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Old 11-08-2019, 04:51 PM   #1
Gotthebug
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Default Advice tuning carbs please

About to tune my twin weber 48 IDF's on a 2276 engine.
Looking for advice as to what readings I should get on the carb balancer and other general advice.

STRONG smell of petrol after use and can smell fuel when running - maybe running too rich??? How can I tell when the mixture is right?

Reason for checking carbs is I'm getting popping/banging from exhaust when I back of from accelerating. Engine pulls fine but need to stop the pop!
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Old 11-08-2019, 07:26 PM   #2
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Quote:
Originally Posted by Gotthebug View Post
About to tune my twin weber 48 IDF's on a 2276 engine.
Looking for advice as to what readings I should get on the carb balancer and other general advice.

STRONG smell of petrol after use and can smell fuel when running - maybe running too rich??? How can I tell when the mixture is right?

Reason for checking carbs is I'm getting popping/banging from exhaust when I back of from accelerating. Engine pulls fine but need to stop the pop!
Best way to get it sorted is booked into a rolling road as the other jetting may be incorrect. But at home

Start the engine and let it idle. Then tighten the mixture screw, all the way until the engine starts to cough, you should hear it drop in RPM. Then turn out slowly until it picks up and runs smooth you want it where its running the best, you will be able to hear when its right. If you carry on backing the screw out it will run poor again so find that sweet spot inbetween. Repeat this for all of the mixture screws one at a time. Try and count how many full turns it takes for it to run best as this will give you a indicator if your idle jets are too small or large


Once you are happy with the mixture screws, you can readjust your idle

You can pull your spark plugs and have a look at the ends and that will give you a indication if your running rich
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Old 11-08-2019, 09:29 PM   #3
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what reading should I have on the carb balancer (snail) for 2276 engine?
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Old 11-08-2019, 10:05 PM   #4
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Ive heard that if they are set equal it doesn't really matter.
Got a similar problem as you on my Escort with twin 40s.
Mine is off to Northampton Motorsport on the 28th for a set up and rolling road session.
No point in trying to set em up if its just guesswork.
And theres no point of having a modified engine and not having it set up properly to get full potential.
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Old 11-08-2019, 10:27 PM   #5
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Quote:
Originally Posted by Hoosier View Post
Ive heard that if they are set equal it doesn't really matter.
Got a similar problem as you on my Escort with twin 40s.
Mine is off to Northampton Motorsport on the 28th for a set up and rolling road session.
No point in trying to set em up if its just guesswork.
And theres no point of having a modified engine and not having it set up properly to get full potential.

Yeah, with the snail meter just get them set up the same. I think 5-7 would be about your idle. Also do not rev the engine with one fitted as it will 99% break the gauge as the needle can go all the way round.

Hoosier, i have used Northampton Motorsport twice now, they are really good and indepth
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Old 11-08-2019, 11:29 PM   #6
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A very good site.
http://www.aircooled.net/vw-carburetors-jetting-102/

http://www.aircooled.net/synchronize...rburetors-103/
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Old 12-08-2019, 09:19 AM   #7
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Cheers everyone
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Old 12-08-2019, 12:18 PM   #8
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Fitting an Air Fuel Ratio (AFR) gauge kit and lambda sensor , will enable you to see what is happening with the jetting and mixture as you drive it and as it is permanently fitted you can see if you have a problem such as the carb leaking fuel into the engine. Plus if you make a Venturi change you can use the afr gauge to adjust the jetting yourself. It'll be cheaper than a rolling road session.
VW Speedshop has a couple of kits listed.
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Old 12-08-2019, 01:22 PM   #9
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Take it to Ricky Gauld near Huntly http://www.rickygauld.co.uk/index.html
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