[Thunder90]

I am doing an engine upgrade on my 2005 Thunder Mountain Custom. It came with the 95 inch kit already, flat-top pistons, SE203 cams, stock heads. I'm having the heads ported/flowed and he's also going to deck the heads to bump up CR north of 10:1. I'll be installing a set of S&S gear drive cams (probably 570s)......and it's a carbureated motor.

I bought the Crane HI-4TC adjustable ignition module as well.

Question is: what should the initial and advance settings be (given that I'm bumping up compression and going with the bigger cams)? I plan on having my local shop dyno-tune it where they will adjust the ignition timing to get it to run at it's best......but what should I set the initial settings to after completing the build (using the dial knobs on the module itself) while breaking in the motor?

 

[kblb]

hi-4tc

I would leave all settings on zero set your advanced slope to 2,3,or 4 if it pings at this setting put your initial timing to -1 or -2 this should get you by until you do the dino.

 

[Otto]

curve 5 with 5 initaul is as close as stock and a good starting point

 

[Seahag]

I am doing an engine upgrade on my 2005 Thunder Mountain Custom. It came with the 95 inch kit already, flat-top pistons, SE203 cams, stock heads. I'm having the heads ported/flowed and he's also going to deck the heads to bump up CR north of 10:1. I'll be installing a set of S&S gear drive cams (probably 570s)......and it's a carbureated motor.

I bought the Crane HI-4TC adjustable ignition module as well.

Question is: what should the initial and advance settings be (given that I'm bumping up compression and going with the bigger cams)? I plan on having my local shop dyno-tune it where they will adjust the ignition timing to get it to run at it's best......but what should I set the initial settings to after completing the build (using the dial knobs on the module itself) while breaking in the motor?

You say you are bumping compression up above 10 to 1....well how far? The crane canned maps are very agressive down low in the rpm band. For a long time, I tried to stay close to that 5 initial...usually running -1/-2 initial and an advance of 3/4...but whenever it got above 80* ambient outside, I had pinging problems. Daytona Twin Tec recommends no more than 30* advance at 5000 rpm for motors with 10.5 compression; which is what I run. I finally struck on a combination that works well for my build without pinging...and I hope to get it on a dyno this spring and see if it shows on the dyno.

The settings I came up with for 10.5 compression, is -5 initial timing with a curve of 6. This way you are starting out lower, for the lower rpm ping zone of 2500-3500 rpm...but because the advance curve is more agressive, it catches back up as the r's climb (These settings put the advance right at 30* at and above 5000rpm as DTT recommends). If you're not going as high as 10.5, I'd suggest starting at -2 or -3 initial atleast for starters with a curve in the 4-5 range.

 

[Seahag]

If you want to compare the various curves, go to the page I'm linking to, scroll down to the bottom and download the PClink software. It is a read only version where you can see the preprogrammed maps that come with the Hi4TC.

http://www.cranecams.com/index.php?show=browseParts&lvl=4&prt=2072