300 six timing
Cargo Master
Joined: Sep 2007
Posts: 2,095
Likes: 2
From: Wahpeton ND
8 degrees inital seems about right. I use a vaccum gauge as timing lights have never worked very well for me.
I just bump the vaccum up using the distributor and then back it off 1 or 2 inches of mercury. Seems to do the trick damn well. A fellow FTE user taught me this one.
I just bump the vaccum up using the distributor and then back it off 1 or 2 inches of mercury. Seems to do the trick damn well. A fellow FTE user taught me this one.
Posting Guru
Joined: May 2007
Posts: 1,208
Likes: 2
From: North Reading Mass
The fuel pressure at the carb should be 3 to 7 psi. If your fuel mileage is low the float level could be too high or the power (vac) valve could be leaking, among other things.
regards
rikard
regards
rikard
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Junior User
Joined: Apr 2010
Posts: 63
Likes: 0
From: Trinity NC
well ill say 8 is considerably lower than it should be dont you? an thanks for the advice. I just got a new carb and my mechanic says it could be a bad one.
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Cargo Master
Joined: Sep 2007
Posts: 2,095
Likes: 2
From: Wahpeton ND
IF you have a mechanic putting carbs on for you he should be resetting the timing. Everytime you change the fuel curve you need to tune the ignition as well. I would be making him do that as part of the carb installation. I hope he is about 25 years old. Because if he is over 40 he should know this.
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Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
Are you using the stock carb? What year vehicle is this on?
Stock timing for the carb'd 300 was actually about 6 advance. It wasn't a lot.
If you still have the 1bbl, I would say your float setting, as they don't have power valves and such. Just a single metering rod and a jet. The accelerator pump diaphragm could be bad though, which is worth looking in to.
Stock timing for the carb'd 300 was actually about 6 advance. It wasn't a lot.
If you still have the 1bbl, I would say your float setting, as they don't have power valves and such. Just a single metering rod and a jet. The accelerator pump diaphragm could be bad though, which is worth looking in to.
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Junior User
Joined: Apr 2010
Posts: 63
Likes: 0
From: Trinity NC
well the timing mark has evidentally just dissapeared off the harmonic balancer so we have been tuning it by ear. could the cat being stopped up cause this type of thing? it also will rev itself up.
Moderator
Joined: Dec 2007
Posts: 7,987
Likes: 104
From: Boise, Idaho
The timing mark is usually a groove or cut into the harmonic balancer itself, so it may just be filled with gunk or something. Run your hand around the pulley itself, it should be on the lip towards the engine. If you have two marks (like mine did), one will align to the timing marks on the drivers side of the engine and the other on the passenger side.
Revving itself up, if there's no throttle cable binding, can sometimes mean intake leaks. I know when mine had a cracked carb base gasket, it would constantly rev.
A cat usually just causes lack of power. Most exhaust shops will check it for free.
Revving itself up, if there's no throttle cable binding, can sometimes mean intake leaks. I know when mine had a cracked carb base gasket, it would constantly rev.
A cat usually just causes lack of power. Most exhaust shops will check it for free.
Cargo Master
Joined: Sep 2007
Posts: 2,095
Likes: 2
From: Wahpeton ND
Part #39 on that diagram abandoned is a dual use part. When you ram down the pettle it acts as an accelerator pump. It is also vaccum dampened and under high vaccum conditions it pulls the meetering rod down into the jet orafice limiting fuel flow. When vaccum drops the spring overcomes the diaphram and lifts the rod up allowing more fuel to pass through the jet. This is why that meetering rod shaft is so cluttered with springs and such.