 3/4 length. Or use a set of OFFY heads and recess the pistons, creating a much higher CR. Boy wouldn't that be a torker.
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08-07-2019, 06:26 PM | #29 |
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Re: 1CM Merc Crank In A 40?
About a week ago, we determined in a thread that I started, asking for the deck height of the FH, that the deck height, is 10.440 - 10.445. So, I will use 10.442 for the following:
1/2 Stroke = 2" Rod length = 7.0" Piston CH = 1.527 (this measurement is from my piston) -------------------- 10.527 10.527 - 10.442 --------- .085 - .070 (Cometic SS headgasket) --------- .015 Piston above head gasket My piston is .250, to the top ring so, it's still well below the cylinder. You can chamfer the corner of the piston, .060 at 30 deg and then assemble and check the clearance, to the head with clay. If there isn't enough clearance, in the inboard area, modify the chamfer angle. Just a suggestion but, it wouldn't cost much to modify a junk piston to find out. Frank |
08-07-2019, 08:59 PM | #30 |
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Re: 1CM Merc Crank In A 40?
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08-07-2019, 10:26 PM | #31 |
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Re: 1CM Merc Crank In A 40?
One way to install 8BA rods into a 3 1/16 bore is to install the rods from the bottom. Then install the pistons and wrist pin from the top. Using a ring instillation tool install piston and rod on crank, WE gota see this engine get built!!!!
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08-08-2019, 11:30 AM | #32 |
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Re: 1CM Merc Crank In A 40?
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08-08-2019, 12:17 PM | #33 |
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Re: 1CM Merc Crank In A 40?
The engine will have very little compression with a 6 3/4" rod. You would have to run the 4 1/4 crank to get the piston up to the stock deck clearance.
Frank |
08-08-2019, 01:26 PM | #34 |
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Re: 1CM Merc Crank In A 40?
Will the 4 1/4 crank work in a 3 1/16" bore with the French rod and stock 221 pistons? How good would it run?
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08-08-2019, 01:42 PM | #35 |
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Re: 1CM Merc Crank In A 40?
As far as running strong, it diffidently would but, I know nothing about the French rods but, assume the crank will fit in a post '40 block. Internal, crankcase dimensions should be the same as the 3 3/16" bore Merc blocks.
I would think the French rods would be very rare in the USA. |
08-08-2019, 02:40 PM | #36 |
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Re: 1CM Merc Crank In A 40?
The French rods are for 2.138 crank journals the 4 1/4 stroke cranks I have seen ( scat eagle welded merc )have 2 inch rod journals
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08-08-2019, 03:10 PM | #37 |
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Re: 1CM Merc Crank In A 40?
The French military used a version of the Ford flathead for many years after production stopped in the US. Some years back they sold off all of the surplus FH stuff, complete engines, blocks, cranks, rods, etc. A lot of the surplus came to the US and is still available.
"The Ford flathead V8 was licensed to other producers. It was used by Simca in France until 1961 and in Brazil until 1964 for cars and until 1990 in the Simca Unic Marmon Bocquet military truck. In the United States, the flathead V8 was replaced by the more modern overhead-valve Ford Y-block engine in 1954." The dates for production in France are all over the place, I have no idea what the last production date was, but all surplus now. http://www.reds-headers.com/html/ffh.html http://www.btc-bci.com/~billben/french.htm Last edited by JSeery; 08-08-2019 at 03:36 PM. |
08-08-2019, 03:11 PM | #38 |
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Re: 1CM Merc Crank In A 40?
But, the Speedway 4.25 crank, that I posted about earlier, is 2.138 on the rods. It's a little pricey at $750 though. But, it is a Scat crank.
https://www.ebay.com/itm/Scat-9-239-...ss!97502!US!-1 |
08-08-2019, 03:38 PM | #39 |
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Re: 1CM Merc Crank In A 40?
Excellent. I did not know.
Good luck |
08-08-2019, 03:56 PM | #40 |
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Re: 1CM Merc Crank In A 40?
I happen to have a Scat 4 1/4 crank laying around, just measured it and it is 2.000". Interesting.
Just looked at their site, they have both throw sizes listed for a 4 & a 4 1/8, but not 4 1/4. Shouldn't be much of an issue to produce a larger dia throw on a 4 1/4 though. Last edited by JSeery; 08-08-2019 at 04:10 PM. |
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