Sanity Check My Tuning

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

I emailed you, Chris.

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?

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.

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