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Mine is plumbed in the front port but I'm not sure if that is factory correct. Before I looked I would have said the smaller, rear port. Hopefully someone will chime in as I suspect the rear port is where the factory plumbed them. I believe the front two ports are for oil cooler connections.
John, the oil line connects to the front hole. The factory style plug for the center hole has a square recess in it so the plug can be tightened with a ratchet drive or breaker bar directly.
I didn't find anything clear in the AIM but I'm pretty sure the small rear port was factory. The hydraulic lifter BBs would not have the front port for an oil cooler, opened and tapped.
Something else not NCRS on my car.
Edit:
Well, we have votes for the front and the rear ports. I see lots of picutres with senders in the large center hole too so it appears the answer may be somewhat elusive.
JohnZ??
Last edited by DansYellow66; Jan 11, 2015 at 09:47 AM.
Here's a pic I "borrowed" some time ago showing how BB's were plumbed from St. Louis. Chevelle BB's from Fremont were a little different but they used an electric sending unit. Maybe JohnZ will confirm.
Now that I think about it - I think the rear hole is blind and Mike67nv photo seems to confirm. Cars with sending units seem to have them installed in the middle hole. My 4-bolt main block is plumbed as shown in this photo above also (but don't know if it's corrrect). But 2-bolt main blocks do not have the front hole drilled which only leaves them the middle one (or am I forgetting something?)
It doesn't seem like GM would plumb the oil line on mechanical lifter blocks to the front and the oil line on hydraulic lifter blocks to the middle hole in 66 and 67 Corvettes??
The photo above is correct for the 4-bolt blocks - leaves the middle hole available for an oil cooler connection, which is why it's there. On a 2-bolt block, the forward hole isn't drilled, so the drilled oil pressure tap is the hole immediately above the center of the oil filter canister (same hole used for the oil cooler on a 4-bolt block, but smaller). Photo of 2-bolt block below.
Here's a pic I "borrowed" some time ago showing how BB's were plumbed from St. Louis. Chevelle BB's from Fremont were a little different but they used an electric sending unit. Maybe JohnZ will confirm.
Only chevelles with the standard warning light dashes got the electric sending unit. cars with the U14 special instrumentation got a mechanical gauge in the dash
Only chevelles with the standard warning light dashes got the electric sending unit. cars with the U14 special instrumentation got a mechanical gauge in the dash
I know they changed over time and the years are somewhat of a blur now, but the electric sending units I was remembering looked something like the link below. Most, if not all, SS396’s and SS454’s came with gauges. Whenever they switched to electric sending units, it screwed into a brass 45* elbow in the forward hole above the oil filter.
I know they changed over time and the years are somewhat of a blur now, but the electric sending units I was remembering looked something like the link below. Most, if not all, SS396’s and SS454’s came with gauges. Whenever they switched to electric sending units, it screwed into a brass 45* elbow in the forward hole above the oil filter.
66 427 4-bolt oil line connection
