<VV> Syncronizing Carbs

[S M]

Well, that's just it, Mark. The linkages have slack in them, even straight from the factory, and with my (and many others') method it becomes insignificant. I'm sure Smitty's talking about my post, and while I have the greatest respect for his experience, I must disagree with him on this. I set the balance at idle with the idle speed screws, with the linkage slack and the throttle plates resting against the screws. That doesn't get messed up when you adjust the linkage on the left carb (a bit) to make up for the slack when the linkage has pressure on it. When you let up on the throttle, the levers still rest on the the idle screws. If you don't syncronize at 2000rpm the car may surge at part throttle. Maybe, maybe not if your linkage is pretty good. With very worn linkage this can be quite significant. The new style linkages are nice, but not really necessary if you do the 2000rpm adfjustment. I always double check synch at idle and it doesn't change. 
I also set valves cold and prefer Earlies... 

yea, Vairily ... Shaun 


----- Original Message -----

From: "MarK Durham via VirtualVairs" <virtualvairs at corvair.org> 
To: "Smitty" <vairologist at cox.net> 
Cc: virtualvairs at corvair.org 
Sent: Thursday, July 30, 2015 10:56:12 AM 
Subject: Re: <VV> Syncronizing Carbs 

Hmmm, there is a method to the madness. There is no reason to even verify 
sync above idle because if synced at idle it should stay synced above idle. 
Unless the linkage is worn out. 
This is why I bought Roger Parents linkage, to keep things in sync. 
Mark Durham 
Hauser, Idaho 
On Jul 30, 2015 9:49 AM, "Smitty via VirtualVairs" <virtualvairs at corvair.org> 
wrote: 

> Smitty Says; I read a post the other day and immediately started to write 
> a response that could be considered abrasive. Then I thought , why 
> bother. Well the bother to me is that if a newbie, or other, that is just 
> starting to grasp the subject, reads it, and believes it then I have done 
> him a disservice by not correcting the information. The subject was 
> synchronizing carbs and making adjustments at 2000 rpm. 
> Nowhere in any GM manual is mention made of adjusting carbs at 2000 rpm. 
> All references are to making adjustments at idle. Synchronization is for 
> the purpose of obtaining a smooth idle and no other reason. Smooth idle is 
> important from a mechanical point of view because you need a strong stable 
> idle to carry the load of dropping the PowerGlide into low gear when the 
> car is stopped. Oh, it’s nice to have a smooth idle with a stick shift 
> too, but with a PG it is a necessity. The rpms for a PG are 700 in neutral 
> and 500 in gear. You can not properly adjust idle air mixture above right 
> at 700 rpm because at that speed the throttle plate is leaving the idle air 
> slot inside the carb throat, leaving the idle circuit inoperative. All 
> the tweaking of the idle air valve in the world will do nothing for your 
> engine at speeds above 700. Of course the idle speed screws were matched 
> when you do the initial synchronization at idle. At 700 they are no linger 
> touching the speed advance cam and screwing with them will only mess up the 
> matched idle speed you have already done. now there is only one other 
> thing that is adjustable. That is the linkage. if you are following the 
> book you have the two carbs disconnected and isolated from one another. 
> Hopefully held in the idle position with rubber bands or springs or 
> whatever. You hook up the right carb first. Then you adjust the little 
> swivel on the left carb link between the cross shaft and the carb to where 
> you can just slip the swivel into the hole in the carb link. Add one 
> additional turn tighter to make the right carb crack open first to start 
> the vacuum advance. Now if the engine is turning at 2000 rpm and you screw 
> with that linkage you will destroy that fine adjustment you made at idle 
> I watched a supposedly guru at a national convention doing a tech session 
> one time. He jumped through all the wickets to synchronize the carbs on 
> the demo engine and then with a vacuum gage he matched the carbs at 2000 
> rpm. I walked away in disgust. 
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