oil pump selection
You'd be better off re-using your stock pump than the standard Melling or other cheap castings.
I've had a 250k mile stock GM used pump and a new "standard" Melling disasembled side by side. The 250k stock pump was in better shape. The fit of the gears in the housing of the Melling pump was inferior to the old used pump.
I've had a 250k mile stock GM used pump and a new "standard" Melling disasembled side by side. The 250k stock pump was in better shape. The fit of the gears in the housing of the Melling pump was inferior to the old used pump.
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Teching In
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You'd be better off re-using your stock pump than the standard Melling or other cheap castings.
I've had a 250k mile stock GM used pump and a new "standard" Melling disasembled side by side. The 250k stock pump was in better shape. The fit of the gears in the housing of the Melling pump was inferior to the old used pump.
I've had a 250k mile stock GM used pump and a new "standard" Melling disasembled side by side. The 250k stock pump was in better shape. The fit of the gears in the housing of the Melling pump was inferior to the old used pump.
Last edited by platinum performance; Sep 12, 2016 at 11:05 PM. Reason: Bad spelling
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Brett Foote If using GM stock, you can:
1. leave it alone (just fine if you're keeping revs below ~6k).
2. replace the relief spring with a GM "white" spring or equivalent (this delays bypass and improves flow to the bearings at high revs)
3. stretch the standard GM stock spring so its free length is about 1/4" longer and accomplish the same as #2.
Teching In
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Help Ok I built a l83 used the stock pump didn’t know about the alignment tools until after the engine was I assembled fired it up 10lbs of oil pressure at idle. Hit the gas and it goes up. Bought a new pump same problem. Changed out the barbel at the back of the block same problem. What am I missing?
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
Ok I built a l83 used the stock pump didn’t know about the alignment tools until after the engine was I assembled fired it up 10lbs of oil pressure at idle. Hit the gas and it goes up. Bought a new pump same problem. Changed out the barbel at the back of the block same problem. What am I missing?
TECH Addict
Joined: Oct 2016
Posts: 2,513
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From: PDX-OR-USA
FWIW,, I have a rebuilt L33, came from Jegs,
Built by their supplier. Basically a standard factory reman,
runs in the 40PSI range at cruise when hot, bumps to almost 60 under WOT and idles at 25 or so lbs..
Not sure I'd need any more with anything I drive on the street.
Built by their supplier. Basically a standard factory reman,
runs in the 40PSI range at cruise when hot, bumps to almost 60 under WOT and idles at 25 or so lbs..
Not sure I'd need any more with anything I drive on the street.
On The Tree
Joined: Jul 2021
Posts: 120
Likes: 15
From: Killeen TX
Stop thinking about any more volume than stock! No benefit; only potential problems.
If using GM stock, you can:
1. leave it alone (just fine if you're keeping revs below ~6k).
2. replace the relief spring with a GM "white" spring or equivalent (this delays bypass and improves flow to the bearings at high revs)
3. stretch the standard GM stock spring so its free length is about 1/4" longer and accomplish the same as #2.
If using GM stock, you can:
1. leave it alone (just fine if you're keeping revs below ~6k).
2. replace the relief spring with a GM "white" spring or equivalent (this delays bypass and improves flow to the bearings at high revs)
3. stretch the standard GM stock spring so its free length is about 1/4" longer and accomplish the same as #2.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
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Only reason to use a HV pump is if the bearing clearances were set up slightly wider than stock. Some performance rebuilds are done this way which will often see 7k RPM use and run 20-50 wt oil.
standard bearing clearance a HP pump is fine or stock one with the "white" spring
standard bearing clearance a HP pump is fine or stock one with the "white" spring
I broke the plastic oil pump drive housing in less than 1000 miles on mine, using a HV oil pump. It was a brand new in the box AC Delco housing too. and that was even with my main and rod bearing clearances both loosened up from factory and using 10-30 oil.
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
I use a standard volume big block pump with a high pressure spring on all my small blocks. GM uses that same pump with the same LT1 drive in the 8.1s.
TECH Veteran
Joined: Apr 2008
Posts: 4,985
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I also run the Melling metal one piece OP drive shaft
I had "heard" my entire life about HV pumps sucking the pan dry and didn't believe it until I put one in my friends 93 z28 when I rebuilt his engine(many many years ago)
Well it's true, at least in this situation. Put a stock pump in it and took care of the oil pressure going away at high RPM's.
I will say it was using the stock pan and stock bearing clearances.
Well it's true, at least in this situation. Put a stock pump in it and took care of the oil pressure going away at high RPM's.
I will say it was using the stock pan and stock bearing clearances.
TECH Resident
Joined: Oct 2006
Posts: 993
Likes: 173
From: Euless, TX
I had "heard" my entire life about HV pumps sucking the pan dry and didn't believe it until I put one in my friends 93 z28 when I rebuilt his engine(many many years ago)
Well it's true, at least in this situation. Put a stock pump in it and took care of the oil pressure going away at high RPM's.
I will say it was using the stock pan and stock bearing clearances.
Well it's true, at least in this situation. Put a stock pump in it and took care of the oil pressure going away at high RPM's.
I will say it was using the stock pan and stock bearing clearances.