Home › Forums › MGTD Kit Cars › VW Based Kits › Carb syncronizers
- This topic has 7 replies, 3 voices, and was last updated 13 years, 7 months ago by Bill Gayler.
July 28, 2009 at 5:02 pm #232687
I have repair kits and 2 gals. of cleaner that I plan to use to rebuild the two Weber 1bbls. on my Fiberfab Migi. All articles I’ve read says you MUST use Carb syncronizer tools. One tool looks like it has a clear tube with a ball inside at the top, while the other one looks similar to a boat compass. Is one better/more accurate/preferred over the other? Also where is the best place to purchase one.
Thanks,July 31, 2009 at 6:57 am #239330
Come on Guys! I’m dealing with a large group of VW specialist here and no one wants to volunteer the answer. I used a carb stick on my 4 cyl Honda Magna and it was fairly simple. Connect a vaccuum tube to each carb and reach the highest level of mercury in each of the 4 tubes. I’m sure dual carb VW’s sre similar, I just wanr some input on which one seems to work the best. Price isn’t that much difference but the styles appear very different and I’d like the best “Bang” for the buck.
Your opinion is very appreciated.July 31, 2009 at 9:21 am #239331Paul MossbergKeymaster
I’ve seen lovers and haters of both Unisync (clear tube with the floating red ball) and Snychrometer (the one looking like a boat compass). Here’s one comment, from a member of http://www.speedsterowners.com: “….the unisyn s–ks! Spend a couple extra bucks and get a synchrometer: http://www2.cip1.com/ProductDetails.asp?ProductCode=ACC-C10- 7125 They’re much easier to read and you can adjust the airflow by rotating the sleeve. You won’t have any choking issues.”
Here is a detailed description of the carb synch process, also “borrowed” from the guys at http://www.speedsterowners.com , and also from someone who uses the synchrometer.
Thanks to Simon Hambley and Team Evil for help with this article.
Gordon Nichols (nichols1) posted 6/16/2004 7:57:27 PM
I use a Unisyn to synchronize carbs – its the same as a Synchrometer, but looks a bit different. The Synchrometer may have an adjustment method to “baseline” it as does a Unisyn. Basically, there is something you turn or adjust to set the synchrometer meter or Unisyn float gauge for a “baseline” reading that you’ll then compare against.
If youre running basically a stock 1600 dual port and all thats been done to it is adding dual Kadrons, then this adjustment should be reasonably straight forward.
First, the Synchrometer. This is a device that measures air flow down through the throat of the carb. Thats all it does, but having that ability allows you to balance all four cylinders so that they’re all working the same amount. Balance is important, otherwise the
engine will run roughly, especially at idle. When you first use it, you must adjust it for a “baseline” reading. That means that you place it on a carb velocity stack, notice the reading on the Synchrometer and adjust it such that its reading about 1/4 scale (say, 3.0 ). Remove it and youre ready to start testing.
First, run around the block a few times to get the engine up to temperature, stop the engine and then remove the air cleaners. You should see a couple of little, vertical, trumpet cones sticking up on the top of each carb. Those are velocity stacks, and they guide the air into the throat of the carb. The Synchrometer should fit nicely onto one stack at a time.
Disconnect the linkage from one carb only (doesnt matter which one), then re-attach it but only finger tight.
SEVERAL WORDS OF CAUTION HERE. Were going to be working on a running engine with an exposed fan belt and several spinning things that can seriously hurt you. Take your time, and steadfastly avoid anything moving, like the fan belt. It can really hurt you. Nuf said.
Start your engine and let it idle. Disconnect that carbs linkage again (you needed it connected to get it started, right?) and it should stay idling.
Focus on the carb still attached to the linkage. Adjust the air mixture screw on that barrel only (that little Brass Screw on the side), by turning it in (clockwise) until the engine starts to slow down or stumble, then turn it back OUT 1/4 turn. Once attained, move to the
other stack and do the same for that stack. If you have only one barrel per side, then simply adjust each side in turn – in til it stumbles, then out 1/4 turn.
Once both barrels are adjusted for idle misture, note the reading on that last stack you maxd, and return to the first carb. Put the Synchrometer on the rear stack or the only stack if you have a single barrel) and note the reading. It may be higher or lower than the
other carb. If its lower, it means THAT carb is drawing less air than the other side, i.e. its idling slightly lower than the other side. Find the idle speed screw for that carb and turn it IN to increase the Synchrometer reading to match the other side. One of two things
may happen – it may begin to idle a bit smoother and/or it may increase in idle speed. If it is higher than the other sides reading, then turn the idle speed screw OUT to bring it down to match the reading from the other carb.
Note your idle speed. It should be between 800 and 1,000 RPM. ANYWHERE in that range is fine – its all in what sounds good to you. If it is too high or low, youll have to walk the idle speed up or down by turning the idle speed screw on both sides in turn, 1/8th turn
until you get them to where you want them and then re-check side-to-side to re-balance left-to-right. You now should have all four cylinders balanced AND your idle balanced as well.
Time to re-connect the linkage – I can smell the Beer Reward now! – Onward!
You can stop your engine now……
Dual carb linkages are adjustable separately on both sides with little turnbuckle ends on the linkage. All you have to do now is make sure the linkage is adjusted for the disconnected carb. Lift the linkage end up, and straighten it to line up with the hole on the throttle actuator. If it looks like itll go straight in, congratulations, you lucked out. If it looks a little high or low, youll need to loosen the locknut and spin the head either up or down to match the actuator hole such that itll go straight in. Once there, re-tighten the lock nut, attach the linkage, tighten it up and youre done.
Remove the Synchrometer, return the air cleaners, clean your tools and Synchrometer, put everything away and go have a beer, youve earned it. Better yet, take it out for a spin and go get an ice cream or something……..
Simon Hambly (shambly) posted 6/16/2004 7:15:05 AM
Felt I should correct one aspect of Gordons great response (sorry Gordon!); the Kadrons only have a single barrel in each carb, not two. (Unlike the more usually used weber IDFs )
The good news is that there only half the work to do to balance the Kadrons 🙂
The lowbugget.com site has great advice for setting up your Kadrons.
Setting up with the flowmeter is the way to go – mine were initially way off each other when I initially set them up by ear (causing popping on the overrun).
Back to Gordon: I, too, went to lowbugget.com and found it to be a rather tedious web site to navigate. The information is there, but he really makes you work to find it (or maybe Im just getting old!)
His recommended way of tuning carbs is the way I learned to do it 40 years ago – by ear, without a gauge. Adjust the air mixture screws the same way as outlined above, and then he listens to both sides for the same “sound” of the hiss past the venturiis. If youre good,
(and you do it a lot) you can get a carb tuned to a gnats ass that way and do the same for idle speed left to right, just by sound. To be honest, Balancing left-to-right with a Unisyn or Synchrometer is far better if youre not used to doing this.
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)July 31, 2009 at 12:48 pm #239332
Unlike the Honda 4 cylinder bike with 4 carbs, the VW with duals are sync’d one at a time. Therefore, I will only need 1 tool? I don’t mind the extra expense for the right tool, I just hate to buy the wrong one first. I knew with all the dual carbs out there someone had the right answer. I really appreciate it.July 31, 2009 at 7:11 pm #239333Paul MossbergKeymaster
Yes. You only need one sync tool.
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster
If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)August 1, 2009 at 10:08 am #239334
I thought I was in the TD Registry when I filled out the membership application on this site. However, I don’t see my name listed. When I click on the if not “click here”, I just get the list. How do I register?August 1, 2009 at 10:57 am #239335Rich BellefeuilleParticipant
Just look at the “check list” of info requested (the second post under the list) and Post a Reply with that info.
RichAugust 1, 2009 at 11:05 am #239336
I finally figured it out. I’m not really that stupid. Well!!!!! nearly.
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