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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 Topic: Sanity Check My Tuning
    Posted: Jul/22/2017 at 1:17am
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 1:22am
1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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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 12:42pm
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" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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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 12:36pm
I emailed you, Chris.
1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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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 11:28am
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 11:37am
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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 11:13am
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 Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2017 at 10:35am
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" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 10:05pm
Well, since the exhaust just dumps after the mufflers, I'm gonna have to shimmy under the back end to be unscientific. And to be scientific, I haven't dropped the money on an o2 sensor, sender, and gauge, but I sure wish I had. I have a bung in the exhaust still from when I was running EFI.
1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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Post Options Post Options   Thanks (0) Thanks(0)   Quote needafasterAMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/18/2017 at 9:47pm
It all looks fairly good, the only thing I did not see is the quick un-scientific exhaust test.
Does your eyes and noise burn when you stick your face in the exhaust when it is running.
Or the scientific way with a O2 sensor. the only way to go to get the best fuel mileage.

The two quick fuel carbs that I had /have on my car where way Fat.
74 AMX, 401
Viper spec T56 6 speed trans
Hydroboost brakes with rear disks from a Avenger
3:73 TG rear,now Trutrac with 3:15
A Turbo is in my future.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 2:32pm
You might want to just take a chunk of rubber, say a kid's eraser, that fits over the pin on the vac advance can. You can make something fancier if you like later, but that is a cheap way to try it out. Make a couple with different levels of restriction and see what it likes.

Thanks!

Chris
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Red20 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/17/2017 at 11:56am
I'll let you know what mileage looks like when I get through a full tank.

I need to make a stop plate to limit the vacuum advance total. I'm not getting any discernible detonation, but I can feel when it's going too advanced and lugging a little. There's definitely a point of diminishing returns with ignition advance. I think I'm going to shoot for 10* total vacuum advance and see how that feels. Without a dyno, it's all by feel, but I'm pretty in tune with AMC 360s these days.
1969 Javelin SST "Screamin' Banana" - 16k original miles, warm 360, TH-350, Model 20 TracLok, DAILY DRIVER
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