A/F question
Thread Starter
Burning Brakes
Joined: Feb 2004
Posts: 758
Likes: 14
From: Ville de la Baie Quebec. A winner is just a loser who tried again.
A/F question
I 'm about to calibrate my carb two steps lean from stock, basically to see any performance difference. I tried two steps rich, and obviously not good.
I'm scared stiff about doing heat damage if it is to lean, besides engine temp, is there any signs I should be on the lookout for ?? Is there any way of knowing? I don't have a A/F meter.
I'm scared stiff about doing heat damage if it is to lean, besides engine temp, is there any signs I should be on the lookout for ?? Is there any way of knowing? I don't have a A/F meter.
Race Director
Joined: Oct 2000
Posts: 15,048
Likes: 79
From: central FL, near the beach.
use math.
if 13:1 now
6% leaner
= 13.78:1
will slow slightly, no harm for test
i.e. calculate flow using area formula
if it's 12 now
then 12.72, will go faster
I was so poor as a kid, my 1st car didn't have a master cylinder. u learn to work around it.
if 13:1 now
6% leaner
= 13.78:1
will slow slightly, no harm for test
i.e. calculate flow using area formula
if it's 12 now
then 12.72, will go faster
I was so poor as a kid, my 1st car didn't have a master cylinder. u learn to work around it.
Pro
Joined: Sep 2002
Posts: 690
Likes: 1
From: near Memphis TN
Since no one answered your question I will give it a shot.
Listen carefully for pinging, if it's pinging then it's too lean. Feel for surges while in cruise, is it's surging you are too lean. Look at the plugs carefully, if the ground strap is too white you may be too lean (but plugs may be misleading, depending if you look at them after a WOT run or idle, etc). Look carefully at the white porcelean part for metal flakes, showing detonation, a result of being too lean. Look also at the plug electrode, if it's chalky white that means your engine is running hot (use the same temp plugs you used before you changed the jetting). Look at the temperature guage, being too lean will cause higher temperature.
Now be aware that all these may be indicative of too much timing as well.
Listen carefully for pinging, if it's pinging then it's too lean. Feel for surges while in cruise, is it's surging you are too lean. Look at the plugs carefully, if the ground strap is too white you may be too lean (but plugs may be misleading, depending if you look at them after a WOT run or idle, etc). Look carefully at the white porcelean part for metal flakes, showing detonation, a result of being too lean. Look also at the plug electrode, if it's chalky white that means your engine is running hot (use the same temp plugs you used before you changed the jetting). Look at the temperature guage, being too lean will cause higher temperature.
Now be aware that all these may be indicative of too much timing as well.
Race Director
Joined: Oct 2000
Posts: 15,048
Likes: 79
From: central FL, near the beach.
Originally Posted by Matt Gruber
use math.
if 13:1 now
6% leaner
= 13.78:1
will slow slightly, no harm for test
i.e. calculate flow using area formula
if it's 12 now
then 12.72, will go faster
if 13:1 now
6% leaner
= 13.78:1
will slow slightly, no harm for test
i.e. calculate flow using area formula
if it's 12 now
then 12.72, will go faster
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
For part-throttle operation, you won't damage the engine going too lean. You'll feel other performance issues with the lean condition before you can do any damage. You can get damage if you're too lean at WOT and operate the engine for an extended period at WOT. Otherwise, feel free to experiment and try things out - it's okay!
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Thread Starter
Burning Brakes
Joined: Feb 2004
Posts: 758
Likes: 14
From: Ville de la Baie Quebec. A winner is just a loser who tried again.
Originally Posted by lars
For part-throttle operation, you won't damage the engine going too lean. You'll feel other performance issues with the lean condition before you can do any damage. You can get damage if you're too lean at WOT and operate the engine for an extended period at WOT. Otherwise, feel free to experiment and try things out - it's okay!
