Tuning Zeniths for "Rat"

[kkinzli]

Hi guys,

I know a lot has been posted about this but the main link in most of the threads to Garys page is dead. Gary's page is what I used to adjust my carbs about 2 years ago. I just wanted some input on tuning my Zeniths. I am nearing the end of a restoration and want to get my car the "Rat" back on the road hopefully by the 20th of January. If I remember correctly I disconnect the throttle linkage on both carbs. Then turn in all the main screws all the way and back out 2 turns. Turn in all the air adjustment screws all the way. Then set the horizontal throttle screws all the way in and back out 3 turns. With this setting I should be able to get the engine running. Once I have it running I use the synch meter to get cylinders 1 and 4 the same in terms of air flow. Once that is complete get 2, 3, 5, and 6 to match 1 and 4 using the small air adjustment screws. Then check the point gap and timing and repeat the processs. Does this sound right?

Thanks,
Kristoph

[Daves911L]

Kristoph,
Since the Rat has just been sitting, and you have not been playing around with anything in the motor, I would not expect your air flow screws need any tinkering. If the Rat is not running so great, probably your fuel is getting old (it doesn't last very long nowadays) and there might be goo/fod in the idle circuits. Run it good and get some fresh gas in the tank. Pull out the idle jets and clean if necessary, then do your idle mixture adjustment as you know how, by screwing in until that cylinder starts to stumble then backing out to just where it picks back up. Also, make sure point gap and timing are correct BEFORE attempting to make carb adjustments.
DG

[french911]

Hi Kristoph

Try this for Gary's info Zenith Carburettor Manual

Barry

[kkinzli]

Thanks! That is the link I was looking for.

[kkinzli]

Originally Posted by Daves911L

Kristoph,
Since the Rat has just been sitting, and you have not been playing around with anything in the motor, I would not expect your air flow screws need any tinkering. If the Rat is not running so great, probably your fuel is getting old (it doesn't last very long nowadays) and there might be goo/fod in the idle circuits. Run it good and get some fresh gas in the tank. Pull out the idle jets and clean if necessary, then do your idle mixture adjustment as you know how, by screwing in until that cylinder starts to stumble then backing out to just where it picks back up. Also, make sure point gap and timing are correct BEFORE attempting to make carb adjustments.
DG

Thanks for the advice. I think I will have to re-adjust everything. The engine randomly started dying right before Christmas ( I started it often to keep things from gumming up). I started playing with the carbs and adjusting the idle up the other day and still had some issues keeping her running. Also the engine was backfiring quite a bit. My current hunch is that the point gap and timing are off. Something similar happened in ABQ back in 2009. Hopefully I will get a stab at it this weekend.

[Daves911L]

Kristoph,
How long has it been since the Rat got a fresh tank of gas? You wouldn't believe how fast gasoline degrades now. That little tractor I have fires up instantly and idles perfectly on fresh gas. If it sits 3 months with gas in the tank, it won't even hit at all without a shot of starting fluid, and has to be kept on the choke until at full operating temp. It just the lousy quality of modern gasoline. Thank you EPA and corn farmer lobbyists.
DG

[kkinzli]

I poured some fresh gas from a sealed can in there last week. I assume that gas does not go bad if it is in a sealed container. If it does I will have to get some fresh gas.

[dafischer]

Kristoph, I was under the impression that all 69 T's had Webers. Did someone switch your car to Zeniths, or perhaps it was a mid year change since 70's had Zeniths?

Maybe the Brain Trust could chime in here.

[kkinzli]

Somebody switched it to Zeniths. I am not exactly sure what engine I have but I don't have a stamp on the case. Hopefully this weekend I will take off the shroud and get some numbers on the cylinders.

[kkinzli]

Peter and I will be setting the points and timing and tuning the carbs on Sunday. If anyone in South Florida is interested in learning how to do this please shoot me PM

[RWebb]

you could also film it and post on youtube...