1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

vacuum advance with a dellorto

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Old Feb 25, 2007 | 01:43 PM
  #26  
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From: St Joe MO
Originally Posted by aws140
slacking i was wondering how long itd take you to show up so what advice do you have for me? ill check my carb today and see what i can find.
Not really slacking, don't have an answer for you. The Mikunis I have don't have a vacuum port, so I don't have the advance hooked up. The DHLA I have has no port either. The progression holes are for tuning in smoother transitions when going from the idle to the main circuits.
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Old Feb 25, 2007 | 01:54 PM
  #27  
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I did point out earlier that many sidedraft carbs never had the port for the vac advance, due to their original design as a racing component.
I even when as far as to say "Once (or if) you find" the port needed......
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Old Feb 25, 2007 | 04:12 PM
  #28  
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well now i got the carb installed but the damn thing wont start! ugghh!! it sputters and backfired once, but thats it. its getting fuel, spark, air. the timing is right. i cant tell unless the engine will start. dammit
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Old Feb 25, 2007 | 04:19 PM
  #29  
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From: St Joe MO
Originally Posted by aws140
well now i got the carb installed but the damn thing wont start! ugghh!! it sputters and backfired once, but thats it. its getting fuel, spark, air. the timing is right. i cant tell unless the engine will start. dammit
Clean your plugs and add a capfull of oil down each primary barrel. Installing these aftermarket carbs often lead to flooding when 1st trying to start them up until the fuel pressure gets set.

Originally Posted by Rogue_Wulff
I did point out earlier that many sidedraft carbs never had the port for the vac advance, due to their original design as a racing component.
I even when as far as to say "Once (or if) you find" the port needed......
Sorry if I stepped on any toes, I probably missed what you posted, but you're right. Most of the 'race' carbs don't have provisions for vac advance.
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Old Feb 25, 2007 | 05:38 PM
  #30  
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i poured a cap full of MMO down the primarys and changed the plugs. nothing. wont turn over but back fires a little. i have to go to sleep now for work tonight, 3rd shift. ill have to barrow the parents jeep wrangler to drive....uugghh. i hate that thing. tomorrow ill check the timing. thats the only other place i know to look.
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Old Feb 25, 2007 | 05:47 PM
  #31  
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I never knew that your vacuum advance had to be plumbed in above the throttle plates...

Is there even such a provision on a nikki????
I was sure you just hooked them up to manifold vacuum... isnt that what the emissions removal tutorial says???

Im really confused here....on a stock engine/carb where would the vacuum advances vacuum be drawn from??
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Old Feb 25, 2007 | 05:58 PM
  #32  
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From: St Joe MO
Vacuum advance on the Nikkis is connected to the phenolic spacer plate between the carb and intake. From that port, there are passage ways through the carb that open into the throats where the highest vacuum is pulled, right next to the butterflys, iirc.
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Old Feb 25, 2007 | 08:43 PM
  #33  
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From: Tulsa, Ok.
Originally Posted by trochoid
Vacuum advance on the Nikkis is connected to the phenolic spacer plate between the carb and intake. From that port, there are passage ways through the carb that open into the throats where the highest vacuum is pulled, right next to the butterflys, iirc.
Correct, the port in the spacer goes up, where it meets a coresponding hole in the carb base. If I remember correctly, it's the second port on the spacer (from the front).

Originally Posted by trochoid
Sorry if I stepped on any toes, I probably missed what you posted, but you're right. Most of the 'race' carbs don't have provisions for vac advance.
Didn't step on mine, I was mearly reminding everyone I had already stated the facts. Sad as they are.
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