The Ford Barn - View Single Post

panic · 05-03-2024, 08:10 PM

The KR comparison is a bit misleading. The engine has a low bore to stroke ratio, which gives good compression (compared to the reverse): 2.745" bore by 3.8125" stroke.
However, the valve seats (which in the Ford are angled toward the bore) are angled away and flow badly due to the cam positions, true of all H-D flathead 4-cam engines: 1929-73 D, R, W, G, V, & U).
A useful feature is that in the KR (and any race-prepared H-D flathead) is to relieve the deck surface directly adjacent to the high edge of each valve seat so that the valve curtain appears instantly when the valve opens; it's not shrouded or sunken.
A light radius can be added to the deep end of the seat as well.

05-03-2024, 08:10 PM	#56
panic Junior Member Join Date: May 2020 Posts: 16	Re: Relieving 8BA Block The KR comparison is a bit misleading. The engine has a low bore to stroke ratio, which gives good compression (compared to the reverse): 2.745" bore by 3.8125" stroke. However, the valve seats (which in the Ford are angled toward the bore) are angled away and flow badly due to the cam positions, true of all H-D flathead 4-cam engines: 1929-73 D, R, W, G, V, & U). A useful feature is that in the KR (and any race-prepared H-D flathead) is to relieve the deck surface directly adjacent to the high edge of each valve seat so that the valve curtain appears instantly when the valve opens; it's not shrouded or sunken. A light radius can be added to the deep end of the seat as well.