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Join Date: Oct 2004
Location: minneapolis MN
Posts: 463
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Releading and drilling Carb Jets...How?
While I understand and have preformed the rejetting procedure for carbs, what do you do, short of buying new ones if your jets have been drilled too big and you want to fill the holes and re-drill them. I've been told that you have to "Lead them up" and retap them. Can you use solder? probably gets to hot for that? is it actual lead melted over the jet holes? Any old school craftsman out there that know about this stuff?!!
Thanks, Nabil
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'71 S track car, 2.7L & Webers forever! |
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03-25-2009, 12:44 PM
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Location: Portland Oregon
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Nabil,
You will not likely want ot hear this, but drilling, resizing jets is a bad idea in most situations. Its almost impossible to duplicate the factory-spec fuel flow after drilling a jet, much less filling it with a soft metal and resizing it to suit. Given whats at stake, I'd strongly recommend that you get the jets you need and reserve drilling jets to situations when you MUST do some fine-tuning between fixed jet sizes. I've done this before and the results are not always perfectly repeatable.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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03-26-2009, 05:59 PM
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Thanks for the response Steve,
I know what your talking about and I hear you loud and clear. The carbs are zenith 40TIN's and the idle jets are currently drilled to 55's....this is a little fat for the 2.4 E/S spec engine (runds great when its cold out though!) I would like to make them 50's (I did the original drilling from 42.5's to 55's)...I just didn't want to part out my spare set of carbs and wreck original jets....again! I'll keep on looking for a set, but in the meantime, I'm gonna contemplate this somemore! Thanks, Nabil
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03-27-2009, 06:27 AM
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I know where you are coming from. For tuning to get the jets in the ball park, I use a little 4 inch high butane lighter and thin electrical solder. I heat the jet and flow a little solder into the hole. Be gentle and use only a little solder. Then bore out the hole using the weber jet drills.
If you are careful you can create very repeatable results and quickly home in on your proper jet sizes. |
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04-01-2009, 01:25 PM
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Location: minneapolis MN
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Thats the hot tip Matt. Thanks a million. I'll try it tonight.
N
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'71 S track car, 2.7L & Webers forever! |
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04-02-2009, 04:18 AM
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Location: Marysville Wa.
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50 idle jets make for hard cold starting/revving with lots of spit and pop, and low end hesitation on acceleration. try it and see.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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04-02-2009, 08:08 AM
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The 55;s in the 2.4L make it load up at idle and only runs down low really nicely in 33 degree outside temps. The warmer it gets the crappier it starts to run. So the thought was to make those idle jets a touch smaller. John, what would your recommend? Stick with the 55's and the issues that come with them or split the difference (52.5 if that would even be noticeable)??
I'm wide open to suggestions. They are Zenith Carbs going on a warmed up 2.4L N
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04-02-2009, 12:36 PM
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they really are not large enough to cause a load up issue. if the mixture screws are not adjusted properly, it can certainly load up. too high float levels, leaking float valves cause it too. cold temps will cause icing and it can take 1/2 hour before the carbs are warm enough to work right. adjusting the mixture screws when icing occurs is futile. idle it at 1000 rpm when warm and then balance the airflow in all stacks and then turn in each mixture screw until the idle just starts to drop off a bit and then turn them out until to get the best idle without going out any farther than needed. after all six are done, go around a couple more times until just a bit of clockwise (inward) adjustment on each screw will drop the idle a bit, and just a bit outward smoothes it nicely. do it in a quiet place so you can zone in on the engine sound. sometimes i close my eyes to improve concentration.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 Last edited by john walker's workshop; 04-02-2009 at 05:20 PM.. |
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04-02-2009, 04:25 PM
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Location: Marietta, GA
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If you need jets try this guy
I have emailed him pictures of the Zenith jets and we compared notes. We believe the Solex jets can be used in the Zeniths I have not purchased any yet because I don't know what sizes I need (see post in racing and 911 section.) I have some stock 47.5 jets if you want to trade for the 55's. neilca |
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04-03-2009, 05:03 AM
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Location: Marysville Wa.
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same idle jets as vw bug/bus solex carbs.
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04-03-2009, 07:03 AM
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