Carbs...Idle...Timing....Am I missing something??

[kirkland]

1991 70hp Rude.....<br /><br />All three carbs rebuilt with Bomb kits...Link and sync done by the book....upon checking idle timing found it to be 3d BTDC..book says it should be 3-5d ATDC...with that said the book also suggests i start the Low Speed Mixture Screw 1 turn out from full in...with the timing at 3d BTDC and SS screw at 1 turn out it idles fine but smokes alot...i'm running 100:1 in tank as well as VRO...usually do this for first tank on season...fresh gas and fresh oil....new tach installed and it's idling in gear in tank around 900 RPM now the water level is about five inches lower than if is was in lake.....with all of that said if i advance the idel timing to around 4d ATDC won't that increase the RPM's....the book tells me if the PRM's are too high to check "Induction System" for air leaks and repair as needed......how should i check this if indeed the timing advances the idle RPM...book tells me between 700-800 idleing in gear....hope you followed my rambling here.....<br /><br />Thanks in advance

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

To be honest we dont worry at all about the actual degree number at idle. Boats that sit low will be different than those that dont. What ever it takes to ide at 650 in gear in the water. <br /><br />As for the smoking that may have something to do with the brand of oil and the spark plugs.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

Using X25 and Champion QL77JC4 gap .30

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

We're sure you mean .030 but good choices!

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

Dhadley,<br /><br />First thanks for the help, it's much appreciated<br /><br />I was incorrect about the idle RPM's should be between 600-700 in gear like you said 650. Now that would lead me to believe that i need to retard the timing even further...do i have a air leak as the book leads me to believe if the RPM's are high.. <br /><br />Should i set the idle timing by the book (3-5d ATDC)and then search for air leak. or should i just retard the timing even more than it is right now.??? is >4d BTDC a indication of another issue??<br /><br />To clarify the Oil is E/J X25 bought new last week..two days later i saw the new X30...any big difference...X25 been around a long time if my memory is correct...<br /><br />Thanks Jeff

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

yes i meant .030 ...fat finger s and all...

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

If youre at 3* before now, and go towards 3* after -- that will be retarding the timing.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

Oh.......i thought advanceing the timing would move the timing toward ATDC and retarding would move toward BTDC...my bad...see you learn something every day..

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

I know what you mean. <br /><br />Before and after top dead center refers to piston position basicaly. If its at 3* now, to retard it would move it to 2*, 1* or 0 (TDC). To retard it further you'd have to fire the plug after the the piston is at TDC (ATDC).<br /><br />It can be confusing thats for sure.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

Another quick question...manual says use a shop tach...is the tach i just installed not accurate enough to do these adjustments ????... this and proper prop/hieght setup is the big reason for drilling the 3 1/2 inch hole in dash....any thought would be helpful...<br /><br />Also i guess i was thinking that timing advance was moving + not - ...manual talks about maximum spark advance and gives 18-20 ATDC i just assumed the moving toward ATDC was advanceing the timing.

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

Max timing should be BTDC. And it'll be a very specific number. Like 19* for that motor.<br /><br />If your new tach is a BRP or an OMC, thats fine.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

got ya.......i must need to get some sleep...was up all night at a structure fire and it has caught up to me i see.....you again point out that i'm quoting the wrong info here it is indeed 18-20* BTDC ...man i think i'll take a break for a little while before working on this thing agin....i need to read and then re-read this manual so i know i'm doing this correct ...how i got that backwards i don't know...again thanks.. <br /><br />Also the Tach is a "TeleFlex Amega Pro"

 

[ob15]

Re: Carbs...Idle...Timing....Am I missing something??

Don't want to change the subject, but DEIFan, where abouts in the Finger Lakes do you live? I grew up in Union Springs. Getting ready for bass season next month?

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

Lol! Sleep would be good!<br /><br />Dont set the timing at 20*. Youll get an unwanted surprise. 19* is plenty. <br /><br />You may want to, at some point, check the t-flex tach aginst an OMC or BRP just to make sure.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

I Live in dryden near ithaca

 

[ob15]

Re: Carbs...Idle...Timing....Am I missing something??

Been there many times. Back in my high school days it was a big football & wrestling rivalry.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

I like the area alot...many people think of NY and have no idea what this area is like.....God's country.....rural and clean...good place to raise kids...

 

[ob15]

Re: Carbs...Idle...Timing....Am I missing something??

Ain't that the truth. My folks live right on Cayuga Lake and I can honestly say the I have never seen a sunset as nice as the ones up there.<br /><br />BTW go Mikey (#15).<br /><br />Good luck getting the motor tweaked up.

 

[kirkland]

Re: Carbs...Idle...Timing....Am I missing something??

DaveF,<br /><br />Yeah I'm a big 23 fan myself....And this area is one of the best palces on earth i could think of living....lived all over and been to all lower 48 a least twice..(Navy Brat).. But you have to be able to come to grips with winter ..if you like snow and cold ya got it made...<br /><br /><br />Dhadley,<br /><br />Quick Question..My manual said nothing about doing anything with the (Freeze Plugs maybe) round concaved disks in my rebuild kit ..should i have changed them and would this cause an air leak if i didn't....Carbs were soaked overnight when rebuilt.??

 

[Dhadley]

Re: Carbs...Idle...Timing....Am I missing something??

You gotta be real careful when taking them out. If you punch thru them you can damage the carb body pretty easy. I'd just put the sealer back on them and let it go.