The Murphy Builders Site

I thought I'd take advantage of the many learned people of the list to get
opinions about using an electric water pump versus a belt driven pump on

Chevy V8. I figure a power loss is going to be a problem for me anyway

my MSD ignition, so losing my source of power would not deter me from
choosing an electric pump. I just have to make sure I don't lose the
source. Anybody have any insight into the reliability of the electric

themselves? If the odds of losing the electric pump due to an internal
failure are at least equal to the odds of breaking a belt, then I'm

to go with the electric pump. One drawback I can think of is less reserve
time on the battery to get on the ground if I lose the alternator.

Mike Kimball
044SR




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Regarding my fuel pump setup, I was planning on gravity feed, maybe with
an
electric pump to help me out with any vapor lock problems. I don't know
if
the electric pump would be any advantage for anything else. Other
airplanes
using gravity feed usually have carburetors below the engine. Since my
carb
is on top of the engine I have 2 or 3 feet less head pressure. I don't
know
whether that's enough to make a difference requiring an electric pump. It
seems like the pressure at the carb would lower as the fuel level in the
tank lowers too but it's been over 30 years since I've had high school
physics so I don't know about that either. Easy enough to check. I can
just get a pressure gauge and measure the pressure at the carb with only a
bit of fuel in the tank. Since my wings aren't on I can do that with a
jerry can. If there's enough pressure at the carb + some margin (say 5
psi)
to run my carb with very low fuel I may forgo using an electric pump at
all.
By the way, a mechanical pump is out of the question. I didn't realize
until the engine was completely built that Rodeck delivers their engine
blocks with the fuel pump shaft hole not drilled through all the way.
Quite
a surprise when I went to mount the standard Chevy fuel pump!

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
rickhm@comcast.net
Sent: Saturday, May 07, 2005 2:02 PM
To: rebel-builders@dcsol.com
Subject: Re: Electric Water Pump?


I don't recall your fuel pump setup, but many V8 installations utilize
dual
fuel pumps and check valves. This could be done with the water pump as
well. This way if you loose a belt, you have the electric water pump as a
backup. If you loose an alternator, turn/leave the electric fuel pump
off.
I design medical equipment and we use this model frequently, it is refered
to as the 2 fault model where you must have 2 failures independant of each
other in order to create a hazard. Again, I am not sure of your setup,
but
in many auto's if you loose a belt you would loose the alternator AND the
water pump which isn't good. In such a setup, an electric water pump with
a
check valve would keep the engine cool while you ran on battery to find a
place to set down.

Rick Muller
SR070

-------------- Original message --------------

I thought I'd take advantage of the many learned people of the list to
get
opinions about using an electric water pump versus a belt driven pump on

my

Chevy V8. I figure a power loss is going to be a problem for me anyway

with

my MSD ignition, so losing my source of power would not deter me from
choosing an electric pump. I just have to make sure I don't lose the
source. Anybody have any insight into the reliability of the electric

pumps

themselves? If the odds of losing the electric pump due to an internal
failure are at least equal to the odds of breaking a belt, then I'm

inclined

to go with the electric pump. One drawback I can think of is less reserve
time on the battery to get on the ground if I lose the alternator.

Mike Kimball
044SR




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Regarding my fuel pump setup, I was planning on gravity feed, maybe with an
electric pump to help me out with any vapor lock problems. I don't know if
the electric pump would be any advantage for anything else. Other airplanes
using gravity feed usually have carburetors below the engine. Since my carb
is on top of the engine I have 2 or 3 feet less head pressure. I don't know
whether that's enough to make a difference requiring an electric pump. It
seems like the pressure at the carb would lower as the fuel level in the
tank lowers too but it's been over 30 years since I've had high school
physics so I don't know about that either. Easy enough to check. I can
just get a pressure gauge and measure the pressure at the carb with only a
bit of fuel in the tank. Since my wings aren't on I can do that with a
jerry can. If there's enough pressure at the carb + some margin (say 5 psi)
to run my carb with very low fuel I may forgo using an electric pump at all.
By the way, a mechanical pump is out of the question. I didn't realize
until the engine was completely built that Rodeck delivers their engine
blocks with the fuel pump shaft hole not drilled through all the way. Quite
a surprise when I went to mount the standard Chevy fuel pump!

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
rickhm@comcast.net
Sent: Saturday, May 07, 2005 2:02 PM
To: rebel-builders@dcsol.com
Subject: Re: Electric Water Pump?


I don't recall your fuel pump setup, but many V8 installations utilize dual
fuel pumps and check valves. This could be done with the water pump as
well. This way if you loose a belt, you have the electric water pump as a
backup. If you loose an alternator, turn/leave the electric fuel pump off.
I design medical equipment and we use this model frequently, it is refered
to as the 2 fault model where you must have 2 failures independant of each
other in order to create a hazard. Again, I am not sure of your setup, but
in many auto's if you loose a belt you would loose the alternator AND the
water pump which isn't good. In such a setup, an electric water pump with a
check valve would keep the engine cool while you ran on battery to find a
place to set down.

Rick Muller
SR070

-------------- Original message --------------

I thought I'd take advantage of the many learned people of the list to get
opinions about using an electric water pump versus a belt driven pump on

my

Chevy V8. I figure a power loss is going to be a problem for me anyway

with

my MSD ignition, so losing my source of power would not deter me from
choosing an electric pump. I just have to make sure I don't lose the
source. Anybody have any insight into the reliability of the electric

pumps

themselves? If the odds of losing the electric pump due to an internal
failure are at least equal to the odds of breaking a belt, then I'm

inclined

to go with the electric pump. One drawback I can think of is less reserve
time on the battery to get on the ground if I lose the alternator.

Mike Kimball
044SR




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Regarding my fuel pump setup, I was planning on gravity feed, maybe with

electric pump to help me out with any vapor lock problems. I don't know if
the electric pump would be any advantage for anything else. Other

using gravity feed usually have carburetors below the engine. Since my

is on top of the engine I have 2 or 3 feet less head pressure. I don't

whether that's enough to make a difference requiring an electric pump. It
seems like the pressure at the carb would lower as the fuel level in the
tank lowers too but it's been over 30 years since I've had high school
physics so I don't know about that either. Easy enough to check. I can
just get a pressure gauge and measure the pressure at the carb with only a
bit of fuel in the tank. Since my wings aren't on I can do that with a
jerry can. If there's enough pressure at the carb + some margin (say 5

to run my carb with very low fuel I may forgo using an electric pump at

By the way, a mechanical pump is out of the question. I didn't realize
until the engine was completely built that Rodeck delivers their engine
blocks with the fuel pump shaft hole not drilled through all the way.

a surprise when I went to mount the standard Chevy fuel pump!

Mike

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
rickhm@comcast.net
Sent: Saturday, May 07, 2005 2:02 PM
To: rebel-builders@dcsol.com
Subject: Re: Electric Water Pump?


I don't recall your fuel pump setup, but many V8 installations utilize

fuel pumps and check valves. This could be done with the water pump as
well. This way if you loose a belt, you have the electric water pump as a
backup. If you loose an alternator, turn/leave the electric fuel pump off.
I design medical equipment and we use this model frequently, it is refered
to as the 2 fault model where you must have 2 failures independant of each
other in order to create a hazard. Again, I am not sure of your setup, but
in many auto's if you loose a belt you would loose the alternator AND the
water pump which isn't good. In such a setup, an electric water pump with

check valve would keep the engine cool while you ran on battery to find a
place to set down.

Rick Muller
SR070

-------------- Original message --------------

I thought I'd take advantage of the many learned people of the list to

opinions about using an electric water pump versus a belt driven pump on

my

Chevy V8. I figure a power loss is going to be a problem for me anyway

with

my MSD ignition, so losing my source of power would not deter me from
choosing an electric pump. I just have to make sure I don't lose the
source. Anybody have any insight into the reliability of the electric

pumps

themselves? If the odds of losing the electric pump due to an internal
failure are at least equal to the odds of breaking a belt, then I'm

inclined

to go with the electric pump. One drawback I can think of is less

time on the battery to get on the ground if I lose the alternator.

Mike Kimball
044SR




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-----------------------------------------------------------------

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