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WakeWorld Discussion Board » >> Boats, Accessories & Tow Vehicles Archive » Archive through January 14, 2005 » timing question « Previous Next »
By alan plotz (alanp) on Friday, September 17, 2004 - 8:47 pm:    Edit Post Delete Post
i talked with a mastercraft mechanic and he said to time the boat to +15 tdc. does this sound normal? i did and i didnt have any problems. i have since retarded it to +8 tdc. since then i have had backfiring problems in the carb only when i am starting the boat. once its warmed up i have no problems at all. my friend who is a heck of alot more knowledgeable than me at this stuff thinks i need to retard it back to 7 or 6 and this could perhaps stop the problem. any thoughts
 
By 882001 (882001) on Saturday, September 18, 2004 - 6:16 am:    Edit Post Delete Post
28-30 btdc at full advance 2500 rpm+
 
By michale detillion (michale) on Monday, September 20, 2004 - 11:00 am:    Edit Post Delete Post
maybe i am missing something here.You say"i talked with a mastercraft mechanic and he said to time the boat to +15 tdc.i did and i didnt have any problems".then why did you change it?.put it back to where the mastercraft mech. told you to put it.do not listen to your friend.listen to your mechanic.
 
By Rod McInnis (rodmcinnis) on Tuesday, September 21, 2004 - 11:38 am:    Edit Post Delete Post
It is impossible to give an accurate answer without knowing specific information about the motor.

It is entirely possible that your Mastercraft Mechanic was familiar with the year and model of the engine and can answer that question off the top of his head. I would be skeptical of any answer from any "friend" or internet source unless they were referencing some engine manual on an engine just like yours.

The big unknown is the advance curve of the distributer. More modern fully electronic ignition systems control the timing from the main computer, and you generally don't have any adjustments to make. The more traditional distributor approach has an advance system that can be based on venturi vaccuum, centrifugal weights (in the distributor) or a combination of the two.

What is really important is the total advance, i.e., where the timing ends up when you have reached higher RPMS. As 882001 said, 28-30 is a fairly typical number. What that equates to at idle speed is a function of the advance curve of the distributor.

And I second the question from Michale: If the Mastercraft mechanic told you 15 btdc, and it worked well, why did you change it?

 
By alan plotz (alanp) on Thursday, September 23, 2004 - 9:22 pm:    Edit Post Delete Post
well it was changed per the recommendation of a friend that i respect and has alot more knowledge than myself. we both thought it was a little wierd to have the timing advanced so far. i think ill try set the timing at 28-30 at 2500+ rpm. thanks for the advice.
 
By michale detillion (michale) on Friday, September 24, 2004 - 11:03 am:    Edit Post Delete Post
once again i must be missing something.if it ran fine and your mecha

never mind .you will figure it out someday.

 
By Psyclone (cyclonecj) on Friday, September 24, 2004 - 11:04 pm:    Edit Post Delete Post
Set it to 10 deg static at idle and go wakeboarding
 
By Dan (texastbird) on Saturday, September 25, 2004 - 5:45 pm:    Edit Post Delete Post
7 deg of timing whouldn't make it backfire through the carb. These problems sound unrelated.

15 deg base timing sounds like a lot to me. I agree with Psyclone - 10 deg BTDC is about right.

I would not suggest trying to set your timing at 2500 rpm. The timing will advance with rpm on it's own once you set base timing (at idle).

(Message edited by texastbird on September 25, 2004)

 
By alan plotz (alanp) on Monday, September 27, 2004 - 7:33 pm:    Edit Post Delete Post
hey thanks for the input. ill get it sorted out. i was really just trying to get a feel for the normalcy of the 15 setting. i didnt want to apply a bandaid(by setting it at 15) just because it worked, if there is indeed a larger problem going on here.
but nevermind that michale, youll figure that out one day. please if berating someone is what youre into please just go into a chat room with some other 15 year olds and have at it.

 
By michale detillion (michale) on Tuesday, September 28, 2004 - 6:00 am:    Edit Post Delete Post
Alan,first off I am a little older then 15.what I posted was not meant to "berate" you.if your 1995 mastercraft prostar has the 275 h.p. Indmar TBI [GM 5.7L] then your mechanic gave you good and correct advice.If your one of the lucky few that picked up a 1995 Mastercraft with the 320 h.p. corvette EFI then your timing should be set at 12 deg.btdc.Most mechanics {not all} know what they are talking about when it comes to tune ups.That is the first thing they learn.I couldn't understand your hesitation on taking your mechanics advice.Let me help to put your mind at ease.My 20 ft Cole with a 454 is set to 22 deg.btdc.My Ski Natique with a MSD ignition it set to 17 deg. btdc My Calabria with a 350 is set to 12 deg. btdc.It is not that uncommon with the pour quality of today's fuel to see timing #s that high.I still find the best way to set my timing is by the seat of my pants and listening for pinging.Then I check it with a timing light just out of curiosity.Oh and by the way you are applying a Band-Aid.To fix the problem of the bad gas that the government and oil companies are forcing us to use.
Sorry for the novel and if you took my last post the wrong way.........m.

 
By alan plotz (alanp) on Tuesday, September 28, 2004 - 8:01 pm:    Edit Post Delete Post
thanks for the reply. well i got a second opinion and this guy said to set the timing at 10. i dont have a mechanic per se, i had just made a call to a guy that works for a mastercraft dealer about the timing. anyway. no harm no foul.
 
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