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Does the oil passage at the rear main upper bearing saddle get a push plug installed, or does the upper bearing insert act as a dam? I would think a plug should be installed , but what do i know.
It looks like the front (small) threaded hole above the oil filter is the oil pressure take off port?
What should I use as sealant for the threaded oil galley plugs? I don't like the idea of teflon tape due to possibility of small pieces of tape coming loose into the system. Permatex #1 on the plug threads (NOT in the threaded hole)?? Something else??
Should the two front plugs behind the timing sprocket be vented (1/32" hole) for chain oiling?
Are brass plugs OK vs steel/iron?
I see that large thread hole in the flywheel area behind the oil filter, i know it needs plugged. Do small blocks have a plug there?
Regarding your question about drilling a small hole in the two oil passage plugs above the cam...for chain oiling purposes, I like to do that. Glad you brought up that question because while the 2-bolt 427 I'm building now for my 65 NOM L78 Roadster has those two plugs drilled, the 4-bolt '66 #942 block I just had machined does not have those plugs drilled and I'm going to change that.
Mike T - Prescott AZ
It's a GM ZZ427 Hydraulic Roller Cam so it already had the step nose design. The old '69 vintage block had the two holes tapped for the retainer which was the way I wanted to go in lieu of the cam button arrangemetnt.
Mike T - Prescott AZ
No press in plugs on a BBC. The 1/8" npt is for the oil pressure sending unit. The hole coming from the rear is BB only. It's intersects the hole down the side of the block along the pan rail that feeds all of the mains. I use Teflon tape with a touch of oil. I make sure to push any overhanging Teflon back towards the threads on the plug before I install the plug to keep from getting Teflon in the passage.
Are you working on a Mark IV block ?
I like teflon pipe sealer on the threaded plugs , not the tape
I like bronze freeze plugs, epoxy for a sealer
Drilling the plugs behind the cam gear will bleed off air trapped in the system and a little oil pressure keep em small .
Regarding sealant, I’ve always used Permatex Avaiation Sealant #80017, and removed all the excess following tightening. Drilling holes in the plugs mentioned? Some builders do it, an experienced bbc builder I knew did it routinely, but only on the right side (#2 cylinder side)….. and he also always used hi volume factory L-88 spec pumps
So the upper rear main bearing insert just acts as a dam for that 1/2" hole drilled from the upper main bearing saddle into the passage from the oil pump to the filter?
The Bowtie block i have has two larger pipe tapped holes above the oil filter boss (3/8" and 1/2" to my eyeball), guess I will plug the large one and bush the front, smaller one down to 1/8" for a pressure gauge take off.
Thanks,
Doug
Originally Posted by Robert61
No press in plugs on a BBC. The 1/8" npt is for the oil pressure sending unit. The hole coming from the rear is BB only. It's intersects the hole down the side of the block along the pan rail that feeds all of the mains. I use Teflon tape with a touch of oil. I make sure to push any overhanging Teflon back towards the threads on the plug before I install the plug to keep from getting Teflon in the passage.
……… i have has two larger pipe tapped holes above the oil filter boss (3/8" and 1/2" to my eyeball), guess I will plug the large one and bush the front, smaller one down to 1/8" for a pressure gauge take off.
This is what I believe is the correct configuration (see where line is attached), the other picture shows the size/thread of the holes in question
Big Block oil system questions
