Can I just run this by you folks here? I am trying to understand distributor curves, and according to my manual, my 1967 slant 6 engine should have a initial timing of 5 BTDC, a mechanical advance total up to 25 BTDC, and a vacuum advance up to 15, for a total of 45 BTDC max with all three combined. That seems consistent with the information I have found here on the site and around the internet, although I know some people go with higher initial timing and less mechanical. They still seem to come out totalling around 45 BTDC max in the end.

What I was wondering is if my curve could look like this and work well:
500 rpm = 5 BTDC initial, no mechanical yet
1500 rpm = 15 BTDC (initial and mech)
2000 rpm = 20 BTDC (initial and mech)
2500 rpm = 25 BTDC (initial and mech)
3000 rpm = 30 BTDC (initial and mech)
3500 rpm = still at 30 because it tops out without vacuum at 30 BTDC.

Does that make sense? Its nice and clean, but it doesnt match the curve in the manual, which advances timing very quickly from 750 rpm to about 2200 rpm and then starts levelling out. It still stops at 30 BTDC with the initial and the mechanical and without the vacuum advance though. Thoughts? Input? Advice? Ideas?

Read this thread:

http://www.slantsix.org/forum/viewtopic.php?t=13264

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

Wow, thats a lot of information. Ok, so what I summarize from reading that (and correct me if I am off base) is that the best timing for a slant 6 is a higher than stock initial timing like 10 or 12, less mechanical advance but still the amount to get it to around 30 to 32 (so a mechanical of 20 or so) and then vacuum for another 15 to get it to the ideal total of 45-46. Got it.

But, if I am going to keep the stock service manual timing of 5 BTDC, then I am looking at 25 mechanical, and 15 vacuum, which again gets me to the ideal total timing of 45, Slightly different routes to the same destination in the end.

Adjusting the curve would be easier with a distributor machine. Does any still have a distributor machine? This would be so much easier with a distributor machine, and I have called 30 + shops trying to find one only to hear "we got rid of that about 5 years ago" over and over again. I mean, San Bernardino is where Route 66 ends, and they have a four day car show, and no one has a distributor machine???

Up here DI & I seem to be the only ones that have such a machine.


Richard

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Part of Tyrde-Browne Racing

Do you have any experience with different curves on the slant six engine? Man, I wish I had a distributor machine to try out different timing curves on.

Just what I did on both of my cars (slant powered 53 Ford & 63 Dart), would love to run them on an eddie brake dyno. That would let me see what kind of curve they really need.


Richard

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Part of Tyrde-Browne Racing

Do you know what your current curve is at different RPM's? Id be interested it seeing how it matches up to the one above.

After Redding I'll pull dist and check.

Richard

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Part of Tyrde-Browne Racing

Thanks. I was wondering where to get springs to change the curve. It looks like some people on the forum make/sell them?

Send a pm to bigslant6fan. He has the spring kits.
Also, the later SL6 with the 2-bbl super six setup, had 12° static initial timing, 18° added mechanical advance, and app. 18° vacuum advance from the factory.
Some links that may be interesting:
A different Distributor Springs question
I modified my distributor for easy recurve tests.

Olaf.

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Aspenized

Take a look at my curve in the Recurve section of the Engine FAQ. It is fairly aggressive which makes the engine feel very punchy or snappy. Use the plot sheet to map yours. Then you can easily track changes.

It all depends what type of vehicle you have and how you might change it's response. Some stock SL6 cars and trucks feel very flat or not very punchy to me. I am biased since my other two cars are Hypo 440's. I like that type of feel or throttle response.

I have run several curves from super light springs to very heavy and various initial timing settings and various vacuum advance pods and pod settings. I have a 74 Dart Swinger that is heavy with 2.76 gears in a 8 3/4 w/Sure-Grip. I have set it up for best feel (spunk) and mileage for the twisty foothills I travel daily. It feels very good and is a lot of fun to drive.

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG