Locked timing
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Locked timing
I have a bridgeported 12a that I run in a sand drag rail. i installed a new digital 6al box along with the new motor this spring. I found that the digital box will not talk to the 2nd gen CAS I was using. I subsequently reinstalled a crank trigger set up I previously used.
With locked timing, We started out testing at 26 degrees BTDC. Dropped back in 2 degree incriments and found it appeared to start and idle best at 22 degrees. Took it to the track this past weekend and although it starts good and sounds nasty, it will not rev above 5000 rpm's. We dropped the timing back to 18 degrees and it was a little better but still ran like crap. I am looking to add a timing controller so I can adjust the timing after we start it to find that sweet spot we need to get it to run right.
I am looking at the MSD 8680. Has anyone used it or have other solutions?
https://www.facebook.com/NEORVCA-198...?ref=bookmarks
With locked timing, We started out testing at 26 degrees BTDC. Dropped back in 2 degree incriments and found it appeared to start and idle best at 22 degrees. Took it to the track this past weekend and although it starts good and sounds nasty, it will not rev above 5000 rpm's. We dropped the timing back to 18 degrees and it was a little better but still ran like crap. I am looking to add a timing controller so I can adjust the timing after we start it to find that sweet spot we need to get it to run right.
I am looking at the MSD 8680. Has anyone used it or have other solutions?
https://www.facebook.com/NEORVCA-198...?ref=bookmarks
Are you running efi? If not I'd suggest running a distributor and a 6al wired like this MSD 6A direct fire Ignition for Mazda RX-7 Rotary Engine - Dr. Scott M. Baker simple easy and effective. I personally like using two 6al's one wired to the leading and one for the trailing it will light up anything you throw at it.
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So you are not running a distributor? What are you doing for trailing ignition?
On my bridge port with GSL-SE rotor housings I found that the timing "sweet spot" is 18-22 degrees, when running with zero split. I am running an MSD ignition triggered by one of the pickups in the distributor, firing a FC leading coil (to leading plugs) and one FC trailing coil which goes through the distributor cap to the trailing plugs. No peformance reason why, it was just what I had lying around and it works well enough.
The trailing ABSOLUTELY MUST be run through a distributor unless you have two completely separate ignition systems per rotor.
On my bridge port with GSL-SE rotor housings I found that the timing "sweet spot" is 18-22 degrees, when running with zero split. I am running an MSD ignition triggered by one of the pickups in the distributor, firing a FC leading coil (to leading plugs) and one FC trailing coil which goes through the distributor cap to the trailing plugs. No peformance reason why, it was just what I had lying around and it works well enough.
The trailing ABSOLUTELY MUST be run through a distributor unless you have two completely separate ignition systems per rotor.
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I will warn you, this is not a conventional configuration, but it does work!
The car is 638#. a 135" WB chrome moly tube chassis, center seat dune buggy.
I am running a ported racing beat intake with a 650cfm Holley 4 barrel. (I have a 150hp plate nitrous system , but it is not currently on the car) I set the current SSDRA C-Pro Buggy national record with a stock 12a with the plate system and roughly a 135 hp shot.
The car has a snowmobile clutch drive on it and when tuned, the car idles at just above 3500 rpm's, just into the secondaries. The clutch engages at 4200 rpm's and jumps to 9200 rpm's and stays there the length of the track.
My engine builder (Wankel Works in Natick, Mass) supplied the 2nd gen CAS to use with the old analog MSD 6al box I had. Besides the Bridge-ported motor he also built me a combo peripheral-port / bridge-port 12a that is sitting in the shop waiting for us to debug the BP motor. (apparently he wants to bury the current national record numbers....)
Initially we had it set up so we were firing lead and trail plugs at the same time using 4 coils wired in parallel. It is now set up to run direct fire, lead plugs only. It is much easier to start and tune when not taking the trail into the equation.
When I got the new digital MSD box, I set it up with the two MSD boxes and 4 coils but removed the trail system when the new digital MSD box was giving us trouble.
I hope this background helps.
The car is 638#. a 135" WB chrome moly tube chassis, center seat dune buggy.
I am running a ported racing beat intake with a 650cfm Holley 4 barrel. (I have a 150hp plate nitrous system , but it is not currently on the car) I set the current SSDRA C-Pro Buggy national record with a stock 12a with the plate system and roughly a 135 hp shot.
The car has a snowmobile clutch drive on it and when tuned, the car idles at just above 3500 rpm's, just into the secondaries. The clutch engages at 4200 rpm's and jumps to 9200 rpm's and stays there the length of the track.
My engine builder (Wankel Works in Natick, Mass) supplied the 2nd gen CAS to use with the old analog MSD 6al box I had. Besides the Bridge-ported motor he also built me a combo peripheral-port / bridge-port 12a that is sitting in the shop waiting for us to debug the BP motor. (apparently he wants to bury the current national record numbers....)
Initially we had it set up so we were firing lead and trail plugs at the same time using 4 coils wired in parallel. It is now set up to run direct fire, lead plugs only. It is much easier to start and tune when not taking the trail into the equation.
When I got the new digital MSD box, I set it up with the two MSD boxes and 4 coils but removed the trail system when the new digital MSD box was giving us trouble.
I hope this background helps.
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So I added the 8680 Digital timing controller. The controller allows me to adjust the timing as I am going down the track. Advancing made the motor go flat. Retarding it found the sweet spot at 3-4 degrees from start up timing. I have to put my good carb back on the motor and start tuning the carb in to the motor now. In early testing, the car starts best at 18 degrees advance. When I pull into staging I retard it back to 14 degrees. (I only made two easy passes before parking the car to make more adjustments. I came off the line at 1/2 throttle and didn't lean on it until I found the sweet spot, then it spun right up to 9,600 rpm's and was pulling hard. Ran a 2.42 60', 5.288 300' at 68.66 mph. (300' dirt track)
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