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FE Power Forums => FE Technical Forum => Topic started by: Fordman on January 11, 2019, 10:12:37 PM

Title: Cylinder wall thickness BBM Blocks
Post by: Fordman on January 11, 2019, 10:12:37 PM

While doing some info digging I came across a post on the old forum regarding info that the BBM rep had posted regarding the upcoming heads, and block. The rep stated that cylinder wall thickness during testing/sonic mapping the blocks is that they had .330 to .450 thou at 4.250" bore. They state a 4.440 maximum bore size. If the bores maintained a minimum of .330 though out the bores at 4.440" there would still be a minimum .250 cylinder wall thickness. If we were to go with popular opinion of a .150 thou minimum would the maximum bore size not be closer to 4.600". Am I way off here or am I missing something?....Opinions welcome.....John

Title: Re: Cylinder wall thickness BBM Blocks
Post by: Drew Pojedinec on January 11, 2019, 10:32:46 PM

4.630 cylinder spacing on centers.
I think you need to divide your numbers by 2.

Title: Re: Cylinder wall thickness BBM Blocks
Post by: jayb on January 11, 2019, 10:46:24 PM

I've only built one engine with one of those blocks, but the cylinders were nowhere near that thick, more like 0.230"-0.250" at 4.250" bore according to my sonic checker.  My Pond cast iron block is thicker.

Title: Re: Cylinder wall thickness BBM Blocks
Post by: SAcobra427 on January 14, 2019, 04:08:04 PM

John,   Are you talking about a BBM cast iron or aluminum block here? I just got a cast iron one and I was planning on having it sonic checked to see what it has.

Title: Re: Cylinder wall thickness BBM Blocks
Post by: Fordman on January 15, 2019, 09:18:22 AM

Iron block. I am interested to hear your results.  Please post them when you have it done. Thank you

Title: Re: Cylinder wall thickness BBM Blocks
Post by: mike7570 on January 15, 2019, 12:51:00 PM

Quote from: Fordman on January 11, 2019, 10:12:37 PM

While doing some info digging I came across a post on the old forum regarding info that the BBM rep had posted regarding the upcoming heads, and block. The rep stated that cylinder wall thickness during testing/sonic mapping the blocks is that they had .330 to .450 thou at 4.250" bore. They state a 4.440 maximum bore size. If the bores maintained a minimum of .330 though out the bores at 4.440" there would still be a minimum .250 cylinder wall thickness. If we were to go with popular opinion of a .150 thou minimum would the maximum bore size not be closer to 4.600". Am I way off here or am I missing something?....Opinions welcome.....John

I picked up an iron 428 BBM from Doug and I think he gave me the same thickness but I thought he was talking about the standard 4.13 bore not 4.25.

Title: Re: Cylinder wall thickness BBM Blocks
Post by: Fordman on January 18, 2019, 01:22:41 AM

Thanks Doug. That would make more sense to the cylinder wall spec....John

Title: Re: Cylinder wall thickness BBM Blocks
Post by: TomP on January 18, 2019, 03:34:26 PM

I think head gaskets could be a bit of an issue at 4.60" bore. ???

Title: Re: Cylinder wall thickness BBM Blocks
Post by: jayb on January 18, 2019, 04:55:48 PM

TomP, Mr. Understatement  ;D ;D

Title: Re: Cylinder wall thickness BBM Blocks
Post by: 427HR on January 20, 2019, 01:42:26 PM

My BBM iron block sonic test:

Title: Re: Cylinder wall thickness BBM Blocks
Post by: Joe-JDC on January 20, 2019, 02:45:44 PM

Is this sonic test with the bores at 4.345"?  If so, then they look really strong.  Joe-JDC