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All you Flathead Ford guys out there, what are your thoughts on relieving an 8BA block ? I know this is a great way to help them breath, but there is a part of me that is hesitant to do it, since I've read some articles about the Flatheads deck being kind of thin. This is a street motor, compression will be kept to 8 to 1, block has never been machined before on deck surface. How deep were the factory relieved blocks ? What is the maximum depth ya'all would go, and any thoughts on shot peening the relief after machining ? Also, last but not least, would a modern CNC Machine , or any other machine, be capable of doing that relief work without leaving a very distinct 90 degree cut between relief and deck ? Sounds like an area that could promote cracks. I've done a relief job on a Flathead many years ago, all by hand that left a smooth transition in that area, but I doubt the relief had the same amount removed from cylinder to cylinder. Any thoughts appreciated !!!
I'm sure you'll get some replies here but, check the Ford Barn forum too. LOTS of info and "opinions" there. The thread will probably break out into some heated discussions. Relieving the block increases flow but, reduces compression. So milling the head is in order. But....then you have to watch valve clearance and so on. Good luck with whatever you decide to do.
Larry, when we built our v8 for a stock truck, we went with a 4” mercury stroke, 1CM mercury cam, and milled the 8BA heads. It pulls like a mule and is very responsive.
Compression is much more beneficial on a street driven, non race, flathead than whatever small improvement in flow you might get from relieving. Factory relief blocks were typically truck units attempting lower compression to control detonation with low octane fuel and/or lean conditions during engine lugging.
I helped a friend rebuild a stock engine for his 1950 Mercury. We did a stock rebuild except replaced the worn out original cam with an EAB cam, and milled the heads to get 0.050 clearance above the pistons. In overdrive we run out of speed limit well before we run out of power or revs, 75 mph speed limit on I-10...
If you like to read up on Ford flathead V8s I recommend the book Flathead Facts by John W. Lawson (findable with a google search).
