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Boost reference mechanical fuel pump

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62Cometman
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Joined: Sun Mar 22, 2015 2:41 pm
Location: Lincoln, NE

Boost reference mechanical fuel pump

Post #1 by 62Cometman » Fri Feb 22, 2019 1:32 pm

Hey everyone, i am working on getting my low buck boosted 170 and plan on just boost referencing the mechnical pump, however since my car has the vacuum wipers i figure thats not a possiblity? if it is let me know so i dont have to swap out to a different pump, but i was looking at the pump for the electric wiper cars but this also looks a little different and want to know if the same idea of drilling a hole on the actuated side of the diaphragm and plumbing boost to that hole to increase the psi 1:1. But since this unit looks like the inlet bolts to the bottom idk if there is a different way it has to be done?

electric pump
https://www.rockauto.com/en/moreinfo.ph ... 6036&jsn=9

vacuum pump
https://www.rockauto.com/en/moreinfo.ph ... 47&jsn=435
1962 Mercury Comet 170 ci, Dagenham Trans, 2.83:1 7.25 rear.
She ain't fast but she's fun. 8)

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bubba22349
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Location: Flagstaff, Az. 86005 near the old Route 66

Re: Boost reference mechanical fuel pump

Post #2 by bubba22349 » Fri Feb 22, 2019 2:15 pm

62Cometman wrote:Hey everyone, i am working on getting my low buck boosted 170 and plan on just boost referencing the mechnical pump, however since my car has the vacuum wipers i figure thats not a possiblity? if it is let me know so i dont have to swap out to a different pump, but i was looking at the pump for the electric wiper cars but this also looks a little different and want to know if the same idea of drilling a hole on the actuated side of the diaphragm and plumbing boost to that hole to increase the psi 1:1. But since this unit looks like the inlet bolts to the bottom idk if there is a different way it has to be done?

electric pump
https://www.rockauto.com/en/moreinfo.ph ... 6036&jsn=9

vacuum pump
https://www.rockauto.com/en/moreinfo.ph ... 47&jsn=435


Yes for sure you can boost reference your current fuel pump since it has two separate pump diaframs with the one used only for boosting vacuum for the vacuum wippers. But the question is how good the vacuum wippers are going to work when only hooked up to that fuel pump vacuum sorce, hopefully you don't need to use them much. Good luck :thumbup: :nod:
A bad day Drag Racing is still better than a good day at work!

I am still hunting for a project car to build but with my current low budget it's not looking so good. My Ex- Fleet of Sixes these are all long gone! :bang: 1954 Customline 223 3 speed with O/D, 1963 Fairlane project drag car with BB6, 1977 Maverick 250 with C4, 1994 F-150 a 300 with 5 speed.

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62Cometman
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Posts: 240
Joined: Sun Mar 22, 2015 2:41 pm
Location: Lincoln, NE

Re: Boost reference mechanical fuel pump

Post #3 by 62Cometman » Fri Feb 22, 2019 2:51 pm

Well they barely work to begin with, so not much difference. I plan on changing to electric motor wipers eventually.
1962 Mercury Comet 170 ci, Dagenham Trans, 2.83:1 7.25 rear.
She ain't fast but she's fun. 8)

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powerband
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Location: Mid Hudson Valley - \H/

Re: Boost reference mechanical fuel pump

Post #4 by powerband » Fri Feb 22, 2019 5:50 pm

Depending on what you have planned, most current Blow-Through forced induction setups use a return to tank fuel supply with a boost referenced Bypass regulator. Referenced' mechanical FP may be possible but could limit performance options. Draw-Through turbo setups do not require boost referencing or return to tank regulator.

have fun
"Take time to stop and smell... The roadkill..."

drag-200stang
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Location: Michigan

Re: Boost reference mechanical fuel pump

Post #5 by drag-200stang » Sat Feb 23, 2019 10:24 am

I know people have boost referenced the mechanical fuel pump, but I cannot see It being a good idea...Not sure about the combo pump you have, but on a regular fuel pump there is no seal between the diaphragm rod and the bushing bearing...You will suck oil air out of the crankcase under vacuum and into the intake and blow air into the crankcase under boost...Yes it won't be much depending on the rod to bushing clearance..
I also cannot help think that under long high high vacuum conditions that the high vacuum could overcome the fuel pressure spring and result in low fuel pressure ...I guess that not much fuel would be needed in those conditions.
66 Mustang Coupe
200 turbo w/lenco 4-spd
stock adj. rockers, stock timing set, ARP studs
best 1/4 mile ET 9.85/best mph 139 on 8 lbs progressing to 15 lbs boost
Went 9's when 10's was fast.

guhfluh
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Re: Boost reference mechanical fuel pump

Post #6 by guhfluh » Sat Feb 23, 2019 7:21 pm

drag-200stang wrote:I know people have boost referenced the mechanical fuel pump, but I cannot see It being a good idea...Not sure about the combo pump you have, but on a regular fuel pump there is no seal between the diaphragm rod and the bushing bearing...You will suck oil air out of the crankcase under vacuum and into the intake and blow air into the crankcase under boost...Yes it won't be much depending on the rod to bushing clearance..
I also cannot help think that under long high high vacuum conditions that the high vacuum could overcome the fuel pressure spring and result in low fuel pressure ...I guess that not much fuel would be needed in those conditions.

Inline check valve...
1967 F-250 Crew Cab 2wd, 300 6cyl, T-170/RTS/TOD 4-speed overdrive
240 head, Offy C, EFI exhaust manifolds, Comp 268H, mandrel 2.5-3" exhaust, Edelbrock 500, Pertronix ignitor and coil, recurved dizzy. 200whp/300wtq

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