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Author Topic:   block difference 509vs.817
last-heat first-feature
Member
posted December 02, 2000 04:17 PM
We are building a splayed cap aftermarket crank 400 and we want to know what the difference is in the two casting numbers for a 400. Is there a difference in the webbing of the block? My machine shop doesn't really know the difference between the 509 and 817 casting, if any. This motor will only turn around 6800-7100 max RPM's. Any preference on the different casting's would be appreciated. Thanks in advance.


junkyard
Member
posted December 02, 2000 05:34 PM
I am told the 509 is the best. I don't know why.


CUSTOMPERFORMANCE
Member
posted December 02, 2000 05:47 PM
I BELEIVE THE DIFFERENCE IN THE 509 IS THEY HAVE A HIGHER NICKEL CONTENT AND LESS CORE SHIFT THAN THE OTHER ONE. BOTH ARE HARD TO FIND SO USE WHICH EVER YOU HAVE ACCESS TO.


dan59
Member
posted December 02, 2000 05:49 PM
From what a very qualified person told me, those two blocks are the ones of choice...but the 817 has a little thicker cylinder wall. They constantly sonic test those blocks. The reason I remember this is because the one I had was an 817. The best way to compare the two blocks is get the cylinders sonic tested. From what I was told again, the main thing you have to watch for on these blocks is to have one that the cylinder my be thin in one area and blow out. When compression and cylinder pressure are increased, there is an increased chance of this happening. If you want, I can get you in touch with a person that can help you on the blocks. Where are you located. Just PM me and let me know.

Jammin

[This message has been edited by jammin (edited December 02, 2000).]

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