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BJ8 fuel consumption

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DavidThorn

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I have set the ignition timing on my late BJ8 to 35 max advance at 4000 revs (with vacum tube disconnected) . I have a timing light on which the advance can be set so it should be pretty accurate. But the fuel consumption has now dropped from a regular 24 mpg (UK) to around 20 mpg. Anyone any ideas?
I am confident the carbs are set up correctly all plugs are a nice grey colour. The dwell angle is 35 - not changed.

Before adjustment the car must have been running with the ignition well advanced. The distributor was about 15 degrees further clockwise than it is now.
By the way the car is running fine,a lot less `lumpy` than it was before. Its just the reduction in mpg that concerns me?
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]I am confident the carbs are set up correctly all plugs are a nice grey colour. [/QUOTE]

Carbs a bit on the RICH side, David.

Plugd "shoulb be" tanish.

/bcforum/images/%%GRAEMLIN_URL%%/cheers.gif
Ed
 
I set the timing at 22 to 25 due to the 6500 feet I usually drive in but this weekend I went down to 100 feet and had to adjust bact to 15 becouse I got a surge at the greater advance. Smooth right out with the retarding all the way back home. Go figure. And as Ed says gray is too rich. I would think you would lack power with 35 degrees advanced.
 
By the way the car is running fine,a lot less `lumpy` than it was before. Its just the reduction in mpg that concerns me?
-----------------------------------
More horsepower=higher fuel consumption.
 
tahoe healey said:
I set the timing at 22 to 25 due to the 6500 feet I usually drive in but this weekend I went down to 100 feet and had to adjust bact to 15 becouse I got a surge at the greater advance. Smooth right out with the retarding all the way back home. Go figure. And as Ed says gray is too rich. I would think you would lack power with 35 degrees advanced.
Click to expand...


Watch out TH! David is stating the Maximum advance of the Dizzy at 4000 RPM which is the specified sum of the Mechanical and Vacuum advance at that RPM on the BJ8 engine.---Keoke-?

Well TH, I "Figure" them carbs got enough air down there to last them for ah week or two!---- /bcforum/images/%%GRAEMLIN_URL%%/laugh.gif
 
Ah, thanks, Keoke. 35 did seem too high at 600 to 800 rpm. I've got to try that high rpm timing some time. I think my car likes blue air better than brown anyway.
 
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