carbs and stalling when coming up to stop sign??

[x98boardwell]

I have a 2.4 twin plug motor.

1) no vacum advance (its centrifical)
2) has dual weber 40's (freshly rebuilt by Paul at Performance Oriented in Chico)
3) electronic Permatune boxes x2
3) 6 PSI fuel pump with Holley fuel pressure regulator. Pressure set to 3.5 psi and consistently stays there

What would cause the car to feel like it is starving when coming up to a stop sign? Sometimes it does it and sometimes it doesn't. I do think the carbs may be a little rich but not quite sure. Could this cause this choking and stalling?

What would be the best way to check CO levels to verify where I should be at and if I'm too rich?

Thanks for the help in advance. Here is the motor.



Thanks,
Bryan

[Eagledriver]

Tuning carbs is an art form. Find someone who can tune them for you.

-Andy

[Evans, Marv]

No idea in your case. I had the same problem with a car I had years ago with Webbers. The culprit turned out to be a pin sized hole in one of the floats causing it to fill and sink. But if Paul did your carbs recently, I doubt that's the problem unless one of yours developed one since.

[Lukesportsman]

Does it die at idle normally or specifically upon rapid throttle closure?

[T77911S]

i would like to see the rest of the car

[x98boardwell]

The car will be sitting there and seem like it resets itself and looses about 250 rpms... just at idle after stopping and sitting, and then right back to normal. It's like the carbs are regrouping or something... sorry for the not so great description. I have to blip the throttle to help.

It does seem like on rapid throttle closure it is more likely to have this issue but even if I am very easy and off the throttle and letting the motor wind down to 1,700 or so before putting in the clutch it can still do it just as easy. Or like I mentioned above, it can do it while just setting there.

Any ideas?

[1QuickS]

What confidence do you have in your distributor? It may be worn and running erratically or the advance may be sticking.

[x98boardwell]

Hey Paul, I wouldn't say that isn't possible... It isn't that old of a distributor but could be a cause. What would be the best way to check this?

The carbs have a definite noise that they make when they reset themselves after throttle... almost like the throttle plates are readjusting (I know I'm saying this wrong) but don't know as my knowledge on carbs is minimal.

[lindy 911]

Try loosening the fuel filler cap and run it that way. I've had problems with a plugged tank vent and had the same symptoms. Also check the float bowl fuel level; it needs to be spot on. Pelican sells a neat level gauge for this very purpose. Have you balanced the carbs yet? This requires another neat gadget Pelican sells and is not that difficult. An AFR meter would help.

[x98boardwell]

The fuel filler on this car is vented and works well. It is a simple click top on the center of the hood. Nothing sealing to tight here at all.

I would imagine Paul balanced the carbs when he rebuilt and dyno'ed them. I would think/hope only fine tuning would be in order. Am I correct on this assumption?

Where would I find these neat gauges on the site?

Thanks,
Bryan

[x98boardwell]

I found the neat tools from our host... probably best to get them so they are on there way.

Is there a technical bulletin on how to use these tools?

[dfhtrhjn]

I had dual webers before had a similar problem. The engine ran well but when I put the clutch in and came to a stop, the rpm would dip way below 1000 and half the time the engine would even die (especially coming off the highway to a stop sign).

My problem was that my idle circuit jets were too small and I was staving the engine of gas under those conditions. I just bought a box of idle jets and swapped them one afternoon until things ran correctly.

What size idles are you running?

[1QuickS]

Bryan,

Your idle jets should be fine; they are 55's.

Pull your idle jets and look through the tips to see if there is any crud blocking them. The jets slip into the threaded holder so you will need to pull them out. You need to look up at a strong light and look from the end with the slits toward the tip.

Although the air cleaners look well installed air can still bypass the seals and bring in dirt that will get into your fuel delivery system. Pull the tops off the air cleaners and see if there is debris on the top surfaces of your Webers. I like to help the sealing efficiency of the K&N filters bu putting a strip of closed-cell, self-adhesive rubber foam around the rubber that the filter is bonded into. The foam makes a VERY effective seal that is compliant to variations in the filter to housing interface.

[x98boardwell]

Paul, can you post pictures of where the idle screws are located? I'm only familiar with the main idle adjustment screw on the ends.

Thx,
Bryan

[1QuickS]

Item #56 on the Weber drawing:Weber 40 IDA Carburetor

The top three brass screws are the idle jet holders; just below the split between the throttle body and the top cover of the carb and above the safety wired hex head grub screws.. Do not tighten too much when reinstalling.

[lindy 911]

Even if built the same, each engine is different and each cylinder is different from one-another. A brand new set of carbs will have to be set-up to the specific engine they will live on as all the cylinders will be slightly different. One of the beauties of the Weber is it's ability to achieve this requirement. The air-flow meter comes with good instructions and is a really neat tool to have in the box. The float level gauge also has instructions included and is likewise easy to use and get the hang of.

[Laneco]

Bryan,

If you want to move the car a bit - Guys' Porsche in San Luis Obispo worked on your spyder. Our car drove perfectly fine - including driving it from Oregon down there. We had tuned it ourselves, using the PMO directions. We had the car running well (much of the issue was linkage geometry).

But Guy took a car that ran fine and made it absolutely sing. I could literally hear the engine come on pitch while he worked on it. Can't say enough good about him.

Plus, he's a fan of spyders with sixes.

angela

[x98boardwell]

Great, thats good news and close to me (just over 2 hours). I may just do that once I do the DIY stuff myself first to get it running cleaner and smoother.

Otherwise, after the rebuild this thing is scary fast and everything else is good. Dry as a bone as well which is nice considering I put it back together. I learned a lot on my last turbo motor. It's no 3.2 but still quick. Thanks Angela.

Paul, I will check those screws and also not install to tight.

Thx to everyone for their input,
Bryan



This was just a few weeks ago when I was putting it back in.

[dfhtrhjn]

Wow that must be really easy to work on. You can practically climb in next to it.

[x98boardwell]

It is easy... but that is with everything off. It does get pretty tight in there once all is installed. But, still easier than a 911 for sure.