requesting advice

Have some one run a compression check...  I assume the carbs are single throat types, so "idle jets" should not be the problem....  It may be an air leak on that cylinders intake....  First things first, get the compression check...

You might want to pull the valve cover on that side and check your valve clearances....  Just a thought....

I use a set of those empi carbs myself, had a bit of trouble syncing them in the first place, it may be a mixture issue as well. I remember playing with the mixture screw on the one bank and had a similar issue to what you described.

The small dual ICT carbs you have(?) There is some discussions regarding those carbs,and some have had issues with the "short" intake manifolds not distributing the fuel well,and the taller manifolds fix this problem. Some of the dual carbs can be problematic to setup. Good luck and a simple compression test will help. Also try switching plugs and see if the dead cylinder stays or migrates with the plug change. Also check wires and connector ends. Good luck!  

Also check the intake on that side the gasket may not have sealed corectly  on #1

I have heard some people say that with dual 1 barrel carbs the motor can seem like it's only idling on 2 cylinders, and pulling 2 plug wires will make almost no difference, while with the other 2 it will be very obvious. At just above idle it again runs on all 4. I never noticed it with kadrons, but that was 30 years ago.

Yes Alb,you are correct. I have a 71 Bus with dual kadrons and the car idles smoothly however it does have that strange phenomena of idling stronger on 2 cylinders than the others,something to do with the joined/plenum manifold not keepinmg a strong enough vacuum to supply both cylinders at idle equally. It is very odd,but it "works" and runs well.

  

did you change the cylinder heads or the springs and what weight oil is on?

I had the same problem related with 30W oil. switched 50W and the problem was solved

I'm puzzled; how would a heavier weight oil change the idling characteristics of dual 1 barrel carbs?

Second that...???????

Have you checked for intake air leaks?

 

Also check the spark plugs to make sure they are dry.

 

Another quick thing you can do is swap the wires going to #1 & #2 cylinders to make sure the wires are good.

 

After all of this if the car still misfires at idle and it is a single barrel carb, do a compression check.

 

 

My car came equipped with dual Kadron/Solex carbs and it never ran right; it was running rich, was sluggish, etc. A friend of mine had problems with his too even after spending a small fortune getting them doctored by AJ Sims at Lowbugget.com. My problems as well as his went away when we both bought sets of dual Dellorto 40's. Basically plug and play and they run like a top with no tweaking.

the answer is simple; if you are using hd springs or double springs then you might need higher oil pressure to move the valves. If your problem is not related to gas or ignition it might be this. At least it is a cheap solution and worth trying. Ask me how I know : )

I'm only a hobbyist, but I've been doing this a long time; please enlighten me how heavier oil has anything to do with actuating the valve train. Please explain...

Hydraulic lifters?

I know it sounds weird but it works. Trust me

I've spent a bit over 50 years working on VW engines and such.  This is the first time I've heard anyone say that adding 50 wt oil solved a FUEL or IGNITION problem.  

 

Sounds more like a coincidence than a remedy

The 50 weight more than likely filled in a few gaps and made it run quieter ..( for a bit)

 

you misunderstood I guess, I said: ' if it is not related to a fuel or ignition problem'...

 this mostly happens when the short runner intakes are used ,and when a biger than stock cam is used, it's reversion for the #4&2 cylinders, that weakens the 1&3 cylinders at idle.go to true 2 bbl duels(idf,hpmx,decade,dellorto carbs) and it will improve th entire driving expearance & mpg too.it is well worth the $ invested to change over.(idf,hpmx,dell,40's would be good up to about 2110 cc motor bigger than that should use a 44 mm carb.(but the 40 will work on both as will the 44, but  not as good as they should.as with everything it all needs to work togeather,but not like washington dc does.

     a taller intake may help it or may not. remember you have a lot more cc's now,and that means more cc's of reversion shooting back up the intake faster than before.

So Joel,

Whats going on? Have you done anything that we've recomended or have you had time to even look at it?

coolryde-thanks for your interest. In between the holidays and work I was able to do everything suggested except go to 50 wt. oil. I bought a compression gauge and all cylinders test out at about 135 equally.The coil gives hot spark , new cap and rotor, wires are good and new plugs.Valves are set at .006. Still #1 and#2 not firing at idle only.

Last night I switched left and right carbs(new empi 34's) and guess what? #1 and#2 fire at idle and#3 and #4 don't. Runs pretty good at higher rpms. I am supposed to get a replacement carb tomorrow so I will let you know the result. Thanks eyeryone for your suggestions.

 

Joel

might just need tuning.did you use a sync to set them corectly?clean the idle jets?have good fuel filters before each carb?

Bingo idle circuit. In any carb you have a idle circuit and a main circuit. The idle or primary jet/circuit works from idle thru about 1500-2500 rpm depending on carb. Then the main jet/circuit takes over. When posting questions up here it is very importation to include as many details as possible. You had originally stated that it was only missing on 1 cylinder and not both on that side. That coupled with the fact that you not only rebuilt the engine but also replaced the carbs left both as possible issues, however since it was only noted to be missing on 1 off the 2 cylinders that the single barrel carb was controlling it seemed to be a mechanical issue and not a fuel, air, spark issue...

make sure when you install the new carb that you disconnect the linkage from one carb and set idle first by adjusting both carbs stop and mixture screws. Then hook the linkage up and adjust the linkage to the already adjusted carbs.. This is the right way to set up carbs before sinking them. When you start sinking them, it is importation to disconnect thlinkage to adjust correctly..

 

good luck

If I read your post correctly, the problem swapped sides with the carb swap....  If so, I would suspect that the pair of carbs do not have the same jet sizes....  The one with the problem probably has a smaller idle jet and cant supply enough fuel....  Just a thought...

Update on my engine build.

 

The replacement carb cured most of the idling problem-bad idle circuit on the original. I think that MarksBug's  post hit the nail on the head.

Anyhow above idle the engine runs and pulls great. I'm sure that the new cam contributes to the loopy idle.First I ran it with the stock exhaust and then I switched to the Empi premium exhaust extracter & phat boy muffler and the engine definitely breaths better. (Alittle too  loud however.) Don't forget that the new parts-cylinders,pistons, rings,cam, lifters, etc have very few hours on them so if the weather cooperates this weekend I'm going to put some miles on it after I change the breakin oil. I had to reshape the rear engine tin to clear one of the exhaust tubes a body hammer did the job and it fits. I still have to hook up the heater? tubes- will be a challenge with this exhaust and detail the engine compartment.

I definitely have Three  Fifty Sickness and I am enjoying it. I've learned alot from this project and thanks again  you guys for your advice.

 

Joel

 

 

 

 

 

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