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So just for the Heckuvit, I bought a pair of CB Performance "Turbo Hats" for Pearl hoping for a two-part improvement:

1.  Reduce intake noise a little for a quieter cockpit and;
2.  Totally eliminate any chance of rain water getting in to the carburetors

They look pretty sharp in there - A nice, clean look and kinda "Factory":


So after messing with how they mounted and getting a bit of a spacer underneath to raise them a tad, I did a road test and they're all that and a bag of Tostitos.  Very slightly quieter at low speeds and noticeably quieter with your foot way in it to open up the throats.  Not a bad investment.

So with that done and just returning from a road test, I kinda-sorta wondered how close my Carbs were synced.  The last time I bothered to sync them was when I got them back from Blackline Racing after their rebuild and they've been pretty close ever since with minimal fussing, mostly one air by-pass adjustment and idle twiddling.

So I looked at them and thought, "What Would @DannyP do?" and trudged into the shop to get my snail meter.

They were off.  

Not a lot; a needle width difference between #3 & 4, and a needle width left to right at idle.  Not bad, and easily twiddled.  The I reconnected the linkage, ran it up to 3,000 rpm and held it with a special linkage tool I made to hold it running at any speed I want and rechecked it.  I highly recommend wearing combat boots with heavy socks and a pair of long pants because after a couple of minutes of twiddling at 3 grand, your feet get really hot down there.     Anyway:

Wow!  One side was 12 and the other side was barely at 9!    Twiddled the throttle adjustable link on the down side to bring it up and had to re-set it half a dozen times as each time I tightened the linkage locknuts it would change that side again.  Finally figured it out and got everything synced and tight and the idle reset (twice) to boot.  Success!  totally synced and idling at about 800 rpm.  Wrong time of day for a beer, so went inside and had a salad for lunch, instead.

Took it out for a road test and while it wasn't really that far out of sync before I started, you can really feel the difference in a much smoother engine at all rpms.  

THAT's what Danny would do!

(Yeah, Danny....   I know, you're not surprised.  I'm surprised that I had the patience to do it right (for a change)).


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Last edited by Gordon Nichols
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@DannyP - You (and maybe some others) might be interested in the throttle adjustment tool I made.  It attaches to a longer case stud near the distributor/fuel pump block-off plate and uses a CB Perf hex bar throttle lever to move both throttles, equally.  It doesn't care what the engine is or whether sitting mid or rear.

Photos below:

Here's the tool - There isn't much to it.  The throttle lever costs under $15 from CB Perf and I modified it with angle grinder (and went overboard in one spot) to allow it to slip onto the hex bar more or less in the middle.  I drilled and tapped for another set screw against a side flat of the bar (the new screw is lined up with the short end of the Allen wrench in the photo).  I got the knob at ACE Hardware and it screws onto the rod, which is threaded for 10-32 at the knob end, and bent into a loop at the case end to slip onto the stud.  


Here it is installed on the engine.  You can see the new set screw - It attaches in well under a minute.  Simply turn the knob down to increase throttle - It takes only a turn or two to get up to 2 Grand RPM on the engine.  The adjustment rod goes through a barrel fitting (same as on a lawnmower throttle cable - also Ace Hardware) that is just there to guide the rod and keep it from binding.  The bottom of the knob pushes against the top edge of the lever - really simple.  There is a thrust washer under the knob against the lever - just because.


And here's the bottom end of the rod attached to the engine case stud.  It's pretty easy to double-nut the stud, remove it and install a longer one in it's place if what you have isn't long enough - Locktite Blue the new stud going in.  You could also flatten the rod loop a bit to make it thinner, if necessary, but most case studs stick out a bit, anyway.  If you made the rod loop tight to just fit an 8mm stud you just have to anchor it gently for everything to be stable.


Once it's installed, just turn the knob down to advance both throttles equally, just like the cable pulling on its' lever.  You can slowly advance it while watching the tach to get to 2 grand and then it holds it right there for as long as you want (or if your shoes begin to melt while standing in the hot air from the heads).  It'll hold securely from idle to WOT and once set, the rpms stay put - also perfect for setting total advance timing at 3,000 rpm, no?   It also makes starting the engine a bit easier as you can give it a 1/2 turn,  just start it up and then adjust the speed.

This was the third time I've used this tool and I've been impressed with how well it works both times.  Easy to make, easy to use and stable as a rock.


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Last edited by Gordon Nichols

No matter how tight the linkage, there will always be a little slop in there.

At idle, the throttle plates/shafts rest on the idle speed adjustment screws.

As soon as you move the throttles off their stops, the linkage pulls on each throttle(through the cable pull). It is imperative that the actual cable or cable attachment point does the pulling. This replicates what happens when you are driving.

I find it best to have a helper hold the throttle steady, but if that's not possible push/pull from the cable attachment point. Surely a friend or spouse is available for ten minutes or so? Gordon's tool is fine, but I'd like it better if the pull was exactly from the cable. Anywhere else can induce some twist.

Like I said above, 3k rpm isn't necessary, in fact it's better down at 1500-2000 rpm. The smaller the throttle opening they are synched at the better it will be. As the throttle opens synch becomes less and less important. Think about it, at half to full throttle any minor difference is not noticeable. But at a very small opening, any difference in airflow will be noticeable.

Getting it right on makes all the difference. When it's perfect it drives so smooth it can feel like a different car. That is why any and all linkage slop or wear must be eliminated.

Linkage synchronization has nothing to do with which jets are in play, it is ONLY about equal airflow.

Last edited by DannyP

@Gordon Nichols

That is a neat tool you made. I'm sure it works fine because you eliminated 99.9% of slop by using heim joints on the ends of the hex bar.

This is also a good time to talk about symmetric linkage. Both down angles have to be exact for the linkage to work right. Look at it both left and right, the downrods should go straight down, and both be at the exact same angle fore and aft.

You haven't sold me on "the cable is the only way to advance your throttle accurately" thing, Danny.  Mechanically, I see no difference between pulling the cable and rotating the hex bar with my lever so we'll just have to agree to do it each our own way.   I believe that either way will get you a good tune, mine is just more convenient.

One other thing I did a long time ago when fishing a stainless steel nut out of the alternator pedestal (don't ask) was to remove the four studs holding the pedestal to the case and replaced them with bolts.  You can see a couple of those in the third photo, above.  


Because if you want to remove just the fan/alternator assembly, with studs you have to remove the entire fan shroud and that's a BIG DEAL in a Speedster - There is a LOT more vertical room in a VW Beetle to get the fan shroud out.  In a Speedster, it's way easier to drop the engine, and that's a big deal, too.  There simply isn't enough room between the shroud and the pedestal to get the fan past it and you can't lift the fan/pedestal as a combined unit enough to clear the studs.  The only thing to do is remove the fan shroud with the blower attached.   🤮

I had to pull the fan a week ago to check for debris in there and I had it out in less than 15 minutes.  The only thing I had to move was one end of the hex linkage to get the hex bar out of the way and then the four bolts holding the pedestal and it came right out.  (I also pulled #1-2 plug wires at the Disti to give me more room).  You can Locktite Blue the bolts when you put them in, but I didn't bother - They've got lockwashers.

I would highly recommend this, especially to Speedster owners.  It can make life a lot easier for you if you ever need to pull the fan.

@Bobby D asked: "That is some awesome stuff.  I am not sure I understand one aspect of the syncing.  If you get them synced at idle then adjust at higher rpm, doesn't that throw off the idle sync?  Is it a different process at higher RPM if you are on the main jet?"

You don't throw off the main jet.  All you are trying to do is to get the linkages the same length on both sides and the throttle plates at the same angle/position between carb bodies 30" apart - Easy Peasy.  Idle is set on each carb by the idle stop screw.  The Linkages determine how in sync you are once you get off the idle stops.  Two different things.

Danny P has covered this in detail elsewhere, but the way I do this, is to disconnect the down link from the hex bar to one carb to isolate each from the other.   Then I sync both carbs at idle, starting with 1 & 2 or 3& 4 (doesn't matter).  You sync between throats on a single carb by adjusting the air bleed (right next to the mixture screw on a Dell) to get both throats in one carb body the same - Not close, but THE SAME.  Be patient.  Let it settle a few seconds between adjustments.

Once one side is equal front-to-back, do the same to the other side.

When both sides are equal front-to-back and with the linkage still disconnected on one side, adjust the idle screws to make them equal side-to-side between carbs.

Once they're equal between carbs at idle, re-connect the linkage and re-check at idle to make sure nothing has changed.  If it has, figure out which side is off the idle stop and adjust the down-link on that side to make them equal again.

Step back to allow your feet to cool.

Now you're ready to adjust off idle.  Bring the engine up to 2,000 RPM and hold it steady there (that's where my tool helps to give you a rock-steady rpm).  Use your snail to see where you are left-to-right (LTR).  They probably won't be equal so I tend to adjust the lower side up and re-adjust the idle stops later.  That's just me, YMMV.  Adjust one side by loosening the locknuts on the down link and twist the rod to make both sides equal.  Take your time and let it settle between adjustments.

Once you'r equal LTR, tighten the locknuts and re-test.  You'll probably find them out, again, after tightening the nuts, so figure out how to hold the downlink rod still while you tighten the locknuts.  This usually takes a few tries to get where you want to be and some foot cooling time, but you'll get there.

Once THAT is done and you're OK LTR, drop back to idle and recheck.  Usually you find that one throttle lever is off the idle stop, held up by the linkage.  If you're idling high, turn out the stop that's hitting until idles down to your desired idle speed, and then turn in the other side (if necessary) til it touches the lever.  They should still be the same at idle LTR (because you just made the down-links the same in the previous step and you're just making the idle stops match the down-links.  If not, twiddle until they are.

That's pretty much it.

Dual carbs:

You'll have the best luck doing it with the car at operating temperature. Too cold, and your settings will be off.

Step 1: check your timing. Timing is set at total mechanical advance. If you have a vacuum can, remove the hose and plug it. Set the timing to 30* (+/- 2*) total. That might be 2500 RPM, or it might be 3500 RPM - it's all dependent on the kind of day the political prisoner in the Chinese reeducation camp was having on the day he made it. Likewise where the advance lands at idle - it might be 5* BTC, or it might be 10*. You'll definitely like it better if you got a "Wednesday distributor" and it lands at 10* rather than 5*, but you get what you get and don't throw a fit.

Once that's done, you can drop a down link and sync the carbs at idle. The guys that go to 800 RPM have a distributor that idles closer to 10*, the 5* guys are gonna want something around 1000 RPM, otherwise there's a flat spot off idle that no amount of futzing with the carbs will ever cure. Check all 4 holes. If trumpets on the same carb are sucking differently, open the air bleed a quarter turn or so on the low cylinder. Make sure the bypass screw is full closed on the high one. Maybe you'll get lucky and it'll work - it doesn't always (worn shaft bushings or twisted carb shafts are a thing).

Once they're really close, you can just use the number 2 and number 4 trumpets to sync. Get them as close as you can side to side. Once you're there, reconnect the linkage and check again to see that you haven't moved. You haven't really "synced" the linkage yet, but you should be idling like glass.

If nothing moved, you can go to the "just off idle" sync. Danny wants you to use the throttle pull because the hex bar deflects (even if it's ever so slightly) differently pulling from a different spot. I like Gordon's little tool idea a lot, but I'd set it up so it's as close to the actual linkage pull arm as humanly possible. Going off of one drop arm or the other is going to leave you unhappy.

I don't go by what RPM I sync at so much as by where I am in relation to the throttle stops. If I can pull the throttles just off the stops and sync the linkage there - it's perfect.

Here's an insider tip - the drop legs are where everybody gets lost. The heims can be really sticky after a while, and the treads on the drop legs themselves can get nicked up and might not turn freely. The only way this works is if the RH and LH threads move into and out of the heim joints freely and at the same rate, and if the heims themselves have a full range of motion. If one side of the rod wants to thread easily, and the other doesn't, you'll struggle. I run a 10-24 die down the RH threads all the time, but I don't have a 10-24 LH die. I should get one. It's important.

I've gone so far as to fill a hole on a linkage arm with epoxy, then redrill it about 1/16" closer to (or further away from) the hex bar because the total pull wasn't the same side to side. But as everybody keeps saying - once you're past about 1/4 throttle (probably much less), it really doesn't matter that much. It bothers me though. It might bother you too.

Sync-link solves all of the geometry, flexing, slop, and down-link nonsense (of course),  but almost nobody uses it. You probably don't either. Sync-link is a nice bit of kit, but it ain't cheap. The hex-bar linkage can be made to work exceptionally well. It's just more work.

Last edited by Stan Galat

So just for the helluvit, I re-checked everything today.  Full disclosure, after I sync’d everything the other day my idle was around 1,000rpm when it used to be 800 so I figured I would adjust it down.  

Bringing the engine up to 2,000 rpm showed both sides nicely sync’d.  So far, so good.   Dropping down to 1,000 showed a slight (very slight) difference so I checked the angle of he downlinks from the hex bar and fiddled with one to make it straighter (I just used a small carpenter square) and precisely the same as the other side.  That made it more linear for both sides and proved all that stuff Danny has been telling us about getting both linkage links exactly the same in all respects.
(blah, blah, blah….Linkage….Blah, Blah.)    😉

Spent another 2 minutes adjusting the idle stops so they both hit at precisely the same time (I just watch for a slight change on the Snail when turning the adjustment screw) and declared victory.  This suckah is runnin’ great!  

Time for an Allagash beer.

@Stan Galat posted:

Dual carbs:

You'll have the best luck doing it with the car at operating temperature. Too cold, and your settings will be off.

When I got my car it had no oil cooler ducting. I used to try and adjust my carbs and if I both them just right cold, when warm my idle would bump up to 13-1400 rpm. If I adjusted them warm, it wouldn’t idle.

After I installed my CooledOne repro Thing shroud, w/ducting, it was fine. I figure the hot air blowing on the 3/4 side carb was the culprit.


Enjoy your well-earned beer, Gordon.

A few notes:

Sometimes, the simplest things will get in the way of a proper synch.

Most hex bar linkages have six points that must be nearly frictionless if the throttle plates in both carbs are to return to exactly the same place every time you let off the gas — the four heim joints at either end of both down links, and the two pivot points at either end of the hex bar.

Some Tri-Flow (or your favorite elixir) can be your best friend here. One of the worst things about the hex bar linkage is how much opportunity it provides for friction or imprecision. And those six places can easily get gunked up, thwarting all your other efforts.

One more thing:

It's easy to tell if the bottoms of both down links are starting to move at exactly the same time if you don't try to look at both of them at once. Rest a finger of your left hand very lightly on the bottom of the left side link and look at the bottom of the right side link while you pull the center cable attachment point with your right hand. The two sides should move as one piece. If not, get out the wrenches.


So, all this talk of carb whispering takes me back to the first Speedster I had.

It was a CMC, built in SoCal by a guy who subcontracted work to all the usual places. It had a Kirk-n-Mary interior, a quick-n-dirty paint job, and the finest Serrano 1776 money could buy.

Serrano went out of business sometime in the last 20 years, but Steve firmly held down the bottom end of the Type 1 market at a time when the bottom end was right down there. I got invoices with the car - I think the cost for a 1776 with a set of dual 40 IDFs was $1250 or some such thing. It was nothing but the finest - a Cima/Mahle piston/cylinder set, a 110 cam, and an EMPI carb set.

It was my first experience with such exotica, and it was not an auspicious start. I was completely and horribly lost. The CBP Weber "Bible" everybody was toting here was more of a folksy vanity project for the Bob Tomlinson family - it's pretty much useless for anything beyond lining a bird cage.

There were no threads on any of the forums written by people who understood how to set up duals and had a knack for explaining things, so I had no idea where to start.

I turned to AJ Sims (also a darling of this site, back in the day), who sold me a set of his "hot-rod" Kadrons. They were far, far worse than the IDFs - unworkable junk. Art Thraen rescued me by selling me a set of Dellortos set up pretty closely to what I needed, and I applied myself to learning what the heck was going on. I bought an LM1 A:F meter, and ended up buying four of every idle jet CB sold, about 50% of the mains, and a wide range of air-correction jets. It was overkill, for sure - but I was committed. I put CHT gauges on all 4 cylinders, and I could see which idle jet was plugging from inside my car.

I cracked the code by carpet-bombing the problem with time and tools and reading.

Eventually, it just became second nature. I don't need a hundred jets - because 4 or 5 sets will cover 99% of ACVWs out there. Same with mains -  a handful will do it. Air correction is almost never the issue.

Those CHT gauges? A $15 infrared thermometer does the same thing.

I'm self-taught because I had to be. I bought all the tools because that's who I am. Better men than me figure it out without spending a couple of thousand bucks on meters and jets, but that's what it took for me to crack the nut.

I'm not trying to come off as a know-it-all, because I'm the dim bulb in the back of the class who got it done by persistence.

If you can sync your carbs, you're 90% of the way there, and it only takes 50 bucks for a snail and reading and rereading the instructions above and elsewhere.

Step 1: Start off with a Weber kit, not the EMPI clones. Some guys have made the EMPI stuff work - if you're new to all of this, you won't be one of them.

Step 2: Buy the CB hexbar kit, or a sync-link setup. Again, the EMPI stuff can work, but it'll never be elegant and you'll always fight the slop built right in ("EMPI Carb Linkage: The Slop Goes in Before the Name Goes On").

Just say "no". Nay, I say. Nay.

The Scat/CSP/Vintage Speed push-pull linkage is great, but all of the advice is going to be for the CB kit. If "you're on your own" sounds good, knock yourself out.

Step 3: Your carbs are going to come set up jetted fat, but just live with that for a bit. It's the sync where you should start. Follow the instructions above. Valves first, then timing, then sync. Don't hop around. Doing two things at once is a bad way to do this.

Step 4: Once you have a perfect linkage, you can move on to the mixture screws. Start by getting familiar with how to adjust them. I'm oversimplifying it by saying it this way, and I'm definitely not going to say it doesn't matter (it does!) but I will say that even if you're jetted too fat and your mixture screws are backed way the heck out - too rich is better than too lean.

It's important to remember that of the 4 adjustments (valves, timing, sync, and mixture screws) the mixture screws are the least important and the last to get done. They're really only a thing at idle and just off - open the throttle plates much at all, and you start exposing transition ports, which means that needle in that little hole means a lot less.

The operative thing here is to not get lost with where you are. If one screw is good at 2 turns out, and another one is set at 3/4 turn out - something is wrong. There's been a lot written about this - but it's pretty straightforward. Turning the mixture screws in (CW) leans the burn at idle, turning them out (CCW) fattens it up. turn them in at idle until you hear (or see on a tach) the RPM start to drop (lean misfire), then fatten it up 1/4 to 1/2 turn. There are better and more precise methods, but this gets you close.

Step 5: If you've done all this, and you still aren't happy - God love you. You're one of His special children. To go further, you'll need a bung welded in the collector of your header (or just after) and an A:F meter. I have no idea what you should buy, because I bought the LM1 which was state of the art 15 years before I bought it 10 years ago, and it cost about $300. It works perfectly. Somebody out there probably found one on amazon or eBay for $14 and 24 Sam Adams bottle caps, but I'm not that guy.

All I know is that you want a wideband. Narrowband is for folks smarter than guys just starting out, and you're on the front end of this. Just get a good one. If you can't rely on it, you'll be guessing.

There's so much more - but that's the beginning. Get it under your nails, and you'll start wanting more. Before long, you'll be doing the math in your head to figure out what time it is in Mike Pickett's world.

Last edited by Stan Galat

The only thing I'll add to Stan's and Mitch's comments is about the CB hexbar linkage.

I must have gotten two linkage arms made on a Wednesday. These are the arms that slide on the hexbar and contain the downlinks to the carbs. Mine are perfectly symmetrical, I have seen others that are not. Measure yours to make sure(this is important). If they aren't, you can either purchase a new pair or fill the holes with epoxy and re-drill the holes for the downlinks.

The friction Mitch speaks of is non-existent if you replace the ball ends and heavy springs with heim joints(pioneered by RS-60 Mark and I way back in 2006) and light springs. I believe in redundant throttle return springs, I have an extra spring on each side. Racecars have reduntant throttle return springs. It's good safety practice.

Cutting off the tabs on the air filter bases is how the heim joint mod is done. Mill or grind them flat and even. Then drill a hole and install a heim joint. A female 5/16" joint is the perfect height for a Spyder. A male joint and a couple jam nuts may be required for a Speedster, the hexbar needs to be lower to clear the alternator and shroud. I used a thin 5/16" ID coil spring and a couple washers to keep the bar centered. The spring is very short, when the engine is cold it is fully compressed leaving almost no play. Did you know that your engine is almost a 1/4" wider when hot?

On the hexbar itself, you have two choices. You can clean the hole, rough up a piece of 5/16" steel rod and epoxy it in. Or you can tap the hole and use a long 5/16-18" bolt with the head cut off.

Once the location of the aluminum arms is known to be good, I secure them with TWO allen screws. There are two threaded holes in each aluminum arm, one on each side. They are threaded 1/4-20, easy to get extra screws at the local hardware store. I remove the hexbar and drill little countersinks in all the spots where the allen screws touch. I also use some blue threadlocker on the allen screws when assembled. Engines vibrate things loose all the time, especially aircooled ones that occasionally plug idle jets.

I'll add some pics later today when I get outside.

@DannyP posted:

@dlearl476 Try 900-1000 hot. That ends up around 500-600 cold, but after a couple minutes it will be 700 and stay running on it's own.

It’s sussed now with the new shroud. I do 1100 hot, because my oil light flickers below 1050 hot, and it’s fine. Only takes a few seconds of blipping to get it to idle at 800-900 cold.

When I posted previously that it would idle cold, I meant after the initial start period. It would be very lumpy for 10-15 seconds then dies.

Last edited by dlearl476
@Sacto Mitch posted:


It's easy to tell if the bottoms of both down links are starting to move at exactly the same time if you don't try to look at both of them at once. Rest a finger of your left hand very lightly on the bottom of the left side link and look at the bottom of the right side link while you pull the center cable attachment point with your right hand. The two sides should move as one piece. If not, get out the wrenches.


Personally, I think it is impossible to tell with any precision if the side-to-side sync is initiating off-idle with precision by simply "looking" or "feeling".  And, why even "look" or "feel" if you have a 'snail', which is what you should use for adjusting the off-idle progression balance.

The instant of balanced off-idle progression is practically imperceptible to detect by looking or touching.   You do it with the snail.

Your best success will come from sticking with the basics:

1.  Using the snail for side-to-side comparison; adjust the idle balance via the idle adjustment screws with one downlink disconnected.

2.  Connect both downlinks; with idle rpm and balance the same as it was when one downlink disconnected; increase rpm by 300-400 via the throttle cable.

3.  Adjust off-idle progression balance via downlink adjustment by measuring side-to-side comparison with snail.

Now, with idle (sitting on the idle stops) balanced on the snail, and off-idle progression (+300-400 from idle, pulled from throttle cable) balanced on the snail; you are done! 

The only reason to check balance at 2000 (or best at 3000 rpm) is to check for a linkage geometry problem  --  Not to make a downlink adjustment!  If balance is off at 2000 or 3000 then linkage geometry needs to be corrected (one side is pulling non-linear with the other).

I agree with Gordon, the best method to hold an adjustable throttle rpm is via mechanical device (not a foot on the throttle).  I agree with Danny, the mechanical pressure must be applied to the throttle cable (not the linkage).  The hex-bar has significant torsion flex, therefore it is important to apply throttle pressure to the linkage in real-life simulation; via the throttle cable.  I used a small turnbuckle that tensioned on the cable.

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