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distributor recurve
https://slantsix.org/forum/viewtopic.php?t=42635		 Page 5 of 6
Author:  Aggressive Ted [ Fri Dec 17, 2010 9:19 am ]
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Quote:
I wonder if cam choice changes this magical 52 degrees number. If cam is installed a degree or two retarded or advanced from optimal, would this change that 52 degree sweet spot?
That is a good question? On my build using the RV10 cam with 4 degrees advance it starts going flat after 54-55 degrees. At 60 degrees it feels like its missing or surging. If you put your foot into it, its fine, but at high vacuum (20 to 25") it surges. So I have pulled it back to 54 total. It would be nice to see how it looks on a dyno and find out what optimum really is.......
Author:  gato [ Fri Dec 17, 2010 9:41 am ]
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as 4 Rock Auto?
i can't recall specifics. i've just heard people gripe-ing in a few groups. wrong parts, lost shipments, late shipments. maybe the same stuff u hear about any mail order business.

i've never heard any body say anything positive about Rock( until, u did today), so i had that sorta preconception in my head. hopefull it will be positive as u say
Author:  oldblue [ Fri Dec 17, 2010 10:51 am ]
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Rock auto is great.Saved $100 over autozoon.
Author:  Reed [ Fri Dec 17, 2010 11:57 am ]
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Hmmm. Now I am worried that I might be overadvancing the timing in my brother's van. I need to plot out the advance curve with and without vacuum advance. :?

I did have one problem with rockauto- I ordered a vacuum advance pod and got the wrong one. It was mispackaged, so it wasn't rockauto's fault, and Rockauto took it back and sent me the right one quickly and painlessly. I order from them fairly regularly since I can order exactly what I want without talking to a counter-jockey who knows nothing and because I often am too busy to go down to the parts store and fight with said counter-jockeys about what I really want to order.
Author:  Aggressive Ted [ Fri Dec 17, 2010 12:54 pm ]
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Reed,

Use the plotting tool in the Engine FAQ that I used for the distributor re-curve.
It makes it much easier to see the effects of the various components and how they effect the over all timing.

There is a blank .xls spreed sheet that you can down load and use or just copy mine and start plugging in the different values. See Joe's Spreadsheet and Instructions for Joe's Spreadsheet or Ted's Curve The values go into page 1 and the second tab shows you the graph visually.

Once the three variables are determined and plotted you know exactly where to make the changes. It's a great tool, enjoy! :D :D :D
Author:  Reed [ Fri Dec 17, 2010 9:04 pm ]
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Thanks! I'l give it a try.
Author:  gato [ Sat Dec 18, 2010 5:10 am ]
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Rock Auto must be something like Amazon.com for auto parts?
i ordered 2 different vacuum pods and a pair of dizzy drive gears. each item is shipping seperately, from different locations. . . . . .. ?
Author:  Sam Powell [ Sun Dec 19, 2010 6:36 am ]
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Quote:
Sam- could you elaborate on how I change the slot in the vacuum can arm? I can see no slot and no way to disassemble the vacuum can without destroying it.

I don't know about the 52 degrees either. I have heard numerous knowledgeable people say the slant likes 32 degrees of mechanical plus base advance total, and the rest is just gravy from the vacuum pod. Since this van is a hauler, I'm going to be a bit conservative in the total advance to avoid over-advancing the timing and bogging the motor down.

I know that right now the van does OK and it has essentially a non-functioning vacuum advance.

P.S. I have also had nothing but good experiences with RockAuto.
Sorry, I have been away from this thread. The slot you can change is on the arm outside the pod. Just lengthen it to increase the movement. There is a sheet metal frame part that the arm moves through, and the narrow part of the advancing arm is in the slot. If you lengthen that slot it will move more.

Sam
Author:  Reed [ Sun Dec 19, 2010 8:26 am ]
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OK- I think I get what you are saying.
Author:  matv91 [ Tue Dec 21, 2010 3:42 am ]
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Did some in park no load testing on my stock motor at 2000 rpm the sweet spot was 44 degrees Below 44 rpm and vacuum drop Above that vacuum and rpm stay steady . Till about 48 degrees .AT this point exhaust sound changes and motor starts running rough.AT 52 and more rpm begins to drop. Is this a good tuning method
Author:  Aggressive Ted [ Tue Dec 21, 2010 10:56 am ]
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When I quoted my numbers and built the graph listed in the Engine FAQ, it was for my "torque and mileage" build.......not a stock motor. So with the increased compression, taller cam, porting, etc.....it can take the advance and run super smooth from 600 rpm on up to 4500 rpm.
Author:  Force Fed Mopar [ Sun Dec 26, 2010 6:54 am ]
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Lotta good info in here. You what would be nice, if if we made a list of what distributor setups worked w/ what combos. Like, a thread where you just post your engine build and the distributor curve you found works best with it. Might help people get a good baseline if they can look at it and say "That engine is very similar to mine, let me set my dizzy up like that and see how it works". W/o having to search through pages and pages of discussion and explanations :D
Author:  oldblue [ Sun Dec 26, 2010 8:57 am ]
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Good idea.Vehicle weight,trans,gearing and use as parameters.After that the compression,carb and camshaft.Just my two cents.
Author:  Aggressive Ted [ Sun Dec 26, 2010 10:43 am ]
Post subject: 
Quote:
You what would be nice, if if we made a list of what distributor setups worked w/ what combos. Like, a thread where you just post your engine build and the distributor curve you found works best with it.
Gents,

That was the thought I had as well, to consolidate all the info in the Engine FAQ - Recurve thread and Engine Build Matrix. Thanks to Doc, Ceej and others we have the threads.

Joe's spread sheet really helps to visualize what is happening when you start documenting your curve and when it happens. Using it saves a lot of time and creates a great baseline for the recurve. I asked to have my recurve plot sheet posted as a baseline using Doc's build guidelines for the "Torque and Mileage" engine build.
Author:  gato [ Wed Dec 29, 2010 9:22 pm ]
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ok guys. here's what i got so far.

having 3 dizzies to play with, i have saved some $$$ by swapping parts. i took the heaviest springs and the lightest springs and set up 2 dizzy's. one i set up my Pertronix ignitor, the other, the points set up.
Rock Auto delivered, just as u folks said they would. they messed up one detail, but that showed up today.
i received a VC-173, a VC-239 and 2 drive gears.
the VC-173 is marked as 6.5R
the VC-239 is marked as 8.5R

i drilled the point plate to accept the later style vacuum pod with the hooked actuator arm. i also needed to modify the base plate for the Ignitor for clearence for the VC-239 hole.

i have not done this as scientifically as so many of u have. as yet, i have not make a chart of what is happening.

the VC-173 has an 11.5R governor, and the points.
the VC-239 has a 13R governor, and the Ignitor.

i put the Ignitor back in the A108 2 days ago. did some tweekin' last nite. took it to work 2day.

i have the timing mark set at just about 7* BTDC. plus the 13R = 30* initial and mechanical. add in the 8.5R of the VC239 and i'm up to 47*. so far, i have all the same performance i had b4 the old dizzy failed, with none of the ping. there is a bit of a sense of "stumbling" that i feel between 1500 rpm's and 2300. i have yet to play with adjusting the VC .
i may try bumping the initial time up to see where the pinging starts.
what puzzles me is the idle speed. where it is now, it idles at about 850. the idle stop screw is backed all the way out. i can't slow it down anymore. if i bump the initial up, the idle speed goes up. what am i missing? how do i slow it down to normal? or is the idle speed of a super six supposed to be higher than the 1V?


as a foot note. . . .

the old non-adjustable VC that failed was marked 12R. it had an 11.5R governor. i was running it at between 5-7 initial. that would put my total at 52-54*. i guess that is why it was pinging?
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