Opinions On Timing Numbers
07-15-2013, 10:15 PM
#1
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Thread Starter
Opinions On Timing Numbers
I have just got my distributor rebuilt and reinstalled a week ago or so and started playing with the timing. I would like to run manifold vacuum on the advance if I can. I have it set at 17 deg BTDC initial with 36 deg total. So I have 19 deg of mechanical advance coming in at 950-1000 rpm and all in at 2700 rpm. I have limited my vacuum advance to 12 deg at the crankshaft so Im running 48 deg at cruise.
(Question 1.) Is 29 deg advance with vacuum advance hooked up to much at idle?
(Question 2.) I have 11-12 hg of vacuum at idle, 800rpm, so I set my advance to full pull at 10hg and it starts to pull at 6.5hg. Does that sound good to everyone? I still would like to check my vacuum at cruise and heavy/WOT to make sure its not pulling in any when it shouldn't be.
(Question 3.) At first I set my total timing at 36 deg with the springs off the weights in the distributor, so I could do it at idle, and was running just a little over14 deg initial at the time but when I revved the motor up to I noticed the timing backed off about 2-3 deg so I bumped it up to run 36 deg at an elevated rpm(with and without springs on it runs there at increased rpm) and in turn that's where it raised my initial timing to 17 deg and put my timing with vac advance to 29 deg at idle. I just want to make sure that was the correct adjustment in that situation. Thanks a lot for all the help and if anything doesn't sound right please let me know.
(Question 1.) Is 29 deg advance with vacuum advance hooked up to much at idle?
(Question 2.) I have 11-12 hg of vacuum at idle, 800rpm, so I set my advance to full pull at 10hg and it starts to pull at 6.5hg. Does that sound good to everyone? I still would like to check my vacuum at cruise and heavy/WOT to make sure its not pulling in any when it shouldn't be.
(Question 3.) At first I set my total timing at 36 deg with the springs off the weights in the distributor, so I could do it at idle, and was running just a little over14 deg initial at the time but when I revved the motor up to I noticed the timing backed off about 2-3 deg so I bumped it up to run 36 deg at an elevated rpm(with and without springs on it runs there at increased rpm) and in turn that's where it raised my initial timing to 17 deg and put my timing with vac advance to 29 deg at idle. I just want to make sure that was the correct adjustment in that situation. Thanks a lot for all the help and if anything doesn't sound right please let me know.
07-15-2013, 10:41 PM
#2
Melting Slicks
Sounds like you are in good shape. I went through this a couple of months ago and followed Lars instructions and my numbers are in the same ball park with yours (I have 28 at idle with vacuum advance hooked up).
DC
DC
07-16-2013, 06:21 AM
#3
Team Owner
Sounds OK, if the engine is operating fine. If it isn't 'pinging' during acceleration (anywhere in the rpm range), then you should be fine.
If you are getting some pinging at lower rpm, you might want to swap ONE of your distributor springs to the next 'stiffer' one.
If you are getting some pinging at lower rpm, you might want to swap ONE of your distributor springs to the next 'stiffer' one.
07-16-2013, 11:56 AM
#4
Melting Slicks
I have just got my distributor rebuilt and reinstalled a week ago or so and started playing with the timing. I would like to run manifold vacuum on the advance if I can. I have it set at 17 deg BTDC initial with 36 deg total. So I have 19 deg of mechanical advance coming in at 950-1000 rpm and all in at 2700 rpm. I have limited my vacuum advance to 12 deg at the crankshaft so Im running 48 deg at cruise.
(Question 1.) Is 29 deg advance with vacuum advance hooked up to much at idle?
(Question 2.) I have 11-12 hg of vacuum at idle, 800rpm, so I set my advance to full pull at 10hg and it starts to pull at 6.5hg. Does that sound good to everyone? I still would like to check my vacuum at cruise and heavy/WOT to make sure its not pulling in any when it shouldn't be.
(Question 1.) Is 29 deg advance with vacuum advance hooked up to much at idle?
(Question 2.) I have 11-12 hg of vacuum at idle, 800rpm, so I set my advance to full pull at 10hg and it starts to pull at 6.5hg. Does that sound good to everyone? I still would like to check my vacuum at cruise and heavy/WOT to make sure its not pulling in any when it shouldn't be.
At cruise, your vacuum should be well over 16" Hg, so it looks fine. At WOT, your vacuum will be ~1" Hg, so there will not be any vacuum advance contribution, again, you're fine!