something is not right with the mechanical advance

mr gtx

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recurve distributor has 11* shaft so 22* total. but am down to 8* initial timing giving me my 34* total timing at 3600 rpms. it should be 12* initial giving me 34* total. what am i missing here. had 2 different timing lights on it both reading the same.
 

Boydsdodge

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I mess around with my distributors and others on my Sun tester a bit. Maybe it's the covid but I am not quite following you.
You know that you're after a total of 34 deg. Now lets just say your engine runs great with 20 deg initial, that means we need 14 deg mechanical, 7 deg on distributor.
I would call up mancini racing for a limit plate or the original designer maker of limit plate. FBO Ignition and order.
Hope I helped with brain fog.
 

Toolmanmike

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recurve distributor has 11* shaft so 22* total. but am down to 8* initial timing giving me my 34* total timing at 3600 rpms. it should be 12* initial giving me 34* total. what am i missing here. had 2 different timing lights on it both reading the same.
Dial advance timing light? Electronic advance? Timing tape on the balancer?
 

halifaxhops

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I mess around with my distributors and others on my Sun tester a bit. Maybe it's the covid but I am not quite following you.
You know that you're after a total of 34 deg. Now lets just say your engine runs great with 20 deg initial, that means we need 14 deg mechanical, 7 deg on distributor.
I would call up mancini racing for a limit plate or the original designer maker of limit plate. FBO Ignition and order.
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Hope I helped with brain fog.
OK This from BD makes sense. But the OP I dont get. I am lost on 11 shaft. do you mean advance cam?

What I need
where is your timing at 800 RPM or so for the initial.
What is the total MECHANICAL advance with the vacuum advance disconnected at say 3500
If using a FBO limiting plate which setting?
Also what is the advance cam marked? Say it is 11 and your fbo plate is 13 it will only give you the 11 if that makes sense.

34+/- total mechanical is about where you want to be. what is the total with the vac advance hooked up? Also what is the engine? Any non stock modifications? Points or electronic. And never trust a analouge timing light, but it was the same with two so it prob is close. Trying to help but need the above info.
 
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mr gtx

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let me try to explain. 440 engine. i sent the dist out for a recurve we went with 22* built in mechanical advance coming in at about 1300 rpm and ending at 3600 rpm with vac advance disconnected. there is no fbo plate. pertronix 1 ignition. at 800 rpm am at 8* and at 3600 rpm am at 34* with vac advance hooked up am at 46*. vac is hooked up to ported on the carb. I wanted 12* initial and 22* built in for a total of 34*. i can't swear to it when i first put it in at 12* it was 34* total. it was pinging after a while so i kept backing of the timing to 8* thinking i would be at 30* total but I was at 34* total.
 

'66 Fury I

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I'm old school, old fart. Electronics are great, but the old mechanical ways can eliminate sources of error. If not done yet, verify TDC with a piston stop. To read advance beyond the markings on your timing tab, I would reccommend adding extra marks on your damper. If you turn the engine backwards until the timing mark on the damper indicates 10* advanced and use a center punch to make a mark at 0* (TDC), then move this mark to 10* advanced and put two punch marks at 0* and then repeat again adding three punch marks, you will be able to read to 40* advance with a simple timing light. Add a little white paint in the marks for better visibility.
Might eliminate a possible source of error.
Merry Christmas!!
Lindsay
 

mr gtx

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yes marking the damper will eliminate timing gun error. on tdc part even if the damper marks moved it should not change the spread between initial and total
 

halifaxhops

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OK grasping what you are saying now. Look at the advance cam and what is it stamped at? You need a 13 which is a bit rare to get what you want. 15 is the most common. If it has a 15 you can get UP TP 30 Mechanical 13 gives you 26 which is what you want with initial at 8.. Verify the timing light also as marked as 66 fury's how to above and lets start there. If you do have a 15 or higher advance cam there are two ways of fixing it righ advance cam or a FBO plat. See what you have first.
 

mr gtx

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OK grasping what you are saying now. Look at the advance cam and what is it stamped at? You need a 13 which is a bit rare to get what you want. 15 is the most common. If it has a 15 you can get UP TP 30 Mechanical 13 gives you 26 which is what you want with initial at 8.. Verify the timing light also as marked as 66 fury's how to above and lets start there. If you do have a 15 or higher advance cam there are two ways of fixing it righ advance cam or a FBO plat. See what you have first.
i will pull the dist out and check the advance cam it's suppose to have 11 in there because i told the recurve guy a wanted 12* initial and he said he would put 22* in the dist. could pertronix be mess up and giving me more total timing ? also doe's having only 8* compared to 12* initial really make a big difference for idle or off the line power. it runs really good now hate to mess with it unless the extra 4* really matter.
 

Boydsdodge

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Use a vacuum gauge to find your initial find highest vacuum and smooth idle. Do it with hot engine so you can check for restart dragging. Then back off a couple of degrees.
Unfortunately the weather is not favourable for test drives.
 

Knebel

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The limiter plate is the way to go! I used ot before electronic timing control and its super easy!
 

65sporty

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i will pull the dist out and check the advance cam it's suppose to have 11 in there because i told the recurve guy a wanted 12* initial and he said he would put 22* in the dist. could pertronix be mess up and giving me more total timing ? also doe's having only 8* compared to 12* initial really make a big difference for idle or off the line power. it runs really good now hate to mess with it unless the extra 4* really matter.
I think it would run better with the extra 4 initial, 12 instead of 8
 

mr gtx

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I think it would run better with the extra 4 initial, 12 instead of 8
i sent it back to have the recurve guy check it again. i think some how something is messed up it was suppose to stop advancing at 3600 rpms but it adds another 4* after that. yes 12*-14* initial
 
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