I just thought I'd pass along something I saw this week that surprised me no end. A friend is building an early, numbers-matching BBC 427/425 to go in an Impala. Not exactly something I'd do, but pretty cool. This motor oils much like a 409 in that it has a grooved rear cam journal, etc. The cam, lifters, springs were ordered from Comp, and the grind is a tight-lash version of the original GM cam. I'm not building it, just observing.
So it was assembled and primed, and it took quite some time to prime. Being used to 409s, I didn't think too much of it. It started and ran perfectly, except that the oil pressure (standard M-77 pump) was low across the board, particularly at idle. Clearances and lifter bores were right on. So where was the oil going?
I won't bore you with all of the detective work, but there was a bunch of leakage out of the lifters around the edges of the button that seats the pushrod. In fact the button was "loose" in the lifter, you could rattle them. When spinning the pump with a drill, you could see oil gushing out of the lifters and into the valley. I had not seen this before. I just assumed the only path out was the pushrod hole.
A call to Comp resulted in them shipping an upgrade replacement lifter set with a tight-fitting button and an .012 edm hole in the face. Problem solved, but I have no idea why Comp would offer several different levels of solid flat tappet lifters for Chevy engines? I don't generally use Comp stuff so this was a new one to me. I thought I'd pass it along since all of our engines use the same basic lifter, and many of us prefer solids.
So it was assembled and primed, and it took quite some time to prime. Being used to 409s, I didn't think too much of it. It started and ran perfectly, except that the oil pressure (standard M-77 pump) was low across the board, particularly at idle. Clearances and lifter bores were right on. So where was the oil going?
I won't bore you with all of the detective work, but there was a bunch of leakage out of the lifters around the edges of the button that seats the pushrod. In fact the button was "loose" in the lifter, you could rattle them. When spinning the pump with a drill, you could see oil gushing out of the lifters and into the valley. I had not seen this before. I just assumed the only path out was the pushrod hole.
A call to Comp resulted in them shipping an upgrade replacement lifter set with a tight-fitting button and an .012 edm hole in the face. Problem solved, but I have no idea why Comp would offer several different levels of solid flat tappet lifters for Chevy engines? I don't generally use Comp stuff so this was a new one to me. I thought I'd pass it along since all of our engines use the same basic lifter, and many of us prefer solids.