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Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: kenzen ()
Date: April 21, 2020 07:00PM

alphasud Wrote:
-------------------------------------------------------
> Working on Beetles we have to shim between the pump and the Bakelite adapter to adjust the fuel pressure. I thought the big issue with the mechanical pumps was there is nobody who makes a good diaphragm material to cope with today’s fuels.

The gasket materials are not a problem - modern materials can take the ethanol, but an older "NOS" pump (if it hasn't dried up on a shelf) may have problems wiht the ethanol. The actual problems are the screws loosen up (solved with longer screws installed with lock nuts from the other side - #10-32 x 2") and the base plates warp causing leaking past the gaskets. The later problem here is the main challenge - I replaced the new thicker and heavier base plates with thin aluminium ones from older pumps to avoid this. I can't say that the warping problem with the thicker plates might be avoidable if the screws are kept tight per the above mod, but it might be possible a loosened pump body can't dissipate heat like it needs to.

kenzen
66 Monza Coupe 110/PG
Bel Air, MD

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: kenzen ()
Date: April 21, 2020 07:04PM

azdave - very clever! Even at a very low spring tension giving a low output pressure, the displacement of the pump is fixed with the stroke length of the push rod, so the volume rate capacity of fuel delivery would not be compromised unless otherwise restricted (e.g. carb fuel filters dirty).

kenzen
66 Monza Coupe 110/PG
Bel Air, MD

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: Vairismo ()
Date: April 21, 2020 09:09PM

Have you tried ordering 3" schedule 160 aluminum pipe from a metal supply place? That would seem to fill the bill, no idea if there might be a minimum order or not, but worth a look. Just sayin'.

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: American Mel ()
Date: April 21, 2020 09:19PM

Vairismo Wrote:
-------------------------------------------------------
> Have you tried ordering 3" schedule 160 aluminum pipe from a metal supply place? That would seem to fill the bill, no idea if there might be a minimum order or not, but worth a look. Just sayin'.


Schedule 160. eye popping smiley
I am guessing that milling out of solid stock is going to be cheaper!

-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
WA. state, 1 mile south of the Canadian border,
I am not at the end of the world, but you can see it from here.
Have; '66 Monza Coupe - 140, 4-spd. Daily driver beater
'67 Monza Vert. - 140, 4-spd. Daily driver beater
'67 A/C Moredoor Monza
Have had; '61 Monza coupe, 80hp, PG
'62 Monza Wagon, 4spd.
'63 Spyder,
'65 Corsa
.
non-vair
'04 Dodge Cummins Quad Dually, approaching 400K
'03 Honda Del Sol
17'Terry

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: April 22, 2020 05:19AM

Brizo Wrote:
-------------------------------------------------------
> If you want to show off your machining skills some more, carve out a new hard aluminum pump base that wont warp.

I have turned a few bases to make them flatter but won't be making new bases. I still have a few of the old ones around in my stash. I


Vairismo Wrote:
-------------------------------------------------------
> Have you tried ordering 3" schedule 160 aluminum pipe from a metal supply place?

Yes. Won't work. The wall thickness is almost 1/2" like I need but the OD is 3.5" so out of range. I looked at metric too. Ideally, I need no less then 3.125" OD and 2" ID. I can cheat on the ID a little and maybe go to 2.125". Right now, the best option is drop-off's I've found on eBay.


For those wondering, I've considered 3D printed but not going there yet. I think it could be done and I only need an excuse like this to buy one. smiling smiley

Thank again for the feedback!

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: doug6423 ()
Date: April 22, 2020 10:55AM

If you do make them I’d be interested also.
Thanks,

Doug
65 Monza
Cincy, OH

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: cnicol ()
Date: April 22, 2020 12:45PM

Ingenious and a nice piece of work! I wonder if a calibrated spring would be more cost effective? A spring supplier can make springs to any specification.

Craig N. Coeur d'Alene ID.
66 Black Monza 4dr, 4.2L V8 49k
61 Seamist Jade Rampside 140 PG
60 Monza coupe (sold, sniff sniff)
66 Sprint Corsa convt - First car! Re-purchased 43 years later
2+2 gnatsuM 5691

+17 Tons of parts

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: April 22, 2020 02:24PM

cnicol Wrote:
-------------------------------------------------------
> Ingenious and a nice piece of work! I wonder if a calibrated spring would be more cost effective? A spring supplier can make springs to any specification.

Thanks. I would agree with the calibrated spring solution except that there are factors the spring can't compensate for when you have simple, mass produced pumps like these. Check valves are not always perfect, diaphragms are not always soft and pliable, small stroke length variances might even be an issue if manufacturing tolerances are too wide.

A preset spring can't "know" what those variables will be in advance or in the future. I mostly see two different spring heights in my parts bins and that itself has been explored pretty well by kenzen in his very detailed "fuel pump observations" thread. My idea allows for using whatever version spring you have and still lets you set the pressure where you want it and re-set it again later if you please.

I think pump manufacturers are trying to keep the output pressure on the high side because for them, it is better to be too high than too low. I want fuel pressures to be no higher than needed, therefore extending the pump life and also ending issues with overpowering the float valve and the problems that leads to.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: jimc ()
Date: April 22, 2020 04:24PM

Great idea Dave and your usual quality oriented solution.

Jimc
1965 Corsa Coupe, two owner history


HACOA Member
CORSA 2017 Concours Senior Gold Award
AACA 2015 Award

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: Vairismo ()
Date: April 22, 2020 06:43PM

American Mel Wrote:
-------------------------------------------------------
> Vairismo Wrote:
> -------------------------------------------------------
> > Have you tried ordering 3" schedule 160 aluminum pipe from a metal supply place? That would seem to fill the bill, no idea if there might be a minimum order or not, but worth a look. Just sayin'.
>
>
> Schedule 160. eye popping smiley
> I am guessing that milling out of solid stock is going to be cheaper!


Never know until you ask. What I saw was 6061, might find leftovers / scraps and also would depend on the expected volume to be made. Wall thickness of .43something IIRC.

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: April 22, 2020 07:23PM

American Mel Wrote:
-------------------------------------------------------
> I am guessing that milling out of solid stock is going to be cheaper!


Mark Twain quote, "To a man with a hammer, everything looks like a nail.

I have a lathe so everything around here gets spun 'round and 'round. grinning smiley


Did 13 hours at work today then came home and made #3.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Attachments:
Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: jjohnsonjo ()
Date: April 23, 2020 05:37AM

Did you consider making a mold and using high temp high strength epoxy ?

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: April 23, 2020 06:01AM

jjohnsonjo Wrote:
-------------------------------------------------------
> Did you consider making a mold and using high temp high strength epoxy ?

I worry about using anything that might compress or deform even the slightest bit due to heat or long-term compressive forces. That is why I'm not looking at 3D printing or resin molding until later. Any material that might allow the stack of pump components to relax tension could lead to leaks.

For now, metal is my choice until I can prove this is worth making many more. I'll keep testing and do trials with aluminum.

I'm thinking of doing a quick video over the weekend to show the assembly and operation.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: JimBrandberg ()
Date: April 23, 2020 06:02AM

I did some rather crude testing of fuel pump springs in the drill press with a kitchen scale. A very small amount of change in wire diameter, number of turns and free length makes quite a difference in spring weight and performance when it comes to fuel pressure.
I shopped with spring manufacturers online charts and called a few but didn't find anything close. I certainly wasn't going to make the financial commitment to have anything made.
There's a lot of straightforward information available for straight springs but tapered springs not so much.
There's other variables in the fuel pump that affect fuel pressure. The relationship between the locating hole and the end of the rod being just one.
Being able to adjust the effective length of the spring is a cool idea and I applaud the effort. I hope it works out and it's a novel approach I never thought of.

Jim Brandberg
Isanti, MN
CorvairRepair.com






Edited 1 time(s). Last edit at 04/23/2020 06:05AM by JimBrandberg.

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: Grandpacorvair ()
Date: April 23, 2020 06:08AM

Quote
Azdave
I'm thinking of doing a quick video over the weekend to show the assembly and operation.

thumbs upthumbs upthumbs up

Kerry Borgne
Birmingham, Michigan

1963 Spyder Convertible

Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: April 23, 2020 07:54AM

JimBrandberg Wrote:
-------------------------------------------------------
> I did some rather crude testing of fuel pump springs in the drill press with a kitchen scale.....

> I hope it works out and it's a novel approach I never thought of.

Much thanks to you and kenzen because I had a lot of fuel pump posts from the two of you going through my head when this idea hit me.

When I do the video, I'll also show the first version I built using spare parts from a junk 1960 pump. That one is still in use on my 66/140 and I can change the fuel pressure with a push of the finger.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: May 08, 2020 05:52AM

Yes, I'm still playing around with this project. I've been putting the miles on the test mule and closely watching the fuel pressures under lots of various conditions.

I bought a few more new pumps to disassemble/test and can pretty reliably predict their output pressure by performing a quick bench test before they are installed.

One thing I have noticed in all the tests is that the pressure drops about 1 PSI after the engine gets really hot. I'm guessing the rubber membrane is more flexible when it is warm and therefore provides less help to the function of the spring. This only gave me trouble once when I set the cold fuel pressure at 2 PSI. With a hot engine and warm fuel pump, I was probably running well below 2 PSI when at the end of a long hard pull on an uphill freeway entrance in 4th gear the engine coughed from the fuel bowls running too low.

When I set the cold fuel pressure to 4 PSI I'll see it drop to 3 when it's good and hot but cannot get the coughing to repeat on that same freeway entrance ramp test. One good fortune for collecting accurate data on this project was finding a NIB Dwyer Minihelic 0-6 PSI pressure gauge earlier this year. Found it at Goodwill of all places. $3.99 after my senior discount. smiling smiley

For making the extender rings a little quicker, I found a place selling pre-cut aluminum discs and with the help of a 2" annular cutter I'm saving some time on the lathe.

The more play with these the more I realize that having a screw or bolt to fine tune the pressure is not really critical. Set the pressure near 4 PSI on a cold engine and forget it. I can't see most people ever needing to dial it up or down a half PSI but I can still provide a modified cover if they wanted that. Everyone else could just change the shim under the top cover if they felt the need to adjust the pressure sometime later.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: jjohnsonjo ()
Date: May 08, 2020 05:59AM

Hi Dave, I know your not running a turbo, but you do live in a warm climate. My pump is clearly the warmest after 15 minutes of engine off heat soak, especially if I just got off a highway.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa


Re: Adjustable Pressure Mechanical Fuel Pump Experiment
Posted by: azdave ()
Date: May 08, 2020 09:26AM

jjohnsonjo Wrote:
-------------------------------------------------------
> Hi Dave, I know your not running a turbo, but you do live in a warm climate. My pump is clearly the warmest after 15 minutes of engine off heat soak, especially if I just got off a highway.

Thanks. Yes, we've been into the 105-107F range lately but I still drive the Corvair quite often. I should fix the A/C and really raise the engine temps. smiling smiley

Just for giggles, I plan to install a few thermocouples in one of my pumps to see how hot they get on a road test. Probably useless info but gives me a mental break from current events.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



Fuel Pump Experiment -More than you wanted to know. smiling smiley
Posted by: azdave ()
Date: May 11, 2020 01:19PM

I tested a few more fuel pumps on Saturday. I get the same results after comparing four pumps that as I mentioned earlier, the pressure drops about 1.0-1.5 PSI from when they are cold to when they are hot. No big deal but interesting to note.

While I was at it, I placed two thermocouples into a fuel pump body during one test run. One was in the base and the other was in the center section that holds the check valves. Some where are suspect that a temperature difference in the parts might be leading to warping over time. This is not enough info to draw any conclusions if that is true or false but it was interesting for me to test while I was at it.

The highest differential I saw between the two parts was 6 degrees but most often 3-4 degrees. Less than I would have guessed. The overall temps of the pump were not unexpected including the hot soak high of 165F.

Dave W. / Gilbert Arizona
65 Corsa 140/4
66 Corsa 140/4
66 Corsa 140/4 w/factory A/C
66 Corsa 455 Toro V8
65 Monza Convertible 110/4
66 Monza Convertible 140/4 A/C
65 Monza 4DR 140/PG w/factory A/C
65 Monza 4DR EJ20T/5



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