How to recurve dizzy?
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Elder User
Joined: Jan 2002
Posts: 525
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From: Mansfield, Texas
How to recurve dizzy?
In my 390 I have a new stock dist. from Auto Zone. I have my initial timing set @ 10 btc. I have searched and read on the subject of total advanced timing.
1)To my understanding, the motor is rev'd up to 2500 rpm's and the total timing from reading with a timing light should be (predetermined #) 30 - 35 btc or so.
2)By changing the spring sizes on the advance plate this will allow the advance to come in sooner or later. The heavier the spring the advance comes in at a higher rpm.
3)Also, what are the benefits of having your advance come in sooner or later?
Thanks Robert P.
1)To my understanding, the motor is rev'd up to 2500 rpm's and the total timing from reading with a timing light should be (predetermined #) 30 - 35 btc or so.
2)By changing the spring sizes on the advance plate this will allow the advance to come in sooner or later. The heavier the spring the advance comes in at a higher rpm.
3)Also, what are the benefits of having your advance come in sooner or later?
Thanks Robert P.
Postmaster
Joined: Jul 2003
Posts: 3,934
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From: iowa
Sounds about right but i don't think the adavance is fully in until 3500rpm or so. The are weigts inside the dizzy marked 13L and 18L or 16L and 21L. Say up the spring is hooked to the 13L weight you will double that and have 26 degrees of mechanical advance. My dizzy happen to have the 16L weight and i get 32 degrees of mechanical advance. remember there is three sources inital, mechanical, vacuum. as the throttle is pressed you have your inital 10 degres + ?mechanical+?vacuum. AS the the full mechanical advance kicks in say you have the 13L weight you should have say 36 degrees at say 3500 rpm and the vacuum signal should by about nothing. Now what people try to do is bring the timing in as quick as possible without denotation. If you can get your mechanical in by say 2500-2800 you will be able to make more power and accelerate you vehicle quicker as long as it doesn't denotate. The lighter the springs used the quicker the advance curve is and the quicker the mechanical advanced is maxed out. Hope this helps some.
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Elder User
Joined: Jan 2002
Posts: 525
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From: Mansfield, Texas
fordeverpower, it did hellp on theory of how advancing works.
I did read somewhere that the weights will fully open at about 3500 rpm's. Would I be correct in saying that all that is needed for advancing timing is :
a) Knowing where I want my advanced timing to come in @. Let's say I want it @ 32btc. I need to mark my balancer (correctly) up to 30btc.
b) Knowing where I want my rpm's to be when this happens. Let's say 2800 rpm's.
c) With the engine @ running temp. The base timing @ 10btc. Using 2800 rpm's as my advanced timing mark. Run the motor up to 2800 rpm's and check the timing on the balancer. If the mark is reading higher than my 30btc mark, then I need to install a lighter spring; so that with the lighter spring the next time I check the advance timing it should drop the mark closer to my 30btc mark.
Thanks Robert P.
I did read somewhere that the weights will fully open at about 3500 rpm's. Would I be correct in saying that all that is needed for advancing timing is :
a) Knowing where I want my advanced timing to come in @. Let's say I want it @ 32btc. I need to mark my balancer (correctly) up to 30btc.
b) Knowing where I want my rpm's to be when this happens. Let's say 2800 rpm's.
c) With the engine @ running temp. The base timing @ 10btc. Using 2800 rpm's as my advanced timing mark. Run the motor up to 2800 rpm's and check the timing on the balancer. If the mark is reading higher than my 30btc mark, then I need to install a lighter spring; so that with the lighter spring the next time I check the advance timing it should drop the mark closer to my 30btc mark.
Thanks Robert P.
Postmaster
Joined: Jul 2003
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From: iowa
A) yes you will have to mark the balancer at 32 if thats what you want. I know they only go to 30 btdc.
B) Pick a intended rpm like 2800 or whatever you want. Using a tach while doing this is best or find a way to maintain that rpm that is desired.
C) This is a bit trickier because most people that recurve the dizzys use inital and mechical only. There will most likely be a little vacuum signal under part throttle acceleration at 2800rpm. THe easiest way to do this would be to unplug the vacuum advance and not use it. Otherwise I would unplug it to pick the springs and then later hook it up and see if or how much past 32 degrees you have at 2800. You should as with most others be able to run 36-40 total adavance. So if you had your 6 degrees inital and found the springs for 32 at 2800 but have more timing with vacuum advance hooked up you could allow up 40 total meaning the vaccum would add 8 to your 32 with plugged vacuum advance.
D) bottom line this takes time!
B) Pick a intended rpm like 2800 or whatever you want. Using a tach while doing this is best or find a way to maintain that rpm that is desired.
C) This is a bit trickier because most people that recurve the dizzys use inital and mechical only. There will most likely be a little vacuum signal under part throttle acceleration at 2800rpm. THe easiest way to do this would be to unplug the vacuum advance and not use it. Otherwise I would unplug it to pick the springs and then later hook it up and see if or how much past 32 degrees you have at 2800. You should as with most others be able to run 36-40 total adavance. So if you had your 6 degrees inital and found the springs for 32 at 2800 but have more timing with vacuum advance hooked up you could allow up 40 total meaning the vaccum would add 8 to your 32 with plugged vacuum advance.
D) bottom line this takes time!
Senior User
Joined: Sep 2000
Posts: 435
Likes: 1
From: Central Oregon
I had a man by the name of Faron Rhoads on the FordFE.com forum re-curve the dizzy in my 410. He's really up on what the various FE combos "like", so might be worth checking out.
I'm now running with 24 degrees initial timing, and only 14 degrees mechanical advance coming in by 2900 RPM(he narrowed the slot considerably on the dizzy reluctor), and vacuum of 10 degrees at 15" vacuum. It really smoothed out my engine and made it come alive. I'm only running a speck over 9:1 CR since it's primarily used heavily loaded, so am able to get away with that much initial, but if yours is a higher CR you might have to step back a little on initial timing. But in general the FE's like lots of timing coming in pretty early on. And I think it's a rare person with the patience to get a really smooth advance curve by tuning on the vehicle, you really need to get the dizzy on a machine.
JFWIW. Steve
I'm now running with 24 degrees initial timing, and only 14 degrees mechanical advance coming in by 2900 RPM(he narrowed the slot considerably on the dizzy reluctor), and vacuum of 10 degrees at 15" vacuum. It really smoothed out my engine and made it come alive. I'm only running a speck over 9:1 CR since it's primarily used heavily loaded, so am able to get away with that much initial, but if yours is a higher CR you might have to step back a little on initial timing. But in general the FE's like lots of timing coming in pretty early on. And I think it's a rare person with the patience to get a really smooth advance curve by tuning on the vehicle, you really need to get the dizzy on a machine.
JFWIW. Steve
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Elder User
Joined: Jan 2002
Posts: 525
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From: Mansfield, Texas
Thanks Steve. I'll have to search around here for someone who has the capibility to do this.
I have this to take care of and to install an o2 sensor with a gauge. I want to see how much fuel efficiency I can get out of my setup.
Thanks for your reply.
Robert P.
I have this to take care of and to install an o2 sensor with a gauge. I want to see how much fuel efficiency I can get out of my setup.
Thanks for your reply.
Robert P.
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Needsmorecoffee.
Joined: Oct 2004
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From: CT
I'll second Faron Rhoads and he does excellent work and I have one that is going his way as well. G.
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