High Volume Oil Pump Observation
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
High Volume Oil Pump Observation
When replacing the heads on my '81 since it took me so long, I used my drill to drive the oil pump several times and during this I noticed something that I want to ask about.
With the intake off, heads, lifters, pushrods, all installed, I ran the oil pump with a drill. What I noticed was that oil came up out of the distributor shaft hole...and it was quite a bit. I had oil come up out of the lifter bores and had oil into the heads from the pushrods....but it was the amount of the oil out of the distributor hole that bothered me.
I assumed that this is just due to the high volume oil pump. I did not change the spring in the oil pump...it is not high pressure.
Is this normal or do I have a bad oil pump?
With the intake off, heads, lifters, pushrods, all installed, I ran the oil pump with a drill. What I noticed was that oil came up out of the distributor shaft hole...and it was quite a bit. I had oil come up out of the lifter bores and had oil into the heads from the pushrods....but it was the amount of the oil out of the distributor hole that bothered me.
I assumed that this is just due to the high volume oil pump. I did not change the spring in the oil pump...it is not high pressure.
Is this normal or do I have a bad oil pump?
Le Mans Master
Joined: Apr 2001
Posts: 5,941
Likes: 281
From: Was New Orleans but swam to Baton Rouge LA
Cruise-In IX Veteran
Are you sure it is the distributor hole and not the hole for the oil pressure line or sender? I only ask because I had forgotten about the oil pressure hole in the back of the block right there by the distributor and it squirted me before.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
I'm trying to get my head wrapped around this. The back of the cam "floats" a bit on oil film between it and the rear cam plug...I suppose it could be a fair bit. I can't think of anywhere else for the oil to come from other than the cam bearings.
I've never preoiled with the intake off, so I can't speak from personal experience.
What was the point in running the oil pump with the intake off?
I've never preoiled with the intake off, so I can't speak from personal experience.
What was the point in running the oil pump with the intake off?
Last edited by billla; Aug 30, 2011 at 11:45 AM.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
Been there, but that's on the top of the block and he had the intake off...so it's where the bottom of the distributor fits in...I think.
Le Mans Master
Joined: Sep 2004
Posts: 5,116
Likes: 5
From: Livonia MI
The distributor does have a lube hole squirting at it, and will be lots of oil when doing the drill pre-lube thing. Doesn't matter what kind of pump you're using, as same things gonna happen. You can jam a rubber plug in there for testing, but would highly suggest hanging a string on it.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
The distributor does have a lube hole squirting at it, and will be lots of oil when doing the drill pre-lube thing. Doesn't matter what kind of pump you're using, as same things gonna happen. You can jam a rubber plug in there for testing, but would highly suggest hanging a string on it.
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
I'm trying to get my head wrapped around this. The back of the cam "floats" a bit on oil film between it and the rear cam plug...I suppose it could be a fair bit. I can't think of anywhere else for the oil to come from other than the cam bearings.
I've never preoiled with the intake off, so I can't speak from personal experience.
What was the point in running the oil pump with the intake off?
I've never preoiled with the intake off, so I can't speak from personal experience.
What was the point in running the oil pump with the intake off?
And no it was not the oil pressure outlet at the back of the block...I had put the oil pressue sender on to keep oil from coming out. And by the way...with engine running, oll pressue gauge shows a bit over 40 at idle.
This distributor lube hole....if that is where the oil was coming from...why would the oil come up into the lifter valley? I would think it would just fall back onto the oil pump and into the pan.
Race Director
Joined: Mar 2006
Posts: 14,112
Likes: 28
From: Florida
What you saw is normal.
The priming tool you used should also have the 2 lands, but will not fit as snug as a dist.
The 2 lands on the lower dist housing are meant to form a fairly decent seal to the oil pressure cavity. The large hole in the dist shaft is just a vent to prevent any oil pressure from being forced up the shaft by the top bushing and into the dist electrics.
Note in the pic how the oil passage splits at the rear of the cam where the dist shaft sits.
Some aftermarket dist have orings on the lands to prevent excessive leakage and/or have a very tiny hole between the 2 lands to lube the lower bushing/bearing.
The priming tool you used should also have the 2 lands, but will not fit as snug as a dist.
The 2 lands on the lower dist housing are meant to form a fairly decent seal to the oil pressure cavity. The large hole in the dist shaft is just a vent to prevent any oil pressure from being forced up the shaft by the top bushing and into the dist electrics.
Note in the pic how the oil passage splits at the rear of the cam where the dist shaft sits.
Some aftermarket dist have orings on the lands to prevent excessive leakage and/or have a very tiny hole between the 2 lands to lube the lower bushing/bearing.
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Racer
Joined: Feb 2008
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From: Streator Illinois
I wouldn't think that preoiling is even necessary for that short of time of 2 1/2 months. A few of my cars sit that long and longer sometimes, especially during winter storage, without preoiling on startup.
Terry
Terry
Thread Starter
Melting Slicks
Joined: Nov 2005
Posts: 3,323
Likes: 142
From: Green Valley Arizona
Now I know for sure that I have oil flow to the heads....I had the valve covers off when I did this and had oil dripping out.