Milwaukee Midget

[fordboy628]

Also: took some manifold measurements from the cylinder head.   Going to try to come up with a better head/manifold match.
Inlet port @ head face, 37mm dia.,  134.5mm C/C spacing.
Steel manifold @ head face, 34mm dia.
Aluminum manifold @ head face, 32mm dia.    There are some issues @ the carb face on both manifolds as well.

Custom match ported intake an option? I wouldn't think it would be too hard to get some flanges made, and tubing cut....  

Probably.   Although the plan is to thoroughly flog the existing parts first.    Since the aluminum manifold had 1.4" of vacuum @ WOT above 7600 rpm, there appears to be room for improvement both in the carb & the intake manifold.   On the 100+ bhp/litre BMC stuff I've done before, the inlet manifolds were larger volume & cross section, AND the carb choke diameter was larger.   As was the engine displacement.    You can always go bigger.   It's tough to get smaller without lots of extra parts.
 
Fordboy

[Jack Gifford]

... Lash settings are determined by:
1/  Height of the clearance ramp ground into the cam blank...

Finally- a breath of fresh (knowledgeable) air in here...

[Milwaukee Midget]

... Lash settings are determined by:
1/  Height of the clearance ramp ground into the cam blank...

Finally- a breath of fresh (knowledgable) air in here...

It ain't always about beer!

Jack, did you pull the trigger on that Dodge in Illinois?

[fordboy628]

Midget,

Want to put together a list of things you wish to validate on the dyno 5/28.   Want to total the number of possible dyno pulls to make certain we finish up within a reasonable amount of time.   Can use the old dyno checklist and the list of pulls from the previous dyno session as a starting point.   Like J. "Hannibal" Smith, "I want to have a plan" . . . . . .
 
Fordboy

[Milwaukee Midget]

1. Re-adjust the #2 Intake valve - .022 – that was the valve we replaced after last September.

2. Change out the oil filter and top off the oil.  Can you bring your filter cutter?  I want to make sure we're not creating shards.

3. Start with the shorty header and dial in the DCOE.
 
4. After we’ve got it dialed in, I’ll want to reinstall the air filters and make sure they’re not choking off air.

5. Check the LCB header and either eliminate it or proceed with it.

6. Check the short intake manifold and either eliminate it or proceed with it.

7. I hope to log Air/Fuel data to the point where we can put together a chart that we can use to have some direction as to how to adjust jetting on the salt, if necessary.  The Midget does have an A/F ratio meter.
 
8. Time permitting, I’d like to experiment with trimming the timing on the 2 and 3 cylinders, which I think are the ones more prone to detonation.  We might be able to increase the advance on 1 and 4, and still not grenade the thing, IF advance is what the engine is asking for. 

[Graham in Aus]

Rebuilding/modifying your 45DCOE & the 48DCO I've loaned you.

Found the problem with the 45's accelerator pump circuit, you took a silver (solder) bullet in the foot . . . . .  you need some practice with that shootin' (soldering) iron. . . .
Will post pics later for a Weber on-line build diary tutorial . . . . . .    These changes should solve the problem with the 45DCOE carb.
 

  I recall a looooong time ago talking to Chris about blocking this off to increase pump shot volume, I guess the hole was not blocked off?

Or did I add to your woes!  

Look forward to a Weber tutorial Kemo Sabe-Boy style  

[Milwaukee Midget]

Rebuilding/modifying your 45DCOE & the 48DCO I've loaned you.

Found the problem with the 45's accelerator pump circuit, you took a silver (solder) bullet in the foot . . . . .  you need some practice with that shootin' (soldering) iron. . . .
Will post pics later for a Weber on-line build diary tutorial . . . . . .    These changes should solve the problem with the 45DCOE carb.
 

  I recall a looooong time ago talking to Chris about blocking this off to increase pump shot volume, I guess the hole was not blocked off?

Or did I add to your woes!  

Look forward to a Weber tutorial Kemo Sabe-Boy style  

Graham, it's really quite simple -

I soldered up the wrong hole.

Fordboy - you have the parts - if you can find the time, can you shoot a pic of which hole I filled, and which one I was SUPPOSED to solder up?

As always, I want to document the goof-ups AND the successes. 

And sometimes, the prefix of SUCCESS is SUCKS . . . 

[Milwaukee Midget]

Lords and Ladies – a communiqué of great import from the upper lowlands –

The Wizard of the Lake has found additional flow in the vortices and chambers of the Weber of Woe – flow once forbidden entry into the fiery chambers of Abingdon on Thames.

Consultation over Ale and Mutton will proceed Sunday hence.
     
By order of the Monarch of Midgetdom, all flow has been ordered released, and the increase of the equine stable count has been ordered retabulated no later than Tuesday.

[fordboy628]

Rebuilding/modifying your 45DCOE & the 48DCO I've loaned you.

Found the problem with the 45's accelerator pump circuit, you took a silver (solder) bullet in the foot . . . . .  you need some practice with that shootin' (soldering) iron. . . .
Will post pics later for a Weber on-line build diary tutorial . . . . . .    These changes should solve the problem with the 45DCOE carb.
 

  I recall a looooong time ago talking to Chris about blocking this off to increase pump shot volume, I guess the hole was not blocked off?

Or did I add to your woes!  

Look forward to a Weber tutorial Kemo Sabe-Boy style  

Graham, it's really quite simple -

I soldered up the wrong hole.

Fordboy - you have the parts - if you can find the time, can you shoot a pic of which hole I filled, and which one I was SUPPOSED to solder up?

As always, I want to document the goof-ups AND the successes. 

And sometimes, the prefix of SUCCESS is SUCKS . . . 

How to Modify your Weber Carburetor properly  OR

Weber Carburetor Porn!!!!  OR

How to turn your expensive Italian/Spanish engine bit into an undriveable piece of crap . . . .   Part one . . . .   (yes, this will be a multi-step tutorial . . . .)

Midget, et all,

Although these modifications will be specifically for Weber Carbs, the concepts behind the ideas will work for most throttle shaft carburetors that utilize fixed venturies ("chokes")and fixed boosters ("aux venturies").

I shouldn't have to say this, BUT, if your carb is not clean and in PERFECT working order, deal with that beforehand.   Buy a rebuild/tuning manual SPECIFICALLY for your carb, as I am not going to cover basic rebuilding/installation/synchronization/vacuum leaks/linkage.   LOTS of time is wasted trying to tune Weber carbs that need to be rebuilt.   DO NOT waste your time on an old, used Weber!   Just clean and rebuild it first.    Replace any/all worn and/or questionable parts.    If you can't tell if the part needs to be replaced, you should not be rebuilding the carb!    Take/send the carb to a Weber specialist, it's cheaper in the long run.

Before starting, a disclaimer:
Carb modification, especially Weber carb modification, should not be undertaken lightly.   Weber parts are expensive, often difficult to obtain, AND, easily turned into junk by the enthusiastic, unwary, would be tuner.   The best method is to amass a large pile of GENUINE Weber parts to start with, AND, have access to a flow bench LARGE ENOUGH TO FLOW CARBURETORS, to verify your work/"improvements".    Caveat emptor.

The accelerator circuit.


This circuit consists of:
1/   accelerator pump piston/rod assembly          tuneable via: pump stroke length, spring force, actuator arm to throttle shaft position
2/   accelerator pump inlet/bleedback valve         tuneable via: variable diameter of "bleedback" orifice (hole size)
3/   pump discharge check valve(s)                     not normally tuneable, but the brass weight can be shortened/substituted, etc.  I recommend you DO NOT mess with this.
4/   accelerator pump discharge jets                   tuneable via: jet orifice (hole size)

How it all works:
1/   accelerator pump piston/rod assembly.    The length of the pump stroke determines the volume of the potential pump discharge.   The spring force determines the rate of the potential pump discharge.    The actuator arm to throttle shaft position determines the timing of the pump discharge to throttle blade position.   These are inter-related.   The vast majority of the time, there is no need to change any of these variables.

2/   accelerator pump inlet/bleedback valve.   This oneway valve allows the accelerator pump well to fill, AND, the size of the "bleedback" orifice (hole) diminishes the pump volume.   This is a REVERSE relationship!   Thus, the BIGGER the hole, the LESS volume is pumped out!

3/   pump discharge check valve(s).     These balls and weights keep the carb from discharging fuel from the discharge jets when ever there is adequate depression through the carb venturi.    There is no normal need to change this relationship.

4/   accelerator pump discharge jets.    The size of the orifice (hole) in these jets affects how much fuel is discharged, AND, how quickly.   Standard relationship, thus, the larger jet discharges more fuel, more quickly than a smaller jet.

The majority of the time, effective tuning can be managed via changing the pump dischage jets and/or the "bleedback" valve.

Ahem, so to the point.    One of the tuning "tips" for Weber carbs circulating about various racing venues is how you can increase the accelerator pump "shot" by soldering up the "bleedback" hole/valve.    While this does increase the "pump shot" if done properly, it is also difficult to "undo", in the event that it does not solve your problem.   These jets are available from Weber in .05mm increments from approximately .35mm to 1.00mm if my memory serves me correctly.   THERE IS ALSO, UNSURPRISINGLY, A .00 WITH NO "BLEEDBACK" HOLE.    Photos below:


           various sizes of "bleedback" valves  00 to 100                                          "inlet" end of the same valves

You will notice that one of the valves has been filled with electrical solder, probably in an attempt to "keep the smoke inside". . . . . . . . . . .

As a public service, IF, you are ever in desperate need of more "pump shot" on your Weber, and you can not beg, borrow or steal a proper jet, the hole to solder up is the "bleedback" hole on the side of the jet, NOT THE INLET HOLE ON THE BOTTOM OF THE JET.   (Very bad, doesn't help anything, makes carb much worse. . . .)  I suppose you could solder it up and redrill a smaller opening with a Weber jet drill set, but I just change the parts, less confusing in the long run.

OK, that's all for now.   I have a load of pics & flowbench numbers for the carb mods I did to MM's "Vergaser".    Stay tuned.
 
Fordboy

[Milwaukee Midget]

[/URL]
           various sizes of "bleedback" valves  00 to 100                                          "inlet" end of the same valves

You will notice that one of the valves has been filled with electrical solder, probably in an attempt to "keep the smoke inside". . . . . . . . . . .

As a public service, IF, you are ever in desperate need of more "pump shot" on your Weber, and you can not beg, borrow or steal a proper jet, the hole to solder up is the "bleedback" hole on the side of the jet, NOT THE INLET HOLE ON THE BOTTOM OF THE JET.   (Very bad, doesn't help anything, makes carb much worse. . . .)  I suppose you could solder it up and redrill a smaller opening with a Weber jet drill set, but I just change the parts, less confusing in the long run.

From the movie, "Casablanca" . . .

Renault: And what in heaven's name brought you to Casablanca?
Rick: My health. I came to Casablanca for the waters.
Renault: The waters? What waters? We're in the desert.
Rick: I was misinformed. 

[fordboy628]

[/URL]
           various sizes of "bleedback" valves  00 to 100                                          "inlet" end of the same valves

You will notice that one of the valves has been filled with electrical solder, probably in an attempt to "keep the smoke inside". . . . . . . . . . .

As a public service, IF, you are ever in desperate need of more "pump shot" on your Weber, and you can not beg, borrow or steal a proper jet, the hole to solder up is the "bleedback" hole on the side of the jet, NOT THE INLET HOLE ON THE BOTTOM OF THE JET.   (Very bad, doesn't help anything, makes carb much worse. . . .)  I suppose you could solder it up and redrill a smaller opening with a Weber jet drill set, but I just change the parts, less confusing in the long run.

From the movie, "Casablanca" . . .

Renault: And what in heaven's name brought you to Casablanca?
Rick: My health. I came to Casablanca for the waters.
Renault: The waters? What waters? We're in the desert.
Rick: I was misinformed. 

This is why factory exploded parts diagrams, full color schematics of circuit functioning, factory parts and service manuals help quite a bit in explaining the functioning of a complicated assembly like a Weber carb . . . . . .

Proper modifications?    Why yes, thank you.   May I have seconds?

Dicking about?    NO, Thank you.      Uhmmm, say . . . . did you used to be Pam Anderson?
 
Fordboy

[38flattie]

Now where have I seen thast plugged jet before? Lol!

Luckily, you guys detected this after the dyno run, and not after you had made a trip to the salt!

Go get 'em, guys!

[Milwaukee Midget]

That would have been right here -

After confirming the part, I removed the “carby” and soldered up the jet. 

I was in consultation at the time, but I can't blame anybody but myself.  The advice given was correct - the execution was the problem.

Operator error . . .

The funny part is, 2 weeks later, I clicked of a 93 at Maxton in third gear - with what I now realize was NO ACCERATOR PUMP.  I thought it was just slow coming up on the cam . . . 

Kind of like me, at times . . .

[fordboy628]

How to Modify your Weber Carburetor properly  OR

Weber Carburetor Porn!!!!  OR

How to turn your expensive Italian/Spanish engine bit into an undriveable piece of crap . . . .   Part two . . . .  (yes, this will be a multi-step tutorial . . . .)

Midget, et all,

Although these modifications will be specifically for Weber Carbs, the concepts behind the ideas will work for most throttle shaft carburetors that utilize fixed venturies ("chokes")and fixed boosters ("aux venturies").

I shouldn't have to say this, BUT, if your carb is not clean and in PERFECT working order, deal with that beforehand.   Buy a rebuild/tuning manual SPECIFICALLY for your carb, as I am not going to cover basic rebuilding/installation/synchronization/vacuum leaks/linkage.   LOTS of time is wasted trying to tune Weber carbs that need to be rebuilt.   DO NOT waste your time on an old, used Weber!   Just clean and rebuild it first.    Replace any/all worn and/or questionable parts.    If you can't tell if the part needs to be replaced, you should not be rebuilding the carb!    Take/send the carb to a Weber specialist, it's cheaper in the long run.

Before starting, a disclaimer:
Carb modification, especially Weber carb modification, should not be undertaken lightly.   Weber parts are expensive, often difficult to obtain, AND, easily turned into junk by the enthusiastic, unwary, would be tuner.   The best method is to amass a large pile of GENUINE Weber parts to start with, AND, have access to a flow bench LARGE ENOUGH TO FLOW CARBURETORS, to verify your work/"improvements".    Caveat emptor.

The throttle shaft and blade adjustments.

A little known fact about most (yes, even new) Webers is that the throttle shaft and blades usually are overcentered at WOT.    This is the first adjustment to be made as the throttle shaft stop is usually the idle speed screw stop . . . .               See photos below of MM's virtually new 45DCOE.

        Throttle stop as delivered, about 8 degrees over center.                        Throttle stop adjusted for 90 degree opening.

This condition normally costs you between 2 to 4 cfm @ the carb, @ 28" test pressure, depending on angular degrees, carb size, choke size, etc.   This is the equivalent of giving away .75% to 2% of the flow available through the carb!!

There may be a situation where the carb/manifold combo flows better with the carb opened more than 90 degrees.   I have yet to encounter this situation in all of the testing I have done.    I have encountered, however, some manifold/carb combos which flow better with the carb opening slightly less than 90 degrees.    If your carb intersects your manifold @ a steep angle, you MAY want to experiment with this on the flow bench to find the best results.    I theorize that a slight angle on the carb blades helps the air make the turn more efficiently.    I have never tested this with "wet" flow, and fuel being heavier than air, may not respond as well with the angled carb blades.    CAVEAT EMPTOR.     Anybody out there who has done this type of flow work, feel free to post in.

It pays off to pay attention to ALL the details . . . . . . . .
 
Fordboy

[Milwaukee Midget]

How to Modify your Weber Carburetor properly  OR

Weber Carburetor Porn!!!!  OR

How to turn your expensive Italian/Spanish engine bit into an undriveable piece of crap . . . .   Part two . . . .   (yes, this will be a multi-step tutorial . . . . )

Thanks for dividing up the beatings into bite-sized chunks.