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Re: Vibration at 2500 rpm [Re: pjc360] #2367292
09/08/17 01:34 AM
09/08/17 01:34 AM
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first we gotta find if the phasing is too far in front of or too far past the cap terminal. Ideally you want the rotor at or near the trailing (far) side of the cap terminal when it fires as RP will pull it back the other way (against rotation). If Ricks reluctor has the multiple roll pins holes & I believe it does then it simplifies things as one of those holes is for sure gonna make the RP line up but there is plenty of material there for the same # of holes for us to drill to get it right, just takes time & some carefull eyeballing/measureing then drilling. On the timing, Say a can offers 22 (crank) degrees, going CCW makes the can require more vaccum for the can to start offering its advance amt from zero/& a higher vac # for the slope to max out at its max 22 degrees of added advance. If going CCW, the slope (amt of advance) is the same, just starts later/maxes out later (later being a higher in hg #) EDIT so I was wondering if the can was fully deployed (max vac) the 2nd time when it missed less after turning it CCW cuz if it was then RP arc distance would have been maxed out in both cases (to further pin down if too much timing is a factor).

Last edited by RapidRobert; 09/08/17 11:36 AM.

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Re: Vibration at 2500 rpm [Re: RapidRobert] #2367390
09/08/17 11:40 AM
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Originally Posted By RapidRobert
first we gotta find if the phasing is too far in front of or too far past the cap terminal. Ideally you want the rotor at or near the trailing (far) side of the cap terminal when it fires as RP will pull it back the other way (against rotation). If Ricks reluctor has the multiple roll pins holes & I believe it does then it simplifies things as one of those holes is for sure gonna make the RP line up but there is plenty of material there for the same # of holes for us to drill to get it right, just takes time & some carefull eyeballing/measureing then drilling. On the timing, Say a can offers 22 (crank) degrees, going CCW makes the can require more vaccum for the can to start offering its advance amt from zero/& a higher vac # for the slope to max out at its max 22 degrees of added advance. If going CCW, the slope (amt of advance) is the same, just starts later/maxes out later (later being a higher in hg #) EDIT so I was wondering if the can was fully deployed (max vac) the 2nd time when it missed less after turning it CCW cuz if it was then RP arc distance would have been maxed out in both cases (to further pin down if too much timing is a factor).


Gotcha, I'm gonna start on it tonight after work. I'll modify a cap with a hole and watch the rotor with the vacuum advance connected.
Then I'll bring distributor timing only up to 46-48 to 2500 and see if the issue is still there.
Cause that's about where it is with vacuum advance hooked up

Re: Vibration at 2500 rpm [Re: pjc360] #2367456
09/08/17 02:13 PM
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yes, freeze the rotor with the light while idling with the can hooked and unhooked & see how far the rotor swings between the two. then at 2500 with the can plugged in, get the timing where it was when it was missing, then unplug the can/cap the carb nipple & twist the dist to get the timing back to the same #/same 2500 RPM & see if it misses or not.


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Re: Vibration at 2500 rpm [Re: RapidRobert] #2367920
09/09/17 03:00 PM
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Originally Posted By RapidRobert
yes, freeze the rotor with the light while idling with the can hooked and unhooked & see how far the rotor swings between the two. then at 2500 with the can plugged in, get the timing where it was when it was missing, then unplug the can/cap the carb nipple & twist the dist to get the timing back to the same #/same 2500 RPM & see if it misses or not.


I'm getting started on this this morning.
I did some reading on rotor phasing on the small block distributors last night, and it's said that since the small block distributors spin clockwise you should always start with a slot
That's machined after a reluctor tip. Ether 5-10-15 degrees after a reluctor tip.
I'll report back soon with my findings.

Re: Vibration at 2500 rpm [Re: pjc360] #2367944
09/09/17 04:13 PM
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Ok rapid Robert, I got a hole drilled in an old cap and put it on and checked the rotor phase with and without the vacuum advance and the rotor phase is off with and without the vacuum advance, it's not as far off without the vacuum advance but it's still not directly under the cap tower.
I took a black marker and marked where the cap terminal is and where the rotor is with just mechanical advance no vacuum advance and where the rotor is with vacuum advance.
The rotor is behind, it needs to come forward more to be under the cap terminal.
I took a picture of the cap with the marked locations of where the rotor is.
But I can't figure out how to post the picture on this page.
Idk what a URL is and how to get one.


Last edited by pjc360; 09/09/17 04:35 PM.
Re: Vibration at 2500 rpm [Re: pjc360] #2367957
09/09/17 05:07 PM
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Here is the photo of the distributor cap marked with where the rotor position is.furthest to the left is where the cap terminal is, the mark in the middle is where the rotor is with just mechanical advance, the mark furthest to the right is where the rotor is with vacuum advance.


IMG_2632.JPGIMG_2632.JPG
Re: Vibration at 2500 rpm [Re: pjc360] #2368010
09/09/17 08:27 PM
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Do I have to make a new hole in the reluctor for the roll pin a little ahead of the original hole or a little behind the original hole to get the rotor to come forward more?

Re: Vibration at 2500 rpm [Re: pjc360] #2368051
09/09/17 10:06 PM
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looking down at the reluctor, make a new hole maybe 10 deg CCW from the orig hole. cap bulge to cap bulge is 45 deg so from your sharpie marks it might even take 15.


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Re: Vibration at 2500 rpm [Re: RapidRobert] #2368056
09/09/17 10:19 PM
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Originally Posted By RapidRobert
looking down at the reluctor, make a new hole maybe 10 deg CCW from the orig hole. cap bulge to cap bulge is 45 deg so from your sharpie marks it might even take 15.


Thank god you replied!!! I've been wanting to hear which way to try a new locating hole, so my next question is how do I measure in degrees to get the spot at least some what close?
How far apart is each tooth on the reluctor roughly? That would give me a good starting point on how far it needs to be.
I'm going to the hardware store with my digital micrometer to measure out different sized drill bits to use on making a new hole and I bought 2 other reluctors to have as spares in case I botch one of them

Re: Vibration at 2500 rpm [Re: pjc360] #2368064
09/09/17 10:38 PM
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each tooth on the reluctor is 45 deg apart the same as it is on the cap bulges (just around a smaller dia circle). Here's a pic with all of em drilled (I ain't mini rattail filed out to the ID yet on all of em). The OE (2) holes are very close to 6/12 as I have it clocked in the pic. EDIT After more eyeballing & I might be turned around on the CCW, it might be CW.

SAM_0813.JPG
Last edited by RapidRobert; 09/09/17 10:45 PM.

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Re: Vibration at 2500 rpm [Re: RapidRobert] #2368077
09/09/17 11:08 PM
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Originally Posted By RapidRobert
each tooth on the reluctor is 45 deg apart the same as it is on the cap bulges (just around a smaller dia circle). Here's a pic with all of em drilled (I ain't mini rattail filed out to the ID yet on all of em). The OE (2) holes are very close to 6/12 as I have it clocked in the pic. EDIT After more eyeballing & I might be turned around on the CCW, it might be CW.


So your thinking I need to do a new hole 15 degrees clockwise from the original
Hole?
I read on Rick ehrenbergs instructions with his multi indexed reluctor that on small
Block distributors that rotate clockwise you want to use a slot that's behind a tooth.
Wether that is clockwise or counterclockwise to the original slot I'm not sure?
Also what is a mini rattail and where would I find some? Are they are the hardware stores?

Re: Vibration at 2500 rpm [Re: pjc360] #2368086
09/09/17 11:41 PM
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What size drill bit for a 6/12 hole?

Re: Vibration at 2500 rpm [Re: pjc360] #2368092
09/09/17 11:49 PM
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the mini files usually come in a pkg with a bunch of em (half round half flat full round etc) & the one you wantin the pkg is round/tapered like a rats tail. I'd say do some carefull visual on the arc distance & actually there is plenty of material to drill several holes in each one like Eberg did on his. The goal is to have the rotor/cap interface, the rotor at the trailing (CW) edge of the cap terminal as the RP change from the can will swing it back CCW on a SB. I cant say for sure on the 15 deg, just visual and measure & it may take several holes to get it dead on. Keep in mind the rotor terminal is .244" wide & the cap terminal width is .214" so you have some leeway. the goal is to get that distance as close as possible including radial rotor tip to cap clearance (lengthening the rotor blade might be needed also) in addition to the around the circumference distance we are working with right now. EDIT the holes at 6 & 12 o'clock are the OE holes & the top one looks like a square but that is camera distorsion & it is round like the 6 o'clock one. MORE EDIT I would take the reluctor with you to the hardware store & get a drill bit to match the current holes as that is the roll pin size you will be (re)using.

SAM_0814.JPG
Last edited by RapidRobert; 09/10/17 11:14 AM.

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Re: Vibration at 2500 rpm [Re: RapidRobert] #2368109
09/10/17 12:39 AM
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Originally Posted By RapidRobert
the mini files usually come in a pkg with a bunch of em (half round half flat full round etc) & the one you wantin the pkg is round/tapered like a rats tail. I'd say do some carefull visual on the arc distance & actually there is plenty of material to drill several holes in each one like Eberg did on his. The goal is to have the rotor/cap interface, the rotor at the trailing (CW) edge of the cap terminal as the RP change from the can will swing it back CCW on a SB. I cant say for sure on the 15 deg, just visual and measure & it may take several holes to get it dead on. Keep in mind the rotor terminal is .244" wide & the cap terminal width is .214" so you have some leeway. the goal is to get that distance as close as possible including axial rotor tip to cap clearance (lengthening the rotor blade might be needed also) in addition to the around the circumference distance we are working with right now. EDIT the holes at 6 & 12 o'clock are the OE holes & the top one looks like a square but that is camera distorsion & it is round like the 6 o'clock one. MORE EDIT I would take the reluctor with you to the hardware store & get a drill bit to match the current holes as that is the roll pin size you will be (re)using.


Based off the measurements of the roll pin that holds the reluctor to the shaft I got a 3/32 drill bit, I will need to get a rat tail file in the morning.
So I am still confused as to wether or not I need to go clockwise to the original hole or counter clockwise to the original hole?
I'm going to get it started on it all first thing in the morning.
I already have a rotor that has a longer tip on it, the firecore distributors come with a rotor that has a longer blade then stock on it.
So I have the drill bit I need and the drill and a vice I will get a rat tail file in the morning, I just need to know if I'm drilling a hole cw to the original hole or ccw.

Re: Vibration at 2500 rpm [Re: pjc360] #2368217
09/10/17 11:00 AM
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CW as best as I can visualize (been awhile since I last done it & my note takeing is terrible) & the reluctor rollpin hole is .098" so yes a 3/32 drill bit will work fine. Just be sure to drill outward a bit from the center hole ID & the circular "flat" you are working with is about 5/32" wide so start in the center. A pin punch to start a depression for the bit to start & not wander helps too. You're also on CDT & it is 8AM here so hopefully I caught you in time.


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Re: Vibration at 2500 rpm [Re: RapidRobert] #2368331
09/10/17 02:43 PM
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Originally Posted By RapidRobert
CW as best as I can visualize (been awhile since I last done it & my note takeing is terrible) & the reluctor rollpin hole is .098" so yes a 3/32 drill bit will work fine. Just be sure to drill outward a bit from the center hole ID & the circular "flat" you are working with is about 5/32" wide so start in the center. A pin punch to start a depression for the bit to start & not wander helps too. You're also on CDT & it is 8AM here so hopefully I caught you in time.


Yes I just got the distributor pulled and the reluctor pulled and in the vice and marked where I'm going to drill a new hole.
I'm going cw from original hole and hoping that's what will move the rotor forward lol cause I have no idea.

Re: Vibration at 2500 rpm [Re: pjc360] #2368336
09/10/17 02:56 PM
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Originally Posted By pjc360
I'm going cw from original hole and hoping that's what will move the rotor forward lol cause I have no idea.


If worst comes to worst, you can always drill another hole in the opposite direction and call it good. I'll never tell.


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Re: Vibration at 2500 rpm [Re: pjc360] #2368339
09/10/17 03:01 PM
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Re: Vibration at 2500 rpm [Re: pjc360] #2368344
09/10/17 03:11 PM
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So to dial this in, you would adjust reluctor to be firing Dead center at normal cruise speed with vacuum?

Say 2500-3000 RPM?

Re: Vibration at 2500 rpm [Re: Supercuda] #2368357
09/10/17 03:41 PM
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Originally Posted By Supercuda


Ya but at 35 dollars and waiting a week for the shipping to get from New York to Montana where I am.
I'd rather spend the 10 bucks on a couple of reluctors and drill a new hole myself.

You can see the original hole and where I am going to put a new hole about 15-20 degrees cw of the original hole.

IMG_2634.JPG
Last edited by pjc360; 09/10/17 03:42 PM.
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