FrontEngineDragsters.Org Forum
Technical => Spud Miller's Cave => Topic started by: DeSoto on June 30, 2014, 03:02:36 PM
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Hello, can or does anyone still run a scott.
I am wanting to use this on a 63-66 era Desoto powered fed.
It seems it isn't common enough to warrant much press on the net. At least none from a
experienced users perspective. And I have been digging for quite sometime. I am hoping it can be more than just a novelty.
This is my first fed build so all advise welcome. Lots to learn.
Thanks for all your contributions here.
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It looks like it worked pretty good on Mad Max!
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Do you have the Scott fuel pump that goes with it???
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We've worked on a few of those. You really need the pump and metering valve in order for it to work as intended. You could set it up with a more modern metering valve and nozzle setup though and just enjoy the cool look of that scoop.
The biggest problem we had working on them was finding seals and things to cure leaks. It's all really old, non-standard stuff.
Spud
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Thanks for the input guys.
Unfortunately my searches on this injector hasn't turned up much more than
It being used as a mad max movie prop. Not much help for my efforts to learn
how to get it back in use on a fed.
I did not get the scott pump with it and figure there is little chance of finding one to get it
back to its original configuration. I read somewhere racers would change them for being problematic and has been done to this one also.
It has been drilled and tapped for 8 nozzles and must have been run with a hilborn
pump sometime along the way.
Spud, I don't see a place for any seals on this but a gasket between scoop and butterfly base.
The butterfly shaft doesn't even have bushings. Looks to be a 1/2" steel shaft fit right to the
aluminum casting. It does still fit nice with out any apparent wear and may not leak much in this area at all.
The butterfly's do seem to fit the housing as intended and appear untampered with. They are somewhat crude if I was to compare them to a Holley throttle plate with the ground bevel seal to the bore. (no bevel on this) Even completly closed you can see a little light around them. And slightly more in the corners but I believe this is how it was fit when built. Not sure if this will be a problem as I have no other injector experience to compare this to. They do move bind free just slightly snug
and I believe a drop of oil at each end will take any resistance out of it. This hasn't been used for many decades.
I don't know enough about what I am looking at when it comes to the nozzles and metering to give
a good decription so I put up some photos after I resize them.
My intentions are to use this on a cackle project as I don't want to use a updated chassis style.
I appreciate any input and would hope to end with this old part being able to be used in some workable configuration.
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Another thing I should have mentioned is the 8 nozzle ports have been moved to below the plates like a hilborn and the original Scott above plates plugged. If I had to guess I would say the nozzles
are homemade by pressing a short piece of aluminum rod into a brass fitting. A hacksaw cut half way through and drilled from the inside of fitting to the cut made with the saw. They look to be drilled about .040 without measuring them.
All the nozzles are fed by rubber hilborn style lines and come out of a added metering or possibly just a plain fuel block. This block is fed by a little larger rubber line that is attached to the scott block that is cast into the main throttle plate casting.
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They work fine for Cackleing. Really need to locate the pump, the whole system revolves around it. The pumps were refered as "washing machine" type as it was just a crank driven impeller and did not rely much on pressure as it did volume of fuel. The blades dont need to be perfect or seal as some amount of air is needed to get into the engine to idle. 1,000's of injectors have been/still do made without bushings/bearings around the throttle shafts, and in fact when exsesive play becomes a problem , its the steel shaft that is usually worn down and not the alu.
If you go to www.cacklefest.com and in the parts for sale section --Bill Turney has some Scott pieces(includeing pumps) for sale. Also (its hard to read and you have to enlarge it) is the instruction sheet and the explination of how the whole thing is designed to work.
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Dreracecar, I had a look at Bill T. Scott collection on the site you posted.
I gathered that Scott has made at least 3 different sized injectors of this design.
The two he has pictured have considerably smaller throttle plates and have a rounded
shape to them. The model I have is rectangular and the full length of a 671 opening. Appears to
be a way to make them as large as they could with the blower case top opening size.
My guess would be a newer model. Mine also has M/T cast into it. So mine must have
been sold through Mickey Thompson. Guess?
I did see the pumps he has pictured. I couldn't make out the instruction sheet. I think I will
try and contact him to see if he has anything spare laying around that would work to get mine
back to original. If not I will have to try it out in its currently converted to hilborn style.
Thanks for the input.
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Scott did private label the injection to M/T. Air going thru the injector (at our level) does not know or care about the shape of the throttle blades, but in order to convert to a Hilborn/Enderle type injection, a change in the BV is nessasary because they opperate at different pressure and volume. The newer pumps work as positive displacement and require checks to return excess fuel wheras the Scott works by cavitation once the fuel requirement is met or restricted. All that is needed for the Scott is just the one feed line. I prefer the Enderle BV but for your needs the Hilborn BV is more to the Scott shape and size to fit better.
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Thanks for that info, is the barrel valve pictured a hilborn part or? Hope someone here might be able
to I'd it. I looked it over and found no #s or markings to track. I would guess someone did have it all
working at somepoint 30 or more years ago as it was all assembled when I got it. I didn't get a pump with the setup. But I have one that may be able to be used.
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What is pictured with the lines is a distribution block and not a BV, the fuel from the BV goes to the dist block which then send the fuel to the nozzles. The fuel metering valve is at the front of the injector and is opperated by the throttle shaft.
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Thanks again. I think I'm with you now. So the barrel valve used is in the scott casting.
The barrel valve would have to be changed to the hilborn type to have been used with a
hilborn pump or the scott barrel valve would have been retained if they stayed with the scott
pump.
I am beginning to think it wasn't run with a hilborn pump and they just added the block, extra nozzles and lines for some reason?
If I take the barrel valve out and post a pic. Would you be able to tell me if it is a Hilborn or correct for the Scott.
Sounds like this is very important and would give me a clue as to how it was run last.
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Did a little surfing on the web
http://www.scottfuelinjection.com/pump/ (http://www.scottfuelinjection.com/pump/)
Scott Centrifugal Pump
Why was the Scott centrifugal pump superior to others ? Here’s how
Scott explained it on the cover of his catalogues:
Scott Fuel Injection uses a completely different type of pump than any other
injection system on the market. Other Injectors use a positive displacement type
pump, with return lines, etc. Scott uses a diffuser centrifugal type pump (no return
lines), which has a much wider pressure range than the positive type pump. It also
can pump twice the volume.
The reason we want a wide pressure range is on a blown engine for example, with
say 300 cu. in., turning 2000 RPM, there is no blower boost yet, so in order to have
a fuel air ratio of 12 to 1, you need 11 GPH of gas, and with the engine turning 7000
RPM and 15 lbs. of boost, for a fuel air ratio of 14.3 to 1 you need 63 GPH. In order
to achieve this the pump must pump 9 times the pressure at 7000 RPM than at 2000
RPM because a jet or nozzle will allow .6 times the volume to pass when you double
the pressure. This is due to a pressure drop through the jet or nozzle.
The Scott pump is designed to give a fuel pressure of 8 lbs/sq. in. at 2000 RPM
(when driven at crank speed) and about 92 lbs. at 8000 RPM. This rate of pressure
build up is a little less than the square of RPM; but the pressure curve is typical
of a cetrifugal pump. Scott pumps use no by-pass return lines. All the pump pressure
goes right to the nozzles. Result is a fuel flow that is nearly proportional to RPM,
so the cylinders get virtually the same volume of fuel per suction stroke at 2000
RPM as at 6000 RPM or 7000 RPM. Load control is accomplished in much the same
way as the other competition systems – that is, fuel flow to the nozzle passes through
an orifice and metering valve assembly that is linked to the throttle pedal. This cuts
down the pressure at any given RPM as you close the throttle. The valve is operative
over the full range of butterfly travel.
The graph below speaks for itself !
(http://www.scottfuelinjection.com/wp-content/uploads/2012/03/graph.jpg)
The Scotts also sent me an article from Dr. Robert H. Goddard (volume 3: 1938
-1945) which goes into great detail about how the cetrifugal pump is superior due
to it’s high volume and dependability. E-mail me for a copy of this if you like. (info@madmaxcar.com)
http://www.madmaxparts.com/ (http://www.madmaxparts.com/)
(http://www.madmaxparts.com/images/600_SCOTT1.jpg)
This is a look alike EFI unit (http://www.scottinjection.com/index.html?show=historical)
I found no pictures of the pump, do not believe this is correct
(http://www.jalopyjournal.com/forum/attachments/img_0013-jpg.928501/)
Best I can tell the pump was off the crank
(http://www.scottinjection.com/rattler-2.jpg)
here is a post on the HAMB
(http://www.jalopyjournal.com/forum/threads/scott-fuel-injection.446965/)
A little more poking around might find additional stuff.
(http://www.jalopyjournal.com/forum/attachments/inj-hat-jpg.1351465/)
(http://www.jalopyjournal.com/forum/attachments/inj-hat-2-jpg.1351466/)
(http://www.jalopyjournal.com/forum/attachments/inj-hat-3-jpg.1351467/)
(http://www.jalopyjournal.com/forum/attachments/inj-hat-1-jpg.1351528/)
another HAMB post
http://www.jalopyjournal.com/forum/threads/scott-injector-hat-need-a-photo.599907/ (http://www.jalopyjournal.com/forum/threads/scott-injector-hat-need-a-photo.599907/)
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You cannot use the Scott metering valve with the Hilborn pump. Metering valve and barrel valve ,although have the same purpose, they are not the same. Glenn provided a pic of an oval blade injector with what appears to be a BV off to the side and linkage to the throttle shaft. This is the correct way to construct a system if one plans to use the Hilborn pump.
Glenn that is the correct pump picture, the best way to describe it as a "washing machine pump" and only has one moving part and that is a vaned impeller
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You could easily get hook on this, so c-101 or c-202 pump.
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That is a lot of information there.
I would like to run this with the scott style pump but as far as I can tell they are
next to impossible to get your hands on. I don't think there is a workable substitute.
It took me two years of looking to find this incomplete injector and it wasnt really what could be called reasonably priced because there are not many of these out there to be found.
I would guess if I keep looking I may be able to come up with a old scott pump in a few years maybe. I would call it lucky but not likely.
I think for this reason I believe I want to pursue the hilborn pump route to get this going with parts that can be had easily.
So to do this from what I have gathered I will need the following...
A hilborn style pump (hilborn150)
A fuel shut off (doesn't matter brand)
A barrel valve (Enderle side mounted) scott metering valve on injector body no longer used
A bypass line back to tank
Am I missing anything here?
Do you guys think this is a good plan or should I continue searching for the correct pump?
I am concerned I may never find one.
What would you do to get this working again? Although I know it would make more sense to most racers, I don't want to hear buy a new hilborn set up.
Using a vintage part is the main objective for me.
You guys have been contributing alot to help me understand what options i have to sort through my problem and I believe I understand most of what has been posted here. Many thanks, and keep your thoughts coming.
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Enderle BV will be hard to adapt because of its size and the placement of the spool and fittings. By using the Hilborn BV off the 4 port uprite injector the shaft araingment is very simular and very easy to adapt to
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Thanks for the correction and tip, Dreracecar.
Is this barrel valve something I should contact hilborn and buy new or is this a part that finding
used could work out OK.
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Chances are you will not find a used unit or if you did I would be suspect of its condition.
BV and componants will run you say around $300/$400 and then you will have to make a plate that goes between the injector and blower to mount the BV. then you will have to machine the MV off the front of the Scott to get access to the throttle shaft. You may have to machine a little off the bottom (or raise)of the scoop for linkage clearence.
I have the ability to do this for you if you feel overwelmed or do not have access to the equip, cost is the parts plus time (approx $300 lbr) but you will have workable Scott system. Your other alternative is to find a Scott pump and figure out a crank drive for it.
let me know if I can help
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couldn't the linkage be picked up of the rear of the scoop,
(http://www.hotrodscustomstuff.com/OLD_SITE/Cars/Mad%20Max/mad-max-03-07.jpg)
and a enderle square barrel valve
(http://www.goodvibesracing.com/Product-Scans/E-4023.gif)
If you made the right bracket, it looks like you could mount the Square valve directly in back of the shaft coming out of the hat and use a simple coupler to attach the two together (sleeve with two Allen bolts).
Crower barrel valve on the rear of a crower hat with linkage
(http://i72.photobucket.com/albums/i167/shakeypuddin55/DSCN1364.jpg)
found this picture with scoot scoop but enderle injector (with "K" valve) under it (just a thought)
(http://www.racecarparts.com/images/listings/287_l.jpg)
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Anything can be done, its a matter of cost -availability-fit.
Using current parts on a old casting, and the ability to get the basic set up/nozzles and lines fits those issues with the least amount of effort and cost.
Enderle will not work because of size and shape plus fitting placement, so it will have to be placed really off to one side and look like crap
Enderle "K" valve is expensive, and have extra ports and checks that wont be used.
Crower (RONS FI) is pricey and one still has to adapt.
My way starts with new parts from that era that a racer could have done that conversion back then.
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I will have a little more time after work to go over all your post. I kind of quickly skimmed them for now. I do like the sound doing this in a way that could have been done back in the day.
I have a Joe hunt magneto that stands up 3 1/2" higher than usual and is very close to the blower case. Less than a 1/2" clearance. A hilborn right angle pump drive is the reason for this extra height. I can use this drive to run the pump if needed. If I take the angle drive out I would have to change to a longer shaft in the magneto to reach the gear.
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Another thing I should have mentioned is my blower manifold is not finished yet so if I needed a little more height in the rear to keep things off the magneto I could raise the blower a bit. I was trying to keep it as low as possible but if room is needed.