Inliners International Forums General Discussion Hi Performance Flat 6 Port cleanup...Is it worth it?

Hi all-
I'm in the process of a mostly stock rebuild on my 230 Flathead 6. While it's apart would be a great time to do some port work. I'm waiting for parts to arrive anyway. The ports already look ok, and they don't really have any sharp edged to smooth out.

Is it worth it to clean up the ports a bit, or would that be a waste of time for a stock motor. Would I even notice the difference? I will eventually go Turbo with it, but that probably won't be for awhile still, and I'll probably have it apart then anyway. Thanks for the advise.

-Jeff

An engine is basically an air pump and anything that improves airflow improves the engine's breathing. Even a stock engine like yours could benefit from at least softening any sharp edges in the ports. Just don't get carried away because a bad port job is worse than none at all.
I'd just look for casting flash to be removed if any exists and the easing of knife sharp corners if they exist.

Should you decide to mill the head to any extent then the areas from the valve seats to the cylinder bores usually benefit from what was known as "relieving". This was a common performance trick on the Ford Flat head V8 engines.

I thought about relieving the valves. On a Ford V8, the valve seats are sunk down into the block just a bit, so they are below the deck level. That's why you can relieve them relitivly easily. But on a Mopar flathead, the seats are level with the deck so they can'e be relieved without having the seats machined down into the block further. At least that's how it looks to me.

Casting flash is almost nil in my block already, but I'll double check.

-Jeff

Jeff,You could gasket match the intake and exhaust ports initially and do the valving later if you think you want to.

Hi Jeff,

The question that immediately comes to mind is: Why would you sink your valves and then partially unshroud them by relieving the block? I believe that you would decrease the flow around the valves and lower your compression. Not the best way to improve performance.

Jim

In a recent conversation with a famous Inliner/engineer/engine builder, I asked about the benefit of relieving a flathead block. He said there would be NO noticeable difference on a street engine.

You are right Jack in that most porting and relieving produce no noticeable results on a street engine. I probably should have mentioned that the Ford Flatheads were usually given the relief treatment when the heads were milled down for more compression. The milling had the result of shortening the passage height between the valve seats and the combustion chambers, effectively make the "ports" smaller. The reliefs cut into the block opened this back up again so the flow wasn't restricted.