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Sanity Check My Tuning

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Red20 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 9:35am
I made a vacuum advance stop plate for my MSD billet distributor. It was advancing 18* (advertised 16*) and I'd really prefer about 10*.



BUT...I mismeasured when I trimmed the stop tab (see yellow arrow) and it now advances 17*. I just shook my head and went inside. I'll make another one later today. I'm pleased with the design though.
1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018
1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bandana Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 10:13am
Interesting modification. Never really looked how the vacuum advance works on these. I also seem to be getting too much advance from my billet and have disconnected it for now to keep from pinging. When you get yours set to limit the advance to 10 degrees can you post more detail on it? I assume you need a longer tab on the stop?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 10:28am
You could try a set up like this. Easier to adjust but the same effect.

My edit is that there is no way to upload an image!!!!!!!!!!! If you want a picture of something similar to what you have that is adjustable and basically free, please PM me.

Thanks!

Chris

PS: Yes, I have done the image upload and post many times, it is not working now.



Edited by ccowx - Jul/21/2017 at 10:37am
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Red20 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 11:36am
I emailed you, Chris.
1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018
1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER
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Red20 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 11:42am
Originally posted by Bandana Bandana wrote:

Interesting modification. Never really looked how the vacuum advance works on these. I also seem to be getting too much advance from my billet and have disconnected it for now to keep from pinging. When you get yours set to limit the advance to 10 degrees can you post more detail on it? I assume you need a longer tab on the stop?


I'll take a few more pictures when I pull it off in a bit. I'm anxious to see what ccowx's solution entails. Adjustability is certainly good.

As for the piece I made, it's just a piece of aluminum I cut on a scroll saw with a fine tooth wood blade. I mocked it up first in cardboard from the end flap of a 12 pack box. Probably took me 15 minutes. The rear screw for the canister is pretty short, so I counter sunk it a hair with a forstner bit. I like aluminum because if you're not going for fine finish work, a lot of wood tools will cut it just fine.
1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018
1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER
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Red20 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/22/2017 at 12:17am
I've got it about as close as I can get to my 10* vacuum advance goal now. I made another plate and ended up 6* advance. Just the slightest touch up on the grinder and I was at 9.5*. I used my vacuum pump to ensure it travelled smoothly through the range and after a slight tweak had it good. The vacuum advance starts at about 6 in.hg and is all in by 11 in.hg. Initial is 14* mechanical plus 9.5* vacuum for 23.5* at 750 RPM idle. I'm pleased with that for now, but I haven't taken a test drive just yet. I'll probably run over to a cars and coffee cruise in tomorrow morning and see how she does.

Here's the first attempt and the second side by side.


Here it is in the distributor. The stop arm was bowed up here from the way I wedged it into place causing the breaker plate to bind up slightly. I straightened it all out on final fitment.


Here's the scroll saw I cut the aluminum with. My bandsaw cuts a lot more smoothly, but I didn't have a blade on it and this was quick and ready to go.



Edited by Red20 - Jul/22/2017 at 12:22am
1969 Javelin SST "Screamin' Banana" - Totaled Feb 2018
1973 Hornet Sportabout X "yellajack" - 360/727/TracLoc DAILY DRIVER
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