At long last my S2 Frankenmotor build

PostPost by: Roadhouse » Thu Mar 30, 2023 6:38 pm

I am building a motor for my ‘65 S2 that’s been apart for decades. I bought it in 1971 at the tender young age of 17. I was making a $1.35 an hour and had dreams of Lotus Elan based largely on the pen and ink drawings in the full page ad's in Road and Track in the mid sixties.
My original block was bored .040 over and being an early block is not a good candidate for liners considering the core shift in early 5 main blocks. So I decided to build a 1950cc tall block twincam. I bought what is apparently the only stroker crank available, through John McCoy of Omnitech Eng. It’s going to be a while before he can have anymore made. I bought the crank and the block out of a “wickedly fast” Seven that dominated the racetrack. After 5 races officials measured the stroke and made him downsize to a 1558 block and crank. I also bought a set of Carillo rods and 85mm pistons.
Dreams do come true!
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PostPost by: rgh0 » Thu Mar 30, 2023 11:37 pm

I hope you have done an ultrasonic survey of the block. 85mm bores push the wall thickness below the desirable minimum in most blocks.

By the way, the core shift and bore casting diameter variations occur in all the blocks from early 116E to last 701M or 711M

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PostPost by: rgh0 » Fri Mar 31, 2023 3:35 am

I guess you have the 86mm stroke crank and the block you have is a 1600. I also presume you got rods and pistons based on Johns recommendation to suit the 1950cc build. What rod length and piston compression height do you have

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PostPost by: Roadhouse » Sun Apr 02, 2023 3:24 am

I am purchasing them through John. After he ports the head and opens the Webers and intake runners to 45mm and goes through the head I'll get the crown to deck distance from him. He probably built the original motor so he will be familiar with it. The block was a new Ford performance block so no worries about the 85mm bores. It already ran 5 races decimating the competition.
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PostPost by: rgh0 » Sun Apr 02, 2023 3:49 am

Roadhouse wrote:I am purchasing them through John. After he ports the head and opens the Webers and intake runners to 45mm and goes through the head I'll get the crown to deck distance from him. He probably built the original motor so he will be familiar with it. The block was a new Ford performance block so no worries about the 85mm bores. It already ran 5 races decimating the competition.



I have measured up a couple of the new Ford blocks and neither of them would go to 85 mm with 3 mm minimum wall thickness. Ford themsleves now say that the blocks should not be bored beyond 83.5 mm. You may be lucky but I would check the bore wall thickness via a detailed ultrasonic survey before building your motor based on it.

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