Can someone please explain this to me?
Thread Starter
Racer
Joined: Sep 2001
Posts: 352
Likes: 0
From: Alvarado TX
Can someone please explain this to me?
I have read in several threads the concern for running a carburator lean. Damage to cylinder walls, interior parts, and problems associated with overheating. Why? :confused: :confused: :confused:
Thanks in advance!
Steve
Thanks in advance!
Steve
Racer
Joined: Oct 2001
Posts: 271
Likes: 0
From: St Louis MO
Re: Can someone please explain this to me? (woodenichols)
Combustion temps go up when the carb is too lean or there is too much ignition timing advance. This excess heat in the cylinder results in detonation, also called pinging. The pinging noise actually results from the colision of flame fronts in the cylinder. The combustion mixture ignites from the heat before it's supposed to. This is a very violent uncontrolled explosion in the cylinder and can damage the engines internal parts. The incresed heat can also burn valves, melt pistons (not pretty), and cause overheating.
That's my $0.02
Gary
That's my $0.02
Gary
Race Director
Joined: Mar 2001
Posts: 11,322
Likes: 1
From: Living in the Hartland
Re: Can someone please explain this to me? (woodenichols)
Can you have detonation without the pinging? I advanced my timing a couple of degrees with no pinging but am worried that you can have detonation without pinging. I set up my dist 2 years ago and don't remember all the specs (int, cent and vac adv's) but i now it was between 36 and 38 total adv. I had a balancer cover with marks but my new balancer doesn't have a cover. Also not sure if tdc is exact to my balancer mark.
Thanks
Thanks
Racer
Joined: Oct 2001
Posts: 271
Likes: 0
From: St Louis MO
Re: Can someone please explain this to me? (Fevre)
IMHO, the best way to set the car up is with the lowest octane gas you'll be putting in the car. Put in new plugs, set your timing just below the level where it pings. Run the car hard, then check your plugs. You could still be running high combustion temps without detonation, the plugs will let you know.
Gary
Gary
Melting Slicks
Joined: Dec 2000
Posts: 3,407
Likes: 2
From: Carmichael CA
Re: Can someone please explain this to me? (woodenichols)
Ideally, you want the air/fuel mixture to be stoichiometrically correct for the given air temperature present in the combustion chamber at the time of spark. If not then you will get incomplete combustion which means the engine isn't producing as much HP, thus it will need to run at higher RPMs in order to provide the same power output. Friction and heat increase with higher RPMs, and the engine parts will feel more load on them. This will happen with a rich mixture too, it's just that a lean condition is more common as a result of worn vacuum hoses cracking and allowing air into the carburator without first going through the carb venturis and receiving fuel along with it.
