Winger Ed.
Member
Kinda got a head scratcher:
I've rebuilt a 70's era GM 4cy. Merc. 120. Its in front of a 90's era Mercruiser outdrive.
The engine is low hours, it still has the ghost (barely visible pattern) of the factory crosshatch pattern in the cylinders. The rebuild went perfect: New lifters, crankshaft bearings, pistons, etc. The bearing tollerances are text book perfect. The engine was so low time, I did use the original factory oil pump that looked fine. Compression is good enough it will idle down below 650, and after a couple hours, the oil is still yellow.
The engine couldn't start or run any better. I put new (electric)Farina guages in and re-wired it. It's all perfect, except the oil pressure reads low in the 20-ish psi instead of being in the 30's. It has (Valvoline) straight 30 weight in it like the book calls for. I put a new sending unit on the block, but the reading didn't change.
The oil flow & such looks fine when I removed the valve cover. At a low idle- 700, its quiet,
and oil is flying out of the pushrod end of the rocker arms like you'd expect to see.
I haven't put a different mechanical guage on it, but was wondering if the wire going from the sender to the guage would let it read low if it was too long, or the wrong size. I re-wired the dash with plain stranded 16 guage. I think its getting power just fine, the new alt. is reading 14 volts on the dash guage.
Thanks for any input.
I don't think the engine is in danger. If it only had a dash light for oil pressure monitoring-
it wouldn't light up unless the pressure was below 5 or 10 pounds.
Its just that as well as it went together,
and as simple of a engine as it is anyway, I think the pressure should read higher.
I've rebuilt a 70's era GM 4cy. Merc. 120. Its in front of a 90's era Mercruiser outdrive.
The engine is low hours, it still has the ghost (barely visible pattern) of the factory crosshatch pattern in the cylinders. The rebuild went perfect: New lifters, crankshaft bearings, pistons, etc. The bearing tollerances are text book perfect. The engine was so low time, I did use the original factory oil pump that looked fine. Compression is good enough it will idle down below 650, and after a couple hours, the oil is still yellow.
The engine couldn't start or run any better. I put new (electric)Farina guages in and re-wired it. It's all perfect, except the oil pressure reads low in the 20-ish psi instead of being in the 30's. It has (Valvoline) straight 30 weight in it like the book calls for. I put a new sending unit on the block, but the reading didn't change.
The oil flow & such looks fine when I removed the valve cover. At a low idle- 700, its quiet,
and oil is flying out of the pushrod end of the rocker arms like you'd expect to see.
I haven't put a different mechanical guage on it, but was wondering if the wire going from the sender to the guage would let it read low if it was too long, or the wrong size. I re-wired the dash with plain stranded 16 guage. I think its getting power just fine, the new alt. is reading 14 volts on the dash guage.
Thanks for any input.
I don't think the engine is in danger. If it only had a dash light for oil pressure monitoring-
it wouldn't light up unless the pressure was below 5 or 10 pounds.
Its just that as well as it went together,
and as simple of a engine as it is anyway, I think the pressure should read higher.
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