44 IDF Synchronization

I'm having a great deal of difficulty keeping my 44 IDF's sychronized. When I'm floating around 2500 rpm, I get a uneven running of the engine. I bought my Spyder turnkey and I've noticed that the bellcrank on the right carburetor has a long extension on it to allow the down linkage from the cross bar to be in the same position as the left carb. Is this common? It's my belief that this extension is flexing which would cause the butterflies on the carbs not to be in the same position and make the engine run rough.
Is there any mod I can make to the linkage to eliminate this extension?
Thanks for taking the time to look and hopefully respond.

Tom...I'm not familiar enough with these cars yet to know if your problem is in the linkage...But if it is, do I have a deal for you!

Seriously, I have a complete 44IDF Hex Bar Dual Carb Linkage Kit from SCAT...The cross bar and control arms are made of billet aluminum and it seems to be very precise in its operation.

I will be happy to let you have it at the price listed in the SCAT catalog and I'll pay shipping.

You can view it on page 41 of the current SCAT catalog at www.scatvw.com.

Good luck.

To confirm your suspicions, I'd suggest you properly adjust your carbs. Tools needed, (1) airflow meter (Don't waste your money on a Uni-syn, it works, but not as well as a flow meter.

To adjust your carbs, start your engine and let it idle and stabilize. Start with the idle mixture screw located on the outside ottom edge of the carb directly beneath the fuel inlet. This screw has an adjustment spring and is easily damaged if turned "in" too tight. Start on the #1 cylinder and turn the screw in until it lightly stops. The engine will soon start popping and running rough. Slowly, (slowly) turn the screw out until the engine runs crisp. If you over extend the screw, the engine will again falter so start over until correct. Do this to all four cylinders.

Using your flow meter, remove the air cleaners, and stick the meter in each carb. velocity stack. Make sure that each carb is drawing the same amount of air. If not, use the ""idle adjustment screw"" (the screw located on the wide side of the carb next to the butterfly shaft) to run each carb up or down.... Next, run the engine up to 2,500 RPMs and again check. If your linkage is faulty, you'll see a significant difference between carbs.

Another problem could be timing. Run your engine up to around 2,500 RPM's and adjust your timing to a max of 28 degree's advanced. Also, if you have points, the dwell could be off.

On Weber's, there are 2 brass screws parallel and on each side of the fuel bowl inlet. Remove these screws and you'll find the idle jets. They are "'very"" small and easily clog. make sure that the hole is clear and reinstall. Your car is operating off of the idle circut up to 2,500-3,000 RPM's and if they are clogged, it may cause some hesitation and popping.

Larry: I've followed the procedure you have outlined. The car had very little use for a few years before I purchased it. I have replaced the fuel filter several times and even "can-opened" one to see how dirty it really was. There was no major filth and it looked typical. However, I will pull the idle jets and make sure they are clear.

P.S. You're right, I trashed my uni-syn years ago.

Larry, isn't it a good idea to disconnect the carbs from each other when synching idle? Then make the linkage adjust so both carbs are at the same place, i.e. in sync. Then when opening the throttle, engine off, make sure all throats open the same. Try full throttle, see if they all get fully open at the same time. That would clue you in to a mismatched linkage. All links must be very close in length to assure the proper geometry and synchronization. There are some threads on this already at the other spyder site, spyderclub.com.

Daniel,

Sure, that is a good idea, I used to remove the arm on one carb but maybe I've just been lucky as I've been successful in adjusting the carbs without disconnecting the pivot arms. Usually with the minimal amount of slop in the linkage, everything seems to adjust OK

But, you're right, according to the "book" you should remove one linkage arm.

I just went through this in a big way...check your valves and your timing very first - then get into the carb (ask me how I know).

One of the problems Larry pointed out to me was my distributor. My car had been sitting with little use and the grease in the disti had coagulated (can I say that here). It stuck to the weights and the timing wouldn't advance properly. At his advise, I took it out and cleaned it and it helped me complete the process. To check for this condition, hook the timing light up and watch the timing move while you rev the engine form idle to 2500 - it should be a smnooth progression, Mine was not - it held up and jumped around 2000-2500.

I also found that my accel pump settings were off causing me problems at off idle accel.

Once these things were taken care of - setting the synch (which I did AT 2500 rpms) was a snap.

I updated mine with CB Performance weblink and put a new CB linkage on because my old one was flexing and twisting. This made a huge improvement also.

Please post your progress...
Mike

that's because your an experienced professional Larry. Even I know that.

cobra, cobra, cobra (say it like "toga, toga, toga" from Animal House - kinda catchy)

Larry, do us a favor and build a 289 FIA, I think they look better than the 427. Besides, they are rarer, and more Spyder-like(less flares,smaller,lighter).

Daniel, Just for U

Is that the type of Cobra replica you want to get, Larry?

Larry, until then just paint Agatha blue, put the meatballs on her and some side pipes...and of course a saddle.

VROOOOM

That is a nice looking car by the way...

Larry,

Does "Aggie" have a sister?

Tom. Are you loosing power when this happens? Have you taken the car on an extended run at different speeds under load?
The problem may be float level settings. I would take the top off the carbs and check float levels before carb sync.

Aggie has 1 sister but after going to the butcher, she has 2 sides.

John, that photo of the 289 FIA Cobra was for Daniel, I'm still not sure what I want to build, have to sell the Spyder first. Then I'll decide.

Heiko: I rebuilt the carbs, adjusted and sync'd them and installed a new fuel filter. The car ran great at all engine speeds for about 2-1/2 days. Now, when I'm floating around 2500-2800 rpm, I'm getting a slight pop and spitting from the engine. The valves are set per CB's recommendation and I have an electronic points set in the distributor. The timing is set @ 30btdc @ 3000 rpm (also per CB's recommendation).
I'll have to wait until Saturday before I can do any more investigation.
Cheers!

Tom, as Mike mentioned, I recommended that he check his distributor, maybe you should do so.

Another problem could be jetting.

Make sure that those idle jets located parallel and on both sides of the fuel inlet are sparkly clean. Probably wouldn't hurt to make sure the passages are clean by shooting some compressed air through the jet opening.

You could also have too big of a main jet or idle jet or too small of an air correction jet.. or who know's.

A visual inspection of the butterflys will reveal if they are opening correctly, another method is to run up the engine and see if both sides are drawing the same amount of air via the air flow meter.

Depending on the octane you're running, 30 degree's may be too much, more like 28 degree's to be on the safe side.

With the engine ""COLD"" re-check the valves and make sure that they are not tight. If too tight, they could be causing the valves to be open during combustion thus causing backfires. But, it sounds more like a carb problem than a valve problem but worth checking.

Another common problem is that the fuel pump isn't pumping enough fuel and you're running lean. Have you checked your plugs and what color is the exhaust residue in your tail pipe???

If your plugs are golden brown or grey, and your exhaust residue is grey you're too lean. These engines seem to live longer if the plugs are dark and the residue is dark.

A slight overrich condition is much better for an air cooled engine that a lean condition. The extra fuel aids in cooling. Granted you'll get more HP with a lean engine but it won't last.

Tom are your hex arm extensions the same as the ones I have on my Speedster? These flex and make sychronizing quite difficult, I'm about to replace them.

Gentlemen: Thanks for your assistance. I've pulled the plugs and they are a pencil-lead grey color. The valve adjustment is O.K. I do not have the same linkage as the speedster. The hex bar is on the alternator side of the fan shroud. I've determined that the reason that the right carb has an extension on the bell crank is because the intake manifolds are not off set ( the Dellorto's I'm running on my Type-2 have the offset manifolds and do not require the extension). The distributor is advancing properly. I'm running 91 octane unleaded, but I'll try a 28 degree advance. I also need to take the idle jets out and inspect them. As for jet sizing, I had a friend who uses IDF's for all sorts of applications at this altitude (2600 a.s.l.) select the jets for me.
Seeing how the car sat for a few years, I'm thinking about taking the gas tank out and having it cleaned.
Cheers!

Make sure your linkage arms are "geometrically synchronized mirror images" of each other as they undergo their full actuated motion. What can affect this is that the extension piece you are referring to does not accurately place the heim joint at the same distance. Do you have offset or non-offset manifolds-it does make a difference. also, if the rest linkage angles relative to the x,y, and z axis have to be the same but opposite from each side of the engine. It drove me nuts but I finally figure it out by placing a reference plate on the engine rear and took measurements to the joints and bar. Good luck!!

I synch'd mine at 2500 rpm. With the air filter tops off, I was measuring airflow at 2500 and also looking inside when I found an accelerator pump issue. My accel pumps were adjusted wrong and uneven and one was dribbling a little. This helped attribute to my surging at steady state and off throttle - normally around 2500 rpm. I checked the airflow at a few settings up to 2500 to check that the linkage angles were right and things were tracking the same. I used a digial protractor I had to set the angle on the down rods the same to start with.

Ultimately, it was running great until half way through the first drive - the CB Performance arms are soft metal (Al) and the lock screws backed out and the arms moved. I have since use Loctite 222MS and also installed hose clamps on both sides of each arm to prevent them from moving.

Since then, no problems.

Mike

Mike, now that hose clamps are holding them, take out the screw and drill a countersink in the hex rod. Then re-loctite and remove those ugly hose clamps! Have fun, I will be stealing all this info for my trials and tribulations very soon....

That is a good fix. The other problem is that the material is so soft that the theads for the set screws on the linkage arms get wasted if you tighten the set screw too hard.

Mike

Rather than loctite, I have used black or red gasket sealer on the threads of the set screws. It has kept them from vibrating loose, but doesn't prevent them from being easily unscrewed at a later date.

Mike: I took the arms off and checked the dimensioning. No problem there. I need to look at the accelerator circuit to see if it is leaking as mentioned.
The really odd part of all this is the erratic nature of the poor running. Last Thursday (3/12), I drove the car for 60-65 miles and only during the last few miles did the car start to run crappy. The day before, the engine almost died every time I took a corner hard (left, right, didn't matter).
I live in the U.K. 4 out of 5 weeks, so it won't be until the week of 4/11 before I'll have a chance to fiddle with it again.
Thank you for taking the time to offer your help.
Cheers!

My car sat for years and I finally had to repace the carbs - I just couldn't get them to run right after trying everything. I also had to slurry the inside of the tank (I used the eastwood product and it worked great). Now I have a nice running car (so far!).

When you look into your gas tank with a flashlight do you see debris?

Just a few more thoughts...

Mike: There was no debris in the gas tank. But just to be safe, I removed it and had it cleaned. I've been "can-opening" the fuel filters when I replace them to see how dirty they are. All have been very clean. I've also replaced as much of the fuel lines as I can with new. The carbs should be getting clean fuel.
I've rebuilt the carbs using CB Performance's kits, adjusted everything to spec, have all the right jets. It should run fine.
I'm obviously overlooking something.

Have you loked to see if your accel pumps are working properly? that is that they are both delivering the same squirt with no dribbling before or after?

My accel pumps are set right around 30mm of screw length if I remember corectly. That is from the end of the screw to teh closest edge of the nut. I got this measurement from Larry and it came real close - within a turn to being right for me.

Mike

Mike: I'll have to wait a bit. I won't be home for another 2 weeks.

I'm going to swap the carbs in my car for a loaner set (properly jetted and adjusted) to see if I can get the "new" ones to run properly.

END OF STORY!!! Problem solved!!! It turns out that with the car having sat for so long, junk was being sucked from the tank to the carbs (yes, even through filter(s)). Cleaning the tank and installing new hoses did the trick. The car runs absolutely splendid. Life is good. Cheers!