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11-19-2019, 10:19 PM | #1 |
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Join Date: Aug 2010
Location: McMinnville, TN
Posts: 2,327
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Point bounce RPM
My Sun machine set a record today with a distributor. A customer sent in a distributor and he had previously purchased the parts elsewhere (Mac Van Pelt). I installed his supplied points, bushings, rotor, etc. This was a typical 1937-40 68 series distributor.
I had previously run three other distributors tonight, with most having the points start to bounce at around 5300-5850 rpm's. This one ran all the way up to 7870 RPM's before the points started to bounce. While a flathead will never see those RPM numbers, that is a record for me. Hats off to Mac Van Pelt for selling quality points! They appeared to be the same points I have used but this set exceeded the norm.. Many "larger" vendors are selling crap points that make setting the dwell a nightmare if even possible and can rarely exceed 2600 rpm's before point bounce starts. |
11-19-2019, 10:25 PM | #2 |
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Location: Shelton, WA
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Re: Point bounce RPM
I commonly get > 5000 with NOS Ford points on my Sun machine. I usually back off as that is unreasonable territory for most flatheads, valves will float before then on stockers. I commonly take my avatar to 5500 when pulling onto the freeway. On that car I have 200 lbs pressure going over the nose of the cam.
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11-19-2019, 10:31 PM | #3 |
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Join Date: Aug 2010
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Re: Point bounce RPM
Yes, I agree, I do however out of curiosity run all of them to the point of seeing what they will actual handle. Our results differ, is the MOST I have ever gotten from a NOS set is 4400 rpm's (crank). The newer quality points seem to have quite a bit more spring tension thus likely why they will handle more RPM's, however I am also aware that too much spring tension will cause the rubbing block to wear much sooner.
Regardless it is all irrelevant as 99% of the flatheads out there will never see these rpm's |
11-20-2019, 08:46 AM | #4 |
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Join Date: Jan 2011
Location: Central Ohio
Posts: 5,067
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Re: Point bounce RPM
Nice new record Mike . . . thanks Mac for good quality points! Most of the ignitions I tend to screw with have magneto points - so they tend to spin up pretty damn high.
This is one situation where "More is Better'! LOL |
11-20-2019, 10:05 AM | #5 |
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Location: Ashland KY
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Re: Point bounce RPM
What’s the solution to prevent bounce???? Increase spring tension???
__________________
DON P |
11-20-2019, 10:21 AM | #6 |
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Re: Point bounce RPM
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11-20-2019, 11:22 AM | #7 |
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Location: Central Ohio
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Re: Point bounce RPM
Spring tension is one factor, the other is the type/characteristics of the actual distributor cam. Many performance distributors/magnetos use more of a "ramp" to lift the points, than a super-sharp peak. Makes sense that the ramp is less susceptible to causing point float.
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11-20-2019, 11:31 AM | #8 |
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Join Date: Aug 2010
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Re: Point bounce RPM
Bored,
That is correct, however I can only speak in context to original Ford designs. The Lincoln V-12's have a much more subtle cam design with a more rounded cam lobe. |
11-20-2019, 01:28 PM | #9 |
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Location: Socal
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Re: Point bounce RPM
What are these "points" you speak of?
These are the only points I'll put in a distributor.... |
11-20-2019, 09:29 PM | #10 |
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Join Date: Oct 2019
Location: Carthage , Tennessee
Posts: 199
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Re: Point bounce RPM
Michael,
I didn’t know you had a distributor tester too. That is good to know,,,,I have some work for you. Tommy |
11-21-2019, 11:24 AM | #11 |
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Location: Chester Vt
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Re: Point bounce RPM
The SBC dist dist is good for 6500. Works well on 6 volts, set it forget it. The stock crab worked well on the stock car up to 5K
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11-21-2019, 06:34 PM | #12 |
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Location: SPEEDWAY INDIANA
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Re: Point bounce RPM
I set them all at 2500 to 5000....lube well and let them run for a few minutes at 5,000 .plus.
Also soak every fiber block in marvel mystery oil , found out years ago that will extend the life of the point a ton......(and i like the smell))) Last edited by BUBBAS IGNITION; 11-22-2019 at 11:15 AM. |
11-21-2019, 07:18 PM | #13 |
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Re: Point bounce RPM
Jim,
Welcome back!! |
11-22-2019, 11:17 AM | #14 |
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Join Date: May 2010
Location: SPEEDWAY INDIANA
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Re: Point bounce RPM
Thanks Mike i just edited the post , must have been on the drugs when i wrote that one.
Glad to be back home after 10 days in hosipital......getting back (again) , slow but sure i guess... |
11-22-2019, 12:22 PM | #15 |
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Join Date: May 2010
Location: Indianapolis
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Re: Point bounce RPM
I did not know you were in the hospital. Good to hear that your out. I need to stop by the shop and give you and Terry a hand soon.
I have been so dammed busy at home I think I need to step back and approach from another angle. |
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