200 crank with 170 rods and pistons in a 170 block?

100_2023

Well-known member
Hi guys,

I have found a 4 main bearing 200 crankshaft. I was trying to remember if I use the 200 crank with 170 rods and pistons in a 170 block, does it come up to a 188 CI? Do I need to have custom pistons? or can I just use the stock rods and pistons?

I have a 4 main 170 block. I have checked, and a late model Duraspark distributor does fit in it. I can't remember how you check it for oiling capability for a hydraulic camshaft. I remember checking this before and we decided it did have the capability. Please remind me again what to look for to tell how? I want to make sure. IIRC, it is a C4DE block, but will have to look at the date code on it when I get home.

My plan is to build this up for my reverse trike with a C-4 automatic in a Triumph front car chassis with a swing axle rear chain drive. Kind of make it look like the old Morgan, but with a 6 cyl instead of a V-Twin up front.

I would value your brainstorming and input. There are some great ideas on this forum. Thank you.
 
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The 170 and 200 uses the same connecting rods, but not the same pistons.

The 200 uses a piston with a 3.68" bore and 1.50" compression height (CH).

The 170 uses a piston with a 3.50" bore and 1.58" compression height (CH).

If you use the 170 pistons with the 200 crank, the piston will stick out of the block 0.050", whereas the stock 170 has the piston 0.043" down the bore. That is 0.093" difference; your compression would be excessive, if the pistons didn't hit the valves.

You need to find pistons with the 170 bore (3.50") and the 200 compression height (1.50")
Two Ford pistons may work:
The 86-95 3.0L V6 has a 3.5039" bore and a CH of 1.515"
The 2002+ 3.0L V6 has a 3.5039" bore and a CH of 1.520"
Both pistons have the same 0.912" wrist pin as the 170/200. They would give you a little more compression, but not excessive.

Hope this helps.
 
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