Large Holley mechanical pump problem.
Thread Starter
Race Director
Joined: Jan 2002
Posts: 11,620
Likes: 350
From: No Where USA
Large Holley mechanical pump problem.
Is anyone using the large holley mechanical pump. I am having trouble getting the fittings to fit in the chassis. I am using 2 elbows for #6 braided line and can't get the,m in a position that will work.
If you have picture that would help.
If you have picture that would help.
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
What model pump?
Big block or small block?
I installed a Holley mechanical pump last winter on my SBC and I ended up opening the housing and re-drilling the 5 or 6 holes that hold the halves together so I could clock the bottom half to a position where I could get the inlet and outlet positions to somewhat match the OEM locations.
Elm
Big block or small block?
I installed a Holley mechanical pump last winter on my SBC and I ended up opening the housing and re-drilling the 5 or 6 holes that hold the halves together so I could clock the bottom half to a position where I could get the inlet and outlet positions to somewhat match the OEM locations.
Elm
Thread Starter
Race Director
Joined: Jan 2002
Posts: 11,620
Likes: 350
From: No Where USA
What model pump?
Big block or small block?
I installed a Holley mechanical pump last winter on my SBC and I ended up opening the housing and re-drilling the 5 or 6 holes that hold the halves together so I could clock the bottom half to a position where I could get the inlet and outlet positions to somewhat match the OEM locations.
Elm
Big block or small block?
I installed a Holley mechanical pump last winter on my SBC and I ended up opening the housing and re-drilling the 5 or 6 holes that hold the halves together so I could clock the bottom half to a position where I could get the inlet and outlet positions to somewhat match the OEM locations.
Elm
It's the 110 gph and it's a small block. And your idea sounds good I don't know how I didn't think of it. Sometimes you don't see the obvious. Thanks.
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
Sounds like you have the exact same pump and issue I did.
No matter how I clocked the pump, the fittings were just in a bad spot-
So I made my own holes.
Part of the problem is that there are only 5 or 6 bolts, which gives very limited options. Some of the other pumps (I think maybe Edelbrock?) have like 12 bolts so you have a much finer adjustment range. Of course, me being as cheap as I am, couldn't justify paying twice as much for essentially the same pump just for the extra holes.
Actually, I bought the Summit brand pump because it's the Holley pump (same casting number and everything) only private labeled and cheaper yet!
No matter how I clocked the pump, the fittings were just in a bad spot-
So I made my own holes.
Part of the problem is that there are only 5 or 6 bolts, which gives very limited options. Some of the other pumps (I think maybe Edelbrock?) have like 12 bolts so you have a much finer adjustment range. Of course, me being as cheap as I am, couldn't justify paying twice as much for essentially the same pump just for the extra holes.
Actually, I bought the Summit brand pump because it's the Holley pump (same casting number and everything) only private labeled and cheaper yet!
Thread Starter
Race Director
Joined: Jan 2002
Posts: 11,620
Likes: 350
From: No Where USA
Sounds like you have the exact same pump and issue I did.
No matter how I clocked the pump, the fittings were just in a bad spot-
So I made my own holes.
Part of the problem is that there are only 5 or 6 bolts, which gives very limited options. Some of the other pumps (I think maybe Edelbrock?) have like 12 bolts so you have a much finer adjustment range. Of course, me being as cheap as I am, couldn't justify paying twice as much for essentially the same pump just for the extra holes.
Actually, I bought the Summit brand pump because it's the Holley pump (same casting number and everything) only private labeled and cheaper yet!
No matter how I clocked the pump, the fittings were just in a bad spot-
So I made my own holes.
Part of the problem is that there are only 5 or 6 bolts, which gives very limited options. Some of the other pumps (I think maybe Edelbrock?) have like 12 bolts so you have a much finer adjustment range. Of course, me being as cheap as I am, couldn't justify paying twice as much for essentially the same pump just for the extra holes.
Actually, I bought the Summit brand pump because it's the Holley pump (same casting number and everything) only private labeled and cheaper yet!
I actually bought the Jegs pump, same thing.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
I had the same problem. I used a 90* elbow 3/8" npt on the inlet port and ran the rubber fuel inlet line over the side of the fuel pump and back down into the elbow.
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Brett Foote
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I was just wondering because I use the stock AC-Delco mech pump and it feeds a big hungry 434 at 7500 rpm laping around the track where I have my foot on the floor for long periods of time and never have a problem. I'm actually using the return bypass lines.
I used to run the bigger flow needle and seat to keep the bowls filled on my 5-6 pound return system with 825 CFM professionally setup racing carb.
IMO - high GPH pumps fail because they work harder trying to pump unneeded fuel into a regulated system. You really hear this on electric pumps when they load up because of no demand.
If you look up pounds per hour, bsfc. and Hp. 110 gph could supply over 1200 hp N/A
I used to run the bigger flow needle and seat to keep the bowls filled on my 5-6 pound return system with 825 CFM professionally setup racing carb.
IMO - high GPH pumps fail because they work harder trying to pump unneeded fuel into a regulated system. You really hear this on electric pumps when they load up because of no demand.
If you look up pounds per hour, bsfc. and Hp. 110 gph could supply over 1200 hp N/A
Drifting
Joined: Aug 2005
Posts: 1,443
Likes: 65
From: Wauconda IL
I would agree that 110 GPH is overkill for most applications but then I also believe these pumps are rated arbitrarily.
Given a 3/8" inlet hose from the tank and a 3/8" fuel line up to the carb, once you add in all the restrictions from not only the line itself, but all the bends, elbows, filters and needle/seat assembly, there is NO WAY you could ever push 110 GPH at the 7 or so PSI that they are rated.
Most AC/Delco fuel pumps (mechanical) are rated in the 30-40 GPH range (even the "Chevrolet Performance" pump is rated at 30 GPH @ 7 PSI). My guess is there is no true apples to apples comparison here.
What I've found on my personal vehicles is that any performance Big Block's OEM pump will not be able to keep up at the end of a 1/4 mile if you're running a Q-Jet.
In my experience, the float bowl is too small on the Q-Jet and the pump can't keep up.
As soon as I install a larger mechanical or electric pump, the problem goes away. Installing a Holley with their large fuel bowls also seems to help mask the issue.
I'm not disagreeing that you are able to work with an OEM just fine in your application, I'm just saying a 110 GPH pump is really not 110 GPH.
Given a 3/8" inlet hose from the tank and a 3/8" fuel line up to the carb, once you add in all the restrictions from not only the line itself, but all the bends, elbows, filters and needle/seat assembly, there is NO WAY you could ever push 110 GPH at the 7 or so PSI that they are rated.
Most AC/Delco fuel pumps (mechanical) are rated in the 30-40 GPH range (even the "Chevrolet Performance" pump is rated at 30 GPH @ 7 PSI). My guess is there is no true apples to apples comparison here.
What I've found on my personal vehicles is that any performance Big Block's OEM pump will not be able to keep up at the end of a 1/4 mile if you're running a Q-Jet.
In my experience, the float bowl is too small on the Q-Jet and the pump can't keep up.
As soon as I install a larger mechanical or electric pump, the problem goes away. Installing a Holley with their large fuel bowls also seems to help mask the issue.
I'm not disagreeing that you are able to work with an OEM just fine in your application, I'm just saying a 110 GPH pump is really not 110 GPH.