Time to Connect

[mike4gtl]

I have been struggling to accelerate these last few weeks away from junctions and pulling up through the gears was getting to be a nightmare. I found out that pulling the choke out a helped as it turned back into the usual little racing car.

I have now connected the air cleaner pipe to the exhaust flange and all is much better but i do notice a drop in performance when pulling up the gears and a touch worse on fuel.

I assume it shudders because it has no accelerator pump?

 

[Cornish4]

Hi Mike, I had the same trouble with my car when it had the Zenith 28IF carb. Try opening up the main jet to 1mm from .9mm, which it probably is now. This should make a difference, without increasing the fuel consumption, and save you using the choke when under-way.

 

[malcolm]

Failed vacuum advance can cause those symptoms. That's my guess. Femsa?

The winter air intake position can cause the trouble too. Also vacuum leaks or a missing restrictor to that connector to the inlet manifold.

 

[Cornish4]

I hadn't realised the winter air intake setting can cause these problems too Malcolm. My 4, now fitted with a Zenith 32IF7 idles roughly after a run, but switch off and start up after a few minutes and it ticks over smoothly, any ideas why this should be? I have it on winter setting of course at the moment.

 

[mike4gtl]

Last year when I bought it I carried your Malcolm's repair to the femsa vac advance by replacing the rubber with an inner tube. This still works! All air pipes are clear as the revs drop when I did connect the restrictive one. Not checked for air leaks yet though. I might drill the jet then.

 

[mike4gtl]

Mine runs much better on the winter setting. No judder or flat spot. But the response is worse than the summer setting

 

[Cornish4]

It was Derek at Renospeed that recommended drilling out the main-jet Mike. I didn't have any air leaks as such, all faces and gaskets ok, but I guess there was play in the spindles and air was getting in. This fix did the trick though. I can't try the carb on summer setting yet, bloody cold down here in oggyland at the moment.

 

[angel]

As the main jet is a real restriction roughly on the second half of the throttle travel, an equally good (or sometimes better) way to enrich the mid-range and pickup is to raise the fuel level by placing a thinner washer under the float needle valve. 0,5 to 1mm is enough at most cases.