Idle mixture screws have no affect on synchometer calibration

[Ggmac]

Re: Idle mixture screws have no affect on unisink test

Switch carbs front to rear rear to front , recheck . This will not help but could possibly eliminate a leak at other than the carb butterflies or shafts . I once had a TR-6 that I just installed a manifold and Webers on . No matter what I did I could not sync carbs . Working at jaguar at the time so it was done every day . Narrowed it down to a casting flaw causing some kind of unequal airflow .
Even if you send your carbs out , chances are your going to need to get the basics down on synchronized carb set up procedures.
A carb butterfly could be bent , hole drilled in it for hi , very hi lift camshaft , or a few other possibilities. If you remove your sucking carb and make a rubber adapter to attach to each barrels base and attach a vacuum cleaner while having a small hose on its top side listening for air flow , now do the other barrel , it should sound the same . Adjust the idle screws shut while doing this or before . Make sure your choke linkage isn't holding it on hi idle .
If your up to it now do the other carb , each barrel by itself and compare the sucking sound to each other .
Just a suggestion, much easier for me to show than trying to explain .

 

[flatjack9]

Re: Idle mixture screws have no affect on unisink test

I tune my cars initially by listening at the mouth of each carb with a length of hose. You can get pretty darn close by adjusting to get the same sound. Then to fine tune, use the meter.

 

[scicala]

Re: Idle mixture screws have no affect on unisink test

I had it happen, that is why I mentioned it. It was not on a flathead, its was on a '56 324 Olds I have in a Model A Pickup. It has a two-carb Edmunds intake on it. The carbs were on it when I got the car. They are 4-bolt Stromberg "Aerotype" two barrel carburetors. I have never figured out exactly what they are off of? Somebody told me they were Buick straight eight carbs but I don't know that for sure. Nothing showed up searching the carb number. No carb kits, nothing.

I had the linkage disconnected and no return springs on the carbs. I started it with a remote starter switch and those throttles flew right open. It took me only a split second to get to the ignition switch but that engine was already way past its redline and in Nascar territory.

The Stromberg 97 carbs seem to have the throttle shaft pretty much in the center of the bore. Anyway, a lot closer to center than others. If the Stromberg two barrels you used were made the same, I could picture the throttle opening by itself.


The Holley 94's and all others I can think of are offset from center.


Anyway, that must have been a scary moment with your car !


Sal

 

[RandyMettler]

Re: Idle mixture screws have no affect on unisink test

With all your advice, the process is logical now. The problem with only one carb sucking and ******* my snail synchometer at 30 kg/h easily swiched to the other 94 when taking off the linkage and adjusting the rpm screws. This indicates that the carb is not the problem, it was my previous adjustment procedures. I was using the linkage to adjust the throttle plates.

I know my throttle plates have the ability to fully close and seal because I have had the 94s apart a few times and replaced the accelerator plunger, gaskets, power valves, jets, etc. The throttle shafts appear to be tight.

I have since been able to sync the carbs both at 18kg/h. Anything lower and the car wants to stall. I ran out of gas so I will fine tune tomorrow. The car does like its gas. It goes through a gallon of gas in about 15 minutes of idling, even with my new fuel pressure regulator set to 3 pounds.

My new Charlie NY fuel pump did stop the fuel to oil contamination. Thanks to Charlie!

If you read the"My dipstick is lying to me", I have since scored my dipstick at the 4 quarts full level. Again, thanks to all the senior members that helped me out.


And thanks Flathead Fever to for the heads up for the need for throttle plate tension during the syc process!

Its good to be fixing all the annoying problems. I am looking forward to getting the thing out on the road.

 

[scicala]

Re: Idle mixture screws have no affect on unisink test

Great to hear !


Sal

 

[scicala]

Re: Idle mixture screws have no affect on unisink test

"They are 4-bolt Stromberg "Aerotype" two barrel carburetors. I have never figured out exactly what they are off of? Somebody told me they were Buick straight eight carbs but I don't know that for sure. Nothing showed up searching the carb number. No carb kits, nothing."


Buick used a Stromberg two barrel from the late 30's through about 1955 (model AAV). In '56 it was replaced by the Stromberg WW two barrel. I believe other makes of cars used the AAV carb too.


Sal

 

[RandyMettler]

Re: Idle mixture screws have no affect on unisink test

With all your advice, the process is logical now. The problem with only one carb sucking and ******* my snail synchometer at 30 kg/h easily swiched to the other 94 when taking off the linkage and adjusting the rpm screws. This indicates that the carb is not the problem, it was my previous adjustment procedures. I was using the linkage to adjust the throttle plates.

I know my throttle plates have the ability to fully close and seal because I have had the 94s apart a few times and replaced the accelerator plunger, gaskets, power valves, jets, etc. The throttle shafts appear to be tight. I have since been able to sync the carbs both at 18kg/h. Anything lower and the car wants to stall. I ran out of gas so I will fine tune tomorrow. The car does like its gas. It goes through a gallon of gas in about 15 minutes of idling, even with my new fuel pressure regulator set to 3 pounds.

My new Charlie NY fuel pump did stop the fuel to oil contamination. Thanks to Charlie!

If you read the"My dipstick is lying to me", I have since scored my dipstick at the 4 quarts full level. Again, thanks to all the senior members that helped me out.

Its good to be fixing all the annoying problems. I am looking forward to getting the thing out on the road.

 

[Bob C]

Re: Idle mixture screws have no affect on unisink test

"They are 4-bolt Stromberg "Aerotype" two barrel carburetors. I have never figured out exactly what they are off of? Somebody told me they were Buick straight eight carbs but I don't know that for sure. Nothing showed up searching the carb number. No carb kits, nothing."


Is this what they look like?

 

[Flathead Fever]

That sure looks like them. I went out and looked. It little hard to get to the car.

The poor car. The last time it was started was for the 60th Hot Rod Magazine Reunion, for cars featured in the magazine. They called me up recently for the 70th reunion and I declined. It still has the same fuel it in from the 60th reunion. I'd would have had to clean it for the show and it just starting to get that nice barn find look. I've had five back and shoulder surgeries since that 60th reunion so productivity has gone down around here.

This is a '28 Model A Roadster "Car" converted into a pickup cab. It was a '25 Model T bed on it. Built during the War it was originally red with a flathead and then repainted black and a 303 Olds installed in 1950. It now has a 324 Olds. It took second place in it class at the first 1950 Oakland Roadster show. Won the Pasadena Reliability Run. Its in a bunch of early hot rod magazines. It belonged to the guy that invested the glass pack muffler.

 

[aussie merc]

ok having read this it sounds like you have a vacum leak from another source IE wiper motor hose or even a bad intake gasket that is leaking from within the cam valley so now to track it down 1 remove and plug all vacume taps ie wiper motor etc if no change attach vacume gauge to manifold and check eng vacume take notice if steady or pulseing refer to charts for vacume gauge[ from net] them if unable to locate problem go back to basics and start again there are several good posts on setting up and tuning multi carbs on this site

 

[Tinker]

Looks like you found your air/vacuum leak. nice work, way to stick to it.

 

[cas3]

bob c, that aerotype carb was on my ww2 white halftracks too. i think the flathead caddys too