Fuel pump lobe modification.

Hamilton Cams

Hamilton Cams

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Jun 28, 2007
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I know a lot of people here are wanting to use their stock fuel pump with a pretty hot setup p-pump. I have not messed with it much in the past, but with all of the talk of making big power on a stock fuel system. is anybody interested in a modified fuel pump lobe with more lift or multiple events? I believe we are at a .250" lift lobe.

I know we could get a little bit more out of it. Just gauging the interest.

Zach
 
I always wondered if 2 lobes 180* apart would double the output...
 
This is an interesting idea. I'm curious how well it would work with two lifts vs. the one. My first thought is that you would need a heavier return in the pump plunger.
 
I have seen injection pump cams that had two lift pumps as opposed to the one. Worst case scenario, I could give a lower base circle by .075" and higher peak by .075" This would at least give you .150" more stroke and a little bit more volume.

On our next batch of custom grinds, we will at least have more stroke, if not two lobes.

Zach
 
another thing, the first gen's have to be able to handle whatever modification we do. How many first gen's are running a p-pump style lift pump?
 
I think it would be a great idea to try. I went out and looked at my spare cam in the shop and there appears to be plenty of room for a second lobe and I'll retract my original idea of needing a stronger return spring in the lift pump.
 
Would the plunger return fast enough for more lift or would it just float?

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chevota84 said:
Would the plunger return fast enough for more lift or would it just float?

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Click to expand...

That was my original thought but, I think if that was an issue we would have seen evidence of that problem on the higher rpm engines.
 
Hamilton Cams said:
another thing, the first gen's have to be able to handle whatever modification we do. How many first gen's are running a p-pump style lift pump?
Click to expand...

I am for one. Also just purchased an air dog that I haven't installed yet. If this had been on the radar earlier I may have held off on that purchase since the engine is coming out for a cam swap in about a month.
 
Smokie Okie said:
That was my original thought but, I think if that was an issue we would have seen evidence of that problem on the higher rpm engines.
Click to expand...

I swear I read every post and I completely missed your question about the return spring lol.

I like the idea, nothing beats the plunger pump for reliability.

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Hamilton Cams said:
another thing, the first gen's have to be able to handle whatever modification we do. How many first gen's are running a p-pump style lift pump?
Click to expand...

FWIW, for a VE equipped truck to run an actual P-pump lift pump, it has to be regulated down anyways. I'm not sure how the lower pressure piston pump, like I have, would handle such a thing.

I figure if a VE truck is at the point that it's getting one of your cams, the feed system has been upgraded to at least a regulated P-pump setup anyways, if not electric.

$.02
 
would it be possible to do this for a second gen truck with a VP pump and install a pressure regulator with a return line and a check valve before the pump to prevent drain back for start up. would it flow enough to cool the vp and retain enough fuel for start up?

I would love to get rid of the electric pumps on the VP trucks. What do you think?
 
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Just a stock plunger pump setup is enough to support most VP trucks.

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On the 1st Gen guys running the low pressure one, some have found they can sucks those dry. BC847 took one apart and found not only a lighter return spring (for the pressure) but also a smaller bore. The way some have combatted (sp?) it was either buy a 2nd Gen high pressure pump and swap springs or regulate the 2nd Gen one.

I hope this helps you some. I will be running the 2nd Gen lift pump if I can.
 
i would think that i might be better to run a bit more lift on this as the longer stroke would give more duration and would probably work better for the higher rpm guys instead of essentially doubleing the rpm.. unless somehow the piston pump would be more efficient with a bit less stoke and doubleing it with two lobes.. it just seems that at some point it would start to cavitate or even like suggested earlier start to float.. just my thinking out loud..
 
Will the pump even allow that much more stroke?

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i seem to remember that the arm would move something like a half inch at the lobe area.. i guess i should remember that the cam is turning half the engine rpm also..
 
What's wrong with the stock one, I've been using it for 10 years now and no issues.

Jim
 
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