My scout drinks fuel

F

fireride

Member
I need some expert help on my Scout, heres the rundown.

72 sii 345, holly dist. Points, 2300c carb #51mj, auto, all ignition appears stock. The Scout was new to me in oct. One of the first things I did was rebuild the carb. (it was leaking) unfortunatly I did the rebuild before I had educated myself on the correct kit to use. I used a carquest generic kit with a new power valve and crappy float. After the rebuild it ran good but seemed Rich, has a decel backfire in the exhaust and smells Rich. Well, I didnt know how Rich until I finally ran a couple tanks of fuel and checked the mileage. 7.3 is the best ive gotten. I also have checked points gap, timing 4 deg btdc, cap and rotor look good and plugs are new and gapped withing speck. Choke opens fully at operating temp.

I am thinking the power valve is not working and dumping fuel all the time. Is it possible to have the wrong gaskets on the metering block and blocking vacum to the valve? I know I need to pull the carb and check the valve but looking for any other things I May hve missed.
Ps the float is set just below the the sight opening, mixture screws set for a smooth idle.

Ive tried to elminate all possibilities before posting, hoping for some guidance on my theory. Down deep I feel like the right thing to do is order the correct kit power valve and brass float and start over with the right shiat!!

Thanks for the help scott
 
I think you've already identified the problem and the proper course of action. Use of any other kit besides a Holley to refurb a 2300 is a recipe for failure. And it is absolutely possible to get a gasket mismatch which can create all sorts of havoc. There are so many variations of these mixers that no readily available trick kit can cover every single possibility. Hopefully you were able to save the original gaskets for comparison. Since you have to bust this pig apart again, might as well soak all the hard parts in crc tyme carb soak according to the instructions on the container.
 
Thanks, I think I did keep the old gaskets but, the gasket I replaced it with matched what I took out. The problem is I have no history from the po. I never ran enough miles before rebuild to know if the problem already existed. Where is the best place to buy the holly kit. Is there a kit # that has what I need in it or does it have multiple gaskets in it as well?
 
Scott - one thing I must ask: how are you calculating fuel mileage?
If you're using the odometer, are you sure it is accurate? I have also found that if you use a small distance, such as less than 100-150 miles, there is more chance for variables.

I have used a gps unit to verify the accuracy of my speedometers/odometers. I also use trips of 150+ miles to calculate my best fuel economy situations. And I try to refill the fuel tank the same way every time I anticipate calculating fuel economy.
 
Without actually seeing all components of the carquest kit you used, I have no idea as to what parts might have been correct and what parts might be wrong for your carb application.

The hly 37-1543 will have a few parts that are not used on that particular list number, but all parts needed to rebuild that carb will be inside the package.

Overall, for the Holley modular carbs there are several variations of the main body, metering body, and fuel bowl gaskets. And the aftermarket power valves in those kits I've always found to be crap anyway. Same for the small circular gasket used with the power valve, it must be the correct type.

A Holley power valve May be tested as shown in this thread:

http://www.forums.IHPartsAmerica.com/tool-talk/1570-mityvac-thread.html

If that type power valve "leaks" gasoline, then you will never be able to actually set the idle mixtures, raw fuel is being dumped before the idle circuits are in play.

Did you verify that the accelerator pump check valve is in proper position and that the circuit is clean and functional? If that small valve is not in position, then gasoline will continuously emerge from the shooter and drool down into the venturis.

"average" fuel milage on a Scout II should be 12mpg +/- 2.

As scoutboy has stated, there are many threads in this sub-forum just regarding the service process for a Holley 2300, I'd spend some time looking through each thread so you can see what we're talking about here:

http://www.forums.IHPartsAmerica.com/carb-tech/1780-2300-rebuild-1966-Travelall.html
 
I have read thru most of the 2300 infor, I will go back and reread from 45 on.

Yes im using the odometer, and I know its not accurate. I have larger tires. But 7.3 mpg is way to low, even if im off some. 107 miles on a tank of fuel (19 gal) is no good.

Michael, I should have done more research before the rebuild but I didnt so.... Do you think I should start over? I am going to tear it back down and confirm the power valve is or isnt working, I do have the right gasket for small holed pv. I did check the gap on the accelarator check ball, but I dont remember throughly checking the circuit for function. I have looked and didnt see any fuel dribbling from the shooter not that it isint leaking. Is my pv theory not possible. Is it possible to have the rig idle reasonably smooth with a bad pv? I do have a mityvac so I can run the tests. Guess ill know after that. If I can figure out how to post pic ill take some during the tear down. Is there anything else im overlooking with ignition that could cause such a Rich condition? Thanks again.
 
fireride said:
Yes im using the odometer, and I know its not accurate. I have larger tires. But 7.3 mpg is way to low, even if im off some. 107 miles on a tank of fuel (19 gal) is no good.
Click to expand...

Big tires and no re gearing will/can kill mileage. Add 25% for odometer error and 10-15% for lugging the engine down so it needs to run in power more more often. You are close say 10-11mpg+. About what you should expect.

To a point getting the rpm into a sweet spot (250-300rpm below peak torque) will allow the engine to produce cruise power levels and not need high throttle angles and manifold pressures that make the power valve kick in.
 
I get what you saying. But I dont think its what I have going on here. 3.73 with 33s isnt that bad and im showing lots of signs of an overly Rich condition. Black soot tail pipe, heavy decel rumble in the exahaust. I dont trust the rebuild kit and job I did the first time. Im ordering up the holly kit and brass float. Ill post up pictures of the current gaskets and pv. And let u guys see what im dealing with. If I still have crappy mileage after the next rebuild at least I can be confident its not the carb and just all the variables of large tires speedo off etc. Or something else.

I dont remember if I mentioned or not but im not heavy footed at all. Im very cautious of the way I drive in regards to mpg.
 
Update, I pulled the carb apart. It looks like the gaskets are alright. My list number is 2463-1. Hopefully my pictures will attach.

This is the carb with the current gaskets from the car quest kit and one of the metering gasket from Holley. I traced all the passage ways. The gaskets I was using seem to all be ok. The new gaskets all seem to be ok as well. The only question is the pic with the pointer showing a passage that does not have a hole. However the carb body has no hole either. I assume its ok.

When I removed the carb before I disasembled I used the mityvac and tried to pull a vacum through the pv vacum passage. It would not hold. Am I not testing that circuit correctly. I used a cone shaped attachment inserted in the pv passageway in the base of the carb. If I am correct I had a leak somewhere and the pv was not functioning correctly. I did confirm the pv was good onced removed. Am I on the right track?

I also made sure the accelerator pump ball was free and sealing correctly. I will re gap before I reassamble.

Last pic shows the accelerator pump screw holes. Two are stripped out. Should I helicoil or jb weld and tap. Worried about having enough material to driil out and put a helli coil inn.
 

Attachments

  • CIMG1869 (800x600).jpg
    CIMG1869 (800x600).jpg
    138.2 KB · Views: 617
  • CIMG1870 (800x600).jpg
    CIMG1870 (800x600).jpg
    133.6 KB · Views: 591
  • CIMG1871 (800x600).jpg
    CIMG1871 (800x600).jpg
    161.2 KB · Views: 585
  • CIMG1872 (800x600).jpg
    CIMG1872 (800x600).jpg
    146.9 KB · Views: 596
  • CIMG1873 (800x600).jpg
    CIMG1873 (800x600).jpg
    175.2 KB · Views: 584
  • CIMG1874 (800x600).jpg
    CIMG1874 (800x600).jpg
    142.6 KB · Views: 585
  • CIMG1875 (800x600).jpg
    CIMG1875 (800x600).jpg
    149.5 KB · Views: 604
  • CIMG1876 (800x600).jpg
    CIMG1876 (800x600).jpg
    164.2 KB · Views: 289
  • CIMG1877 (800x600).jpg
    CIMG1877 (800x600).jpg
    162.4 KB · Views: 592
Thanks for the picture post. Im planning on reassembling tomorrow. If anyone sees something ive missed or should be concerned with I would appreciate the input.

Thanks scott
 
fireride said:
update, I pulled the carb apart. It looks like the gaskets are alright. My list number is 2463-1. Hopefully my pictures will attach.

This is the carb with the current gaskets from the car quest kit and one of the metering gasket from Holley. I traced all the passage ways. The gaskets I was using seem to all be ok. The new gaskets all seem to be ok as well. The only question is the pic with the pointer showing a passage that does not have a hole. However the carb body has no hole either. I assume its ok.

When I removed the carb before I disasembled I used the mityvac and tried to pull a vacum through the pv vacum passage. It would not hold. Am I not testing that circuit correctly. I used a cone shaped attachment inserted in the pv passageway in the base of the carb. If I am correct I had a leak somewhere and the pv was not functioning correctly. I did confirm the pv was good onced removed. Am I on the right track?

I also made sure the accelerator pump ball was free and sealing correctly. I will re gap before I reassamble.

Last pic shows the accelerator pump screw holes. Two are stripped out. Should I helicoil or jb weld and tap. Worried about having enough material to driil out and put a helli coil inn.
Click to expand...

Another reason for not using these type carburetor kits on the Holley modular carb. There are thousands of variations of the 2300, and there were hundreds of kits offered for the exact list number over time. Today the actual variations have been combined into only a few numbers and none of 'em are exactly correct for any one particular carb unless very close attention is paid to gasket hole positions, etc.

Looks to me like some of your holes don't match worth crap!

When you test the power valve it must be removed or mounted only in the metering body. When vacuum is applied, the power valve will close and stay firmly closed as long as a vacuum signal is present (minimum of about 10"hg). Once re-installed, it's actual operation would be tested also and again, it must hold a constant vacuum when "closed".

All damaged threaded holes are always repaired with helicoil or drilled/tapped to the next oversize. Jbweld has no business being used on a carburetor except externally to aid in sealing a plugged hole.
 
Thanks for the help. Carb is back on and it runs great. Idle is super smooth, tip in instant, decel back fire gone. I think I had a combination of problems going on. The kit I used originally sucked. The throttle plate to throttle body was not tight enough. Accel pump ball gap was to big. The screws for the accel pump base were stripped and lose. But, this is how we learn, by mistakes. Looking foward to checking the mpg this week. You guys rock. Thanks again.
 
Good deal. Lets git the pool started. I gotta dollar here. Go ahead and put me down for double your previous mpg figure.:icon_mrgreen:
 
You must log in or register to reply here.
Back
Top