Fool proof ways to tune carb by sound/smell/taste?
09-26-2007, 11:31 AM
#11
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Join Date: Aug 2007
Location: sanfranciscobayarea
Posts: 449
RE: Fool proof ways to tune carb by sound/smell/taste?
JMD
quote:
ORIGINAL: Decurion
It take somewhat of a 'tuned ear', but you can set idle mixture just by listening to the engine. Pay attention, and you can hear it speed up slightly or slow down as you turn the mixture screws. It will run the smoothest and fastest when the mixture is right. Also dont forget to keep each mixture screw about the same number of turns out. IE, dont have one screw 5 turns out, and the other 1/2 turn out. It doesnt have to be exact, but keep em close. To help tune your ear, use a vacuum gage to achieve the highest reading. I would also set idle speed down to about 850. Assuming the engine is stock or close to it, it should have no trouble staying running in gear. If you know how to check your timing, it should be around 10-12* with the vacuum advance (the silver can on the distributor with a vacuum hose connected to it) disconnected. Timing will affect your idle speed and quality as well. If the car ran good when you got it, chances are that timing is ok where it is, but probly not a bad idea to at least check.
+1 on all of this....
quote:
ORIGINAL: Decurion
It take somewhat of a 'tuned ear', but you can set idle mixture just by listening to the engine. Pay attention, and you can hear it speed up slightly or slow down as you turn the mixture screws. It will run the smoothest and fastest when the mixture is right. Also dont forget to keep each mixture screw about the same number of turns out. IE, dont have one screw 5 turns out, and the other 1/2 turn out. It doesnt have to be exact, but keep em close. To help tune your ear, use a vacuum gage to achieve the highest reading. I would also set idle speed down to about 850. Assuming the engine is stock or close to it, it should have no trouble staying running in gear. If you know how to check your timing, it should be around 10-12* with the vacuum advance (the silver can on the distributor with a vacuum hose connected to it) disconnected. Timing will affect your idle speed and quality as well. If the car ran good when you got it, chances are that timing is ok where it is, but probly not a bad idea to at least check.
+1 on all of this....
When you say "it will run the smoothest and fastest when the mixture is right", this makes me wonder if it was where it should be when I got it or not. In the first few months I had the car, I would not describe the engine as running fast. It is and was loud and throaty (dual flowmaster 40s) and it had a really nice low grumble.
Now the way I have it, it is a bit faster idle, still a healthy grumble, just idling a little higher and pulling harder it seems. Maybe this is a good thing.
And the car did run good when I got it, but it has always been a pretty rough idle (in a good way, is seems). When I say "rough", it is just that it has a reallllly throaty sound and has a lot more vibration to it than the volvo I was used to driving!!! It just has a lot of pull and wants to GO. The way I have it now, it is just pulling even harder. It is not that it is running poorly, its just that it seems to be tuned more for racing right now than street driving. ...not sure if that is helpful info in any way.
At any rate, I am going to check the plugs today and see what I find. I cant thank you guys enough for all the help you have given me on this. Let me know if what I have said here helps any. Thanks!
-Luke
09-26-2007, 12:02 PM
#12
3rd Gear Member
Join Date: Sep 2006
Location: Sacramento, CA
Posts: 542
RE: Fool proof ways to tune carb by sound/smell/taste?
ORIGINAL: bluovalguy
Buy a vacuum guage ($15-20) and try this:
http://www.fordmuscle.com/archives/2...ockCarburetor/
It is for an edelbrock, but the priciples are the same.
Buy a vacuum guage ($15-20) and try this:
http://www.fordmuscle.com/archives/2...ockCarburetor/
It is for an edelbrock, but the priciples are the same.
Pulling your spark plugs will not change your timing. However, since you asked that question, I figure I better throw in that you can't pull a spark plug while the engine is running. You have to check them when the engine is off. Also, since it takes a little time for the spark plug to actually change color, you really don't get immediate results, plus, you would actually have to use new spark plugs after each adjustment to get accurate readings.
Here is a link on spark plug reading:
http://www.dansmc.com/Spark_Plugs/Sp...s_catalog.html
Good luck!
09-26-2007, 12:12 PM
#13
6th Gear Member
Join Date: Jan 2007
Location: AR
Posts: 5,469
RE: Fool proof ways to tune carb by sound/smell/taste?
If you are happy with the idle, then it will be ok as long as it is not hammering your tranny when you put it in gear. It sounds like you might have a healthy cam in there, if so you may need this increased idle.
We have a fairly healthy cam in the 408, it needs to idle at close to 850 RPM+. The same cam in a 347 would need to have a higher idle than the 408.
We have a fairly healthy cam in the 408, it needs to idle at close to 850 RPM+. The same cam in a 347 would need to have a higher idle than the 408.
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