Triple OER/SK carb issues, not balancing (SOLVED)

[duffymahoney]

Could you swap 1 and 2. That will show you for sure if it’s float or needle?

[Jazz86]

2 minutes ago, duffymahoney said:

Could you swap 1 and 2. That will show you for sure if it’s float or needle?

I will do that next time. Going to take apart carb #2 as well when it's off and report my findings.

[Jazz86]

I'd like to add that my lean condition on cylinders 3 and 4 are mainly caused by the #2 carb sucking in too much air through the throat. Since the vacuum can be read on the Unisync for a split second. It reads off the scale. Meanwhile the same unisync on carbs #1 and #3 read perfectly in the middle. I also checked how far open my butterfly valves are open on all the carbs through the progression holes and they are all in the same place. 

Edited October 24, 2017 by Jazz86

[240260280]

fuel flow check:

Just hold the lid to your face and blow air through the fuel entrance in the lid.  Open and close the needle valve by moving the float and you should hear the air stop and start when the valve opens and closes.

 

Balancing:

Too much vacuum on one carb at idle means it is doing all the work and the other two are not.  You need to close the throttle valve stops on all to be the same before you start balancing.  Also ensure the idle enrichment screws are all backed out by the same amount at start.   Do not turn any enrichment screws until the air is first balanced.

 

Here are the steps to follow:

 

1. Gently turn all 6 idle enrichment screws in until they stop then back each out 1 full turn (note: some recommend anywhere between 1.5 turns to 2.5turns however the SK Carb manual recommends between 3/4 to 1 full turn so 1 full turn should do)

2. Disconnect push rods from carb arms.

3. Turn back all 3 idle stop screws until  each is not touching the idle stop.  Then turn each in until it just kisses the stop, then give each an additional 2 turns to open the throttles a crack.

4. Start the engine and let it warm up for 10 min until it is nice and hot. (Don't worry about rpms unless they are too low).

5. Measure the air flow into each carb and adjust the idle stop screws until you get the air balanced AND such that you have lowered the rpms to between 650 and 850rpms.

Hopefully this will get you in the ball park before you have to mess with the enrichment screws and linkage.

 

 

Edited October 24, 2017 by 240260280

[Travel'n Man]

First dump the unisync. It does nothing but choke down the carbs. Spend the money and get a syncrometer. No choke down at all. Second what is you fuel pressure feeding your fuel? Third. Not only is your temp warm but bring your oil temp to a min of 180 before you turn your carbs. Last what is your AFR at once warmed at idle? You can always move carb #2 to either the first or third position and see if the problem moves with you. All in my opinion of course


Sent from my iPhone using Classic Zcar Club mobile

[Jazz86]

5 hours ago, 240260280 said:

fuel flow check:

Just hold the lid to your face and blow air through the fuel entrance in the lid.  Open and close the needle valve by moving the float and you should hear the air stop and start when the valve opens and closes.

 

Balancing:

Too much vacuum on one carb at idle means it is doing all the work and the other two are not.  You need to close the throttle valve stops on all to be the same before you start balancing.  Also ensure the idle enrichment screws are all backed out by the same amount at start.   Do not turn any enrichment screws until the air is first balanced.

 

Here are the steps to follow:

 

1. Gently turn all 6 idle enrichment screws in until they stop then back each out 1 full turn (note: some recommend anywhere between 1.5 turns to 2.5turns however the SK Carb manual recommends between 3/4 to 1 full turn so 1 full turn should do)

2. Disconnect push rods from carb arms.

3. Turn back all 3 idle stop screws until  each is not touching the idle stop.  Then turn each in until it just kisses the stop, then give each an additional 2 turns to open the throttles a crack.

4. Start the engine and let it warm up for 10 min until it is nice and hot. (Don't worry about rpms unless they are too low).

5. Measure the air flow into each carb and adjust the idle stop screws until you get the air balanced AND such that you have lowered the rpms to between 650 and 850rpms.

Hopefully this will get you in the ball park before you have to mess with the enrichment screws and linkage.

 

 

Thanks, I have already tried the mikuni and weber baseline settings as I am no stranger to triple webers but this problem is something that confuses me and my fellow triple carb friends.

[Jazz86]

24 minutes ago, Travel'n Man said:

First dump the unisync. It does nothing but choke down the carbs. Spend the money and get a syncrometer. No choke down at all. Second what is you fuel pressure feeding your fuel? Third. Not only is your temp warm but bring your oil temp to a min of 180 before you turn your carbs. Last what is your AFR at once warmed at idle? You can always move carb #2 to either the first or third position and see if the problem moves with you. All in my opinion of course


Sent from my iPhone using Classic Zcar Club mobile

Fuel pressure is at a stock 3.5-4psi since I am running the stock mechanical pump and an electrical primer pump. And yes, the car is all warmed before I tried to tune it, it's common knowledge. As for afr, there is no way to get an O2 sensor on all exhaust runners, I can only tell via spark plug (rich or lean). And yes I couldn't agree more, moving it will help me tell if its the carb alone.

[240260280]

Maybe the throttle rod in carb #2 is twisted.

Did you look in progression holes to see where throttle plates come to rest in the throat with the stop screws back off all the way? Compare all 6.

Carb two is not closing enough.

Edited October 25, 2017 by 240260280

[Jazz86]

Just now, 240260280 said:

Maybe the throttle rod in carb #2 is twisted.

Did you look in progression holes to see where throttle plates come to rest in the throat with the stop screws back off all the way?

Yup, That was one of the things I looked into. The progression holes are #2 carb exactly the same as #1 and #3. However, that is with #1 and #3 turned about 1 turn, and they are synced perfectly. The #2 carb with the screw just making contact the progression holes match the #1 and #3

So the butterfly valves are all in the same place in relation to the progression holes; just barely exposing the edge of the first hole. 

CARB 1 :1 turn      progression holes exposed the same amount but different turns

CARB 2 :0 turns

CARB 3 : 1 turn

[240260280]

OK then it is probably the rare case where the cold start circuit is not sealing on carb #2. Check it out.

[240260280]

btw the vacuum ports for tuning are not leaking or opened?

[Jazz86]

7 minutes ago, 240260280 said:

OK then it is probably the rare case where the cold start circuit is not sealing on carb #2. Check it out.

Yes, that is exaclty what one of my freinds just suggested!!! How do I go about checking that for leaks. I believe it has to do with plunger near the choke?

5 minutes ago, 240260280 said:

btw the vacuum ports for tuning are not leaking or opened?

Yes, the vacuum ports all have a rubber cap and I sprayed carb cleaner on them to double check.

Thanks again for giving my issue so much thought.