[Healeys] Elevation effects on SU carbs - suggestion

[Bob Spidell]

re: 


"Equalize the amount; for instance if it's .055" in one and .045" in the other, equalize at .050"." 


Immaterial and possibly harmful if the fuel levels differ ... start by making sure the float levels in both carbs are correct (but that's carb tuning, not altitude compensation--I was assuming properly tuned and balanced carbs to begin with). Also, make sure the needles are installed correctly (they differ--carb tuning again). 

How would you measure the fuel levels with a dial caliper (half-;) 


bs 



----- Original Message ----- 
From: "Steve B. Gerow" <steveg at abrazosdata.com> 
To: healeys at autox.team.net 
Cc: linwoodrose at mac.com 
Sent: Sunday, May 17, 2009 8:34:03 AM GMT -08:00 US/Canada Pacific 
Subject: Re: [Healeys] Elevation effects on SU carbs - suggestion 

Bob Spidell wrote: 
"Make changes you can remember; e.g. "raised jets 4 flats to lean" and "opened throttles one-half turn." " 

Lin, 
The ace tuners at APT... 
http://www.aptfast.com/index.htm 
...suggest this method: 

Remove the domes and, using a dial caliper, measure the jet depression in both carbs between the bridge and how far down the jet sits. Equalize the amount; for instance if it's .055" in one and .045" in the other, equalize at .050". Make a note of this amount. The difference between the two may turn out to be a _lot_ more than .010". 

In Colorado if you lean it slightly by raising the jets to say. 045" then you can reset them to exactly .050" when you get back to VA. 

I find this method very easy to do using my $14 dial caliper from Harbor Freight. God bless globalization! 
-- 
Steve Gerow 
Pasadena, CA 
BN6 
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