Small Block Oil Pump Priming

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dgc333

dgc333

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Saturday I picked up a piece of 5/16 hex rod so I could prime the oil pump on my magnum headed 360.

I have a couple of questions;

1. I put a pressure gauge in the oil sender port next to the distributor and I was only able to get 10 psi with a 1/2" electric drill. Is this to be expected? The drill did slow down once the pump started picking up oil.

2. I hand turned over the engine in 90 degree increments as I was doing this and I was able to get the right side lifters to pump up and got oil up the push rods to the rockers (remember magnum heads) but not the left side. Once the oil flowed to the right side shouldn't it have gone to the left side too? Could I have missed a oil galley plug? I installed threaded plugs on either side of the cam at the back of the engine and pressed in small freeze plugs on either side of the cam up front. I also installed a threaded plug under the oil filter plate.

Any words of wisdom or am I OK with what I saw?
 
You should get more than 10 lbs even with a drill. On early small blocks there was an inside plug on the drivers side in front of the plug that screws in the back of the block. Is this a Magnum block or an early block? I'm not 100 percent sure if the Magnums had this but it is awfully easy to leave out. If you pull the distributer you should be able to see the end of the drivers side oil passage. The end of this passage is where the plug screws in. My experience is strictly with early small blocks and some Magnum head stuff. Just something to think about.
 
Thanks! I will check that out. It's a 78 LA block with magnum heads.

I was reading Larry Sheppard's book "How to Hot Rod Small Block Mopars" there's also a core plug on the right side under the rear main cap. Not even mentioned in the How to rebuild Small Block Mopars I was using as a reference during the assembly.

It's about 4" down into the block and he specifically says if the block was stress relieved (mine was as part of the cleaning process) that this plug must be replaced. If it's missing/leaking you will have low oil pressure.

The bag of core plugs that I got from Mancini had a small plug that looks like the one but since there were several other extra's I assumed that the kit was for more than one engine type and they were extra's.

I will be dropping the pan tonight and take care of that one for sure too.

Glad I primed the pump with the engine still on the stand.
 
If you pull the pan and the rear main you can tell if that plug you are talking about is in there by inserting a long rod down from the top where the oil pressure sending unit screws in. If the rod comes out the bottom of the block you know the plug is missing. Make sure the rod is longer than the block is tall so it doesn't by some freak accident get stuck in there. You may not even need to take the pan off. If you look at the back of the block you can see the outline of the two oil passages that come from the oil filter. This plug goes directly between these two passages. Measure down from the top of the block and you will know roughly how far the rod should slide into the block. If the rod goes a lot further than your measurement then your plug is missing. Hope this helps a little.
 
That's a big help! None of the books I have are to clear about where these passages go.

I have a nice piece of 1/4-20 rod sitting on the bench that will work perfectly. :)

But I did pick up a new oil pan gasket at lunch today just incase I need to remove the pan.
 
moparracer, you nailed it. It was the inside plug on the drivers side oil galley. :)

I didn't drop the pan but a rod in through the oil sender proved it was in there and in the correct location.

Now spinning the oil pump with a drill gives me 30psi and the drivers side lifters pumped right up and oiled the rockers. :)

Thanks for the tip!
 
I am using a standard volume Melling pump and I do not know what the speed of the drill is but it was a lot slower than what it turns without the load.

In any case I was getting plenty of oil flow up through the push rods.

Isn't 85 psi awfully high for the speed you can turn the pump with a drill? The rule of thumb I have always gone by is 10 psi for each 1000 rpm.
 
No I don't think so. How many RPMs does a 1/2 drill turn? Quite alot I supose. I have 60 hot at idle. Close to 90 at first start up. I thought it alot too but it's came down so I'm happy.
 
Well the drill I have is rated for 3000 rpm with no load and it's going a lot slower when it's turning the oil pump, maybe 1500 max.

60 psi hot idle is kind of excessive oil pressure. Unless you run that engine in excess of 6000 rpm all the time you are just eating up horsepower that would normally go to the rear wheels. The books I have read do not recomend a HV pump in small block mopar engines unless you are turning big rpm's.
 
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