Newly Engineered Flathead Block

Through a combined effort of Motor City and Shadow Rods it’s finally here. A new state of the art Flathead Engine block. Due to health problems back in 2002 I was forced to close shop and pass the ball to Jon Hall, founder and president of Shadow Rods.


Any one that knows Jon knows that he is a perfectionist to the utmost degree. That makes him the perfect candidate to do this project.


First let’s ask- why do a new Flathead Block? Answer: They are just getting too hard to find. On an average you can easily go though 3 or 4 blocks just to find a good one. That can mean endless hours of research just to find one. Purchase it for $100 to $500 just to spend a week taking it apart only to find out the block is cracked or rusted through from the inside out.


Some of the other problems are over heating, oil consumption, excessive crank case pressure, and oil leaking due to bad gaskets and especially bad front and rear main oil seals.



Other draw backs are due to a poor design which include lack of lower end strength due to only 3 main bearings, and insufficient horse power and torque due to poor ports and valve sizing resulting in a very inefficient motor. And last but not least small bores resulting in small cubic inches (STD 239 cu in.)


 To do a block and not answer those questions would be a sin, so our new block is most importantly new. Absolutely no inside rust, no trapped or hidden core sand that can be a cause of over heating.


This new motor is designed for modern lip seals (no more leaking). It has heavy duty main caps including a 4 bolt center made out of ductile iron, eliminating any lower end strength concerns. Valve guides permanently pressed into the block drastically reducing oil consumption and assuring a good valve job.


The ports on this new motor were developed by Paul Schalk (Doctor Flow) on the flow bench. The results were incorporated into the new casting eliminating any need to port and polish.


A redesigned oiling system allowing you to run an oil filtration system with out a special pump or hose inside the oil pan.

And finally at last a big bore. 3 ½ (3.500”) finish bore size from the original 221 cubic inch that had a bore size of 3 1/16 (3.062”). That is a 7/16 (.437”) increase giving you with a stock crank 3 Ύ (3.750”) stroke 289 cubic inches with a 4” stroke 305 4 1/8” stroke 316 cu in, 4 Ό” 327, 4 3/8” 339. That is pretty dog gone significant.

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