Carb Linkage

[L8ndeb]

Hello all,

I want to replace the carb linkage that came with the Weber 34ICT dual carb kit. I am wanting to replace it with either an EMPI 17-2945 or a SCAT whose number is I think 30050 or 6061-t6. They both look to me any way to be identical (except for the price). However I wanted to check with the experts here to make sure.

TIA

Leyton in Reno

[L8ndeb]

Anybody??

[MrGoodtunes]

[vwracerdave]

I have used the Scat universal linkage 30050 on a few engines with dual IDF carbs and they worked great. I also feel it is a better system then any of the hex bar linkage systems.

6061-T6 is not a part number. It is the alloy content of the aluminum used in the parts.
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[L8ndeb]

Thanks for the reply Dave. I understand your experience with these is with IDF carbs, any reason it wouldn't work with ICT carbs? Just trying to make sure before I pull the trigger.

[Rob Combs]

Hi L8ndeb, If I can add a bit -

If you already have the complete carb set (manifolds, etc) then try to map out where the carb will sit - how high off the head, etc, and approximate where the linkage arms will fall to establish whether the height will be an issue with hitting the head tins if low or the generator/alternator when mounted high. Then figure out which direction the carb arms want to run to open the throttles and your life will be easier.

I had to reverse the direction the linkage pulled due to my carb setup (throttles opening = linkage swings left, not right). I could have reversed the carbs, but would have introduced other issues so I modded the linkage ahead of time. It was a pain but it worked after adding a pulley to redirect the throttle cable into the relocated linkage arm (sailboat line pulley from the local boat shop). The linkage is far easier to mod to reverse operation if you have access to a lathe, which I do not.

And do keep in mind the linkage will be a fixed length across the engine so it will not be perfect when engine is hot, warm, and cold - you'll have to find its nominal operating temp and synchronize the linkage at that temp. Then live with the slight imbalance at other than nominal temps.

Keeping all of this in mind, it seems to be a good, well-built kit for the $$, has zero play in the metal heim joints, and looks nice when polished up. I'm just getting into the final synch so time will tell if this is the right setup for me but it's looking promising.

Hard to go too wrong for < $100.

Rob

[L8ndeb]

Thanks, Rob, for your insight. Since my original post, I did go ahead and buy it. It did take me a couple of days to do the swap. I've had recent rotator cuff surgery, so that has slowed me down, but the linkage rods had me perplexed for a while. Mine did swing right to open the throttle. However, they didn't open the carbs correctly, in as much, I needed a pull on the passenger, and push on the driver side. I was able to run the longer rod to the passenger side carb, flip the "disk" that slides onto the carb and the linkage rod connects to. So instead of the rod connection being at around 12 o'clock, it was more around 6. Fortunately, the rod did not hit my alternator bracket or tins. That fixed the passenger side.
The bitch was the driver side. The rod, being the top one on the Scat linkage, and the fact I had to flip the "disk" on that one also, had the rod binding on the Scat linkage because of the angle it had to bend to get to the disk connection. After trying every conceivable arrangement, I finally got out my torch and heat the rod up, bending it downward enough at the carb end, to attach to the disk but come straight from the Scat linkage. That eliminated the binding.
It now opens and closes very smooth and effortless. The only thing I'm a little worried about is if I have to adjust the rods shorter, I'm screwed, as they are already there. But the carb idle screws are seated, so I think I'll be okay.
Again, thanks for your insight, and I welcome any thoughts on my post. BTW, what did you use to polish it up?

[Rob Combs]

Glad you got them on there.

Strange idea, but could you have reversed one of the carbs 180 degrees and put the link arm on the side facing rear? Not sure what your clearance looked like between the carb body and shroud if rotated. Or what that would do to your fuel line connections.

I'm doing everything possible to avoid bending to get geometry right, because as you noted, once you bend them you can only adjust length in half-turn-increments at each adjuster, if you bend toward the center and not near the heim joints. Which would be a pain. If you bend too near the heim joint adjusters you might be hosed. I might have to make an intermediate link arm to compound the angle or some other crazy concoction to get mine just right.

To polish, I used flitz, a cheap high-speed rotary tool (think Harbor Freight version of a dremel, about $10) and a polishing wheel. Pretty easy to get those linkage rods and center twist block to shine.

Rob

[L8ndeb]

Ya know, I had already had the fuel lines figured out, and clearance could have been an issue, so flipping a carb really wasn't on my plate.
Actually, the bend I made was about 3" from the heim joint. Not sure what I'm going to do if I have to adjust them at all. However, I don't think I will. I've got a fair amount of travel pushing on the gas pedal. I'm pretty sure it is WOT.

Anyway, good luck with your linkage, and thanks for the tip regarding polishing.

Leyton in Reno

[Rob Combs]

Just curious how your linkage worked out.

I ended up having to much trouble keeping mine synched, I suppose due to no thermostat and too much temp cycling causing the linkage to almost never be the right length - every time the engine grows or shrinks it would pull one carb open ever-so-slightly and my idle would increase, sometimes as high as 2000 RPM, which is unacceptable.

Hats off if you got yours working well!

Rob

[L8ndeb]

Hi Rob,

Well actually, my build is not complete yet. I hope to have it drivable late summer. Gonna be REAL disappointed if it doesn't work. I hope the heat thing doesn't affect me too much. Just wondering, what do people do if it runs well cold, but not when heated, or vice-versa? Adjust them to a middle point and be done? Thinking out loud.

[oprn]

This really confirms the trouble I had syncing the linkage on my Kadrons. There seems to be a hate on for the hex bar type by some guys but my hex bar linkage has never had this problem and is rock steady dependable all of the time at all temperatures! The design eliminates engine growth issues entirely.
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[Matthew]

I have the scat linkage with IDF Webers and have no issues with hot idle. The trick is to get the engine up to operating temp and then adjust the linkage so both carburetors are sitting on the idle stops that were set with a syncrometer with the linkage removed. This has it a little off when the engine is cold but that actually helps bump up cold idle speed. Mine will idle nicely hot or cold.
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[H2OSB]

I suppose this post is pointless other than to offer solidarity to the OP. I have dual 34 ICTs and the Scat bellcrank linkage. I bought the linkage to pre-combat the odd agles caused by the cross bar linkage and the potential, eventual damage to the carb bodies caused by those angles. My engine, though complete, is not in the car yet, but the carbs are on and seem to function smoothly.

H2OSB
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