It looks like I need to replace my Thunderbolt V ignition due to the built in rev limiter. It shuts me out after hitting 4900 rpm. I can go with another Thunderbolt system, version IV or an after market unit. I was looking at a Crane system witch has an ajustable rev limiter and a variable curve slection. Another bennifit of the Crane is that I can use my existing distributor. So... give me your thoughts, I would like to make a decision early this week.

THX
Sam

I am dealing with the same dilemma as you. Your rev limiter should be kicking in at 5050 rpm. Check your tach against another one or a test meter. You may already be at 5050 rpm. I have supercharged my motor and would like to spin it to 5300 but cannot with the Thunderbolt Five. It also has a knock sensor which I feel is a good thing to have. I am researching replacing the stock module with one from a hp500. I called Mercury Racing and they said it should work just that the curve would be different and it does move limiter to 5300. All I need to do is get to my boat and pull old module out for comparison. I will post here if my attempt is successful.

Dave

Sam, Good to hear you got your boat back, I have heard good things about the Crane system, but have no actual experience with the add on set up your looking at.

Bigwavz, I supercharged a 1997 454Mag carb with T-Bolt V and Knock sensor and I used a Merc 525sc ignition module and it worked great.
By the way I still have the 525sc module if you are interested.

Lee, would that module let me get around the rev limiter that I currently have.

Sam

Sam, It would not work too good in a non supercharged application because of the limited amount of advance in the module.

I just installed two of the Crane 7Ms on my Cig - I had absolutely no problems. You'll need someplace to mount them, and you'll need to modify your distributors, but they work great. If you have any questions let me know..

Actually I am going to change out the TB V for a IV this week. Thanks for the reply Lee.

Sam