formula31

Stick with the tb-4. Set the timing at 4000 rpm to 34 degrees btdc. Ive seen a lot of these modules not do 24 degrees like they say. You will need a timing light that can do the advance. If you feel you must go aftermarket, the crane hi-6 is my choice but you will see no benefit other than a cleaner idle if your carb isnt set right. The 750 cfm carb will be fine for that engine up to about 5400 rpm.

Corbs

K24u, I had basically the same set-up in my 1991 25' Checkmate, but with a 365 Magnum. I called the Merc Tech on the Ignition and was able to find out about the rev limiter by giving them my engine serial number - no rev limiter on mine. My motor with a little more compression, Oval Port heads, Comp Cam, RPM Air-Gap, 830 Holley and IMCO Exhaust gained 500 RPM at WOT (went from 4900 to 5400 RPM). I balanced and blueprinted the original 23 Mirage and picked up about 7-8 mph - ran 72.2 on GPS. I'm having a larger motor put together and want to sell some of my 454 parts. I still have the Oval Port RPM Air-Gap if you're interested. Send me an email. Thanks

GOODT

off subject but as a seadoo cert tech have to ask,.... whats with the rotax 454 screen name....

and yes its the only 2 stroke that I play with, so if you have an out board 2str Ill still recommend someone else to work on it,, sorry Im old school....you specialize in something be the best you can be at it and then referrer other to someone that specializes in that product

k24u

I'm going to put the boat in do the timing thing and see how it runs with the 24 bravo 1 compared to the week-end and do a plug check, then I'll change and put the 23 mirage on and try it. I would think I would pick up some rpm with the mirage i post later

k24u

Well if it ever stops raining I will see what happens but I have changed the intake manifold from a performer to a performer rpm air-gap and I have set the timing at 10degrees @ 3800rpm so i am just waiting on the weather

SB

iTrader: (1)

It will run like a turd if this is true and not a typo.

Total timing is usually between 34 and 38 degrees on a N/A BBC. That 10 # is probably your base timing # (at idle).... Total is what we are interested in since the module is fixed.

formula31

Yea, I hope thats a typo, 10 degrees at 3800 will not work well. 10 at idle and a 24 degree advance module will give you 34 at 3800 but you should check it. I always set mine at 34 at 4000 and let the idle land where it will, the modules are not all that exact.

MOP

Post which Tbolt pack you have, I have the chart for where Top Time comes in it varies from pack to pack, some can be set as low as 2000RPM like my HP24 most others are set at a lot higher RPM. Idle timing don't count for crap correct Top Time is the most important!

Phil

k24u

v8-24-2k22a i have set the timing at 10degrees advance a idle

Shallow Minded

k24u,
Any updates? I've experienced a similar problem with my set-up. I've got the MSD ignition, but am similar otherwise. Curious to hear what you figure out.