timing
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Joined: Oct 2005
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From: Boynton Beach Florida
timing
my 81 is set at 12 btdc and runs about 20deg. with the vacuum line on..with the vacuum line off it doesn't advance that much more. when I connect the vacuum line it advances to 34 deg. btdc.. Is that right.. I was told with the vacuum disconnected it should advance to 34 -36 deg.
Racer
Joined: Jan 2005
Posts: 365
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From: Glenview IL
Originally Posted by palazzopl
my 81 is set at 12 btdc and runs about 20deg. with the vacuum line on..with the vacuum line off it doesn't advance that much more. when I connect the vacuum line it advances to 34 deg. btdc.. Is that right.. I was told with the vacuum disconnected it should advance to 34 -36 deg.
Are you saying that it doesnt advance when you bring the RPMs up with the vac can disconnected??? I think this is what you mean. If so, my guess is that your mechanical advance is at fault. Check Lars' paper on timing and I think he also has one on dist rebuilt. Looks like its time to pull the dist and give it a good once over.
~Rich
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Joined: Dec 2002
Posts: 560
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From: Mooresville NC
I'll be following this one. I have had the same issue with my '79 and swear it's causing most of my overheating issues by running retarded. With the timing set at 16 deg, with the lightest advance springs, the total timing I would get wouldn't be more than 26 deg. And Yes, I checked TDC with the balancer and it was correct.
A while back, Lars had prety much confirmed something I found on a HotRodders forum that some of the "emission years" HEI distributors limited the total advance of the HEI distributors. I don't think you can do much about it except buy an after market HEI or recureved distr.
Good Luck.
A while back, Lars had prety much confirmed something I found on a HotRodders forum that some of the "emission years" HEI distributors limited the total advance of the HEI distributors. I don't think you can do much about it except buy an after market HEI or recureved distr.
Good Luck.
Thread Starter
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Joined: Oct 2005
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From: Boynton Beach Florida
it does advance a little matybe 5or6 degrees with the vacuum disconnected. its also a after market distributer HEI with a vacuum advance.. IT does get 34 degs with the vacuum connected
Melting Slicks
Joined: Aug 2003
Posts: 2,135
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From: Dayton Oh
Sounds like the mechanical advance weights are hung or you've got a really, really strong set of advance springs. Have you pulled the distributor cap and checked to see if the weights move freely?
