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Only 40lbs oil pressure after re-build.
- Thread starter Xray50
- Start date
WETTE VETTE
New member
Hook up a mechanical guage and see if it agrees. Have you changed the oil and filter since break in?
old377guy
Charter Member
So there you have it xray, Paul in our technical dept. has determined that it is weird
Ratickle
Founding Member / Super Moderator
ROGUE
Charter Member
First thing that comes to mind is the pressure relief valve in the oil pump. Was the spring removed before the pickup was welded on? If not, it could have gotten hot and lost it's "spring" . If are sure of all the oil plumbing and the preesure reading, I would change the oil pump first.
Mopower
New member
Had an engine do a similar thing. Only 40 lbs cold and would drop to 5 lbs at idle when warm. Running 30 to 35 lbs. Problem turned out to be rods. Top to bottom they miked good, side to side at the parting line they were way large. Squashed then a bit in a press, clipped them and resized them until they were round. Then 70 cold, 60 warm and running and 40 at idle warm
Just my experience
Just my experience
ROGUE
Charter Member
Yeah, I cringed when I read you used plastiguage, thats not an accurate way to setup an engine. And like Mopower said, rods have to be resized. By your brief description, I took it to mean that you have 40 lbs all the time, idle and wot, hot or cold, if thats the case, look to the oil pump relief valve.
ROGUE
Charter Member
I use a good set of micrometers, outside set and inside set. I prefer Starretts. They need to be accurate to a tenth and everything must be temperature equalized. I check three spots on each journal then the same at 90 degrees off and then mount each bearing and check them also. If anything is not right where I want it, it gets remachined. Sometimes I use bearings that are 1 under or 1 over if that gets me the right clearances.
Blue Thunder
New member
Yes, what rogue said. You use 1/2 shells in 1 over/under to get the .0005".
afr
New member
when i assemble a engine i always do both mic crank and rods torqued up and plastic gauge to see if they match kinda a double check thing
i have seen the cam bearing be off a bit and give a low pressure reading as well you got lucky a pump is far cheaper
another check i do on a new motor is after the break in oil i cut the oil filter open to read how the break in went
i have seen the cam bearing be off a bit and give a low pressure reading as well you got lucky a pump is far cheaper
another check i do on a new motor is after the break in oil i cut the oil filter open to read how the break in went
Xray50
New member
Thanks for all the great info. I may have gotten lucky this time but will do it better next time. If you want to go fast you're going to pay for it one way or another. No engine lasts forever. I want triple digits. As soon as I get the engine broken in I got to get my slip factor down. I'm at 18%! Way to high for my Cat! I got to wait acouple of months. My wife will have me sleeping in the garage if I drop $1500 right now for a 5 blade!
