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Cal-look/High Performance => Cal-look => Topic started by: nlvtinman on October 22, 2015, 01:41:32 am



Title: Tuning issues with 42 DCNF's
Post by: nlvtinman on October 22, 2015, 01:41:32 am
I am finding the tuning expertise of the 'ole dawg  I am now, not as sharp as 35 years ago. Working on tuning the 42dcnf's on my new 1776, I have both a slight low end bog at acceleration, as well as a stumble when say making a "U'-turn.
Air correction 180
Emulsion tubes f-25
Main 135
Idle 55
Float set at 48-58.5 mm heights, 10.5 range
Heads are ported, 40 X 37.5 valves, port matched manifolds.

I can't find any information in the numerous Weber online forums which notes correction to such problem, and I'm seeking advice on what I can do to make things right. Anyone with the knowledge at the Lounge that can give me guidance? I thank you all in advance,
Steve


Title: Re: Tuning issues with 42 DCNF's
Post by: nlvtinman on October 22, 2015, 12:59:29 pm
58 viewers yet not one shared idea?


Title: Re: Tuning issues with 42 DCNF's
Post by: dive!dive! on October 22, 2015, 13:28:53 pm
Did you check the pump jet squirt is ok and measure the volume delivered ? This can have a huge impact on driveability.


Title: Re: Tuning issues with 42 DCNF's
Post by: Pedalpusher on October 22, 2015, 16:57:15 pm
When making a U-turn, I suppose it is flooding the carbs a little due to the breathing hole of the fuel chamber locating right next and a little above to the main jet stack?

I soldered small copper tubes as an extension for the breathing holes, like snorkels. So I have never had any cornering issues.

ANd you should check what pump jets they have on now, that would give a little information as well.


Title: Re: Tuning issues with 42 DCNF's
Post by: nicolas on October 23, 2015, 04:26:53 am
check for a plugged idle jet. on my DCNFs i never had issues when making U-turns, but the extensions like posted above can make a difference. i don't have them but i have considered them as well.
from memory i had the exact same jetting on my 42's in my 1776. hope it helps.


Title: Re: Tuning issues with 42 DCNF's
Post by: MC Dyno Don on October 25, 2015, 03:58:32 am
I have had similar experiences Steve and would suggest you check the fuel for any water contamination. I recommend you to use some marvel mystery oil in your tank and drive for a day and determine if it solves the problem for you.  Good luck !!


Title: Re: Tuning issues with 42 DCNF's
Post by: Joel Mohr on October 27, 2015, 00:07:35 am
What vents, and what cam? you could have a low vacuum signal...That will do both...