boggs out/spark advance?

laker925

Petty Officer 3rd Class
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Jun 10, 2005
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85
I have a 74 mec 85hp(ser#3743683) outboard that starts to bogg out as I go into forward gear(and the shifter seems a bit tight).Just had the carbs rebuilt and fuel lines/pump replaced.Is the spark advance out of range since once in a while I can shift fast and it will not die out ,but 95% of the time it boggs out as I go forward.The reverse does fine.And the idle is a tad on the low end.<br />What may it be and would I need to adjust the cable along with the advance screw(in or out?)<br />Any help is appreciated
 

Barnacle_Bill

Admiral
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Feb 8, 2004
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6,469
Re: boggs out/spark advance?

You may just need a link and sync. But you need a manual to do it properly.
 

timmathis

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Apr 24, 2005
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1,295
Re: boggs out/spark advance?

Read post on linc&sync by Clams Canino. He tells you how to get that hole shot going.
 

Chris1956

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Mar 25, 2004
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28,074
Re: boggs out/spark advance?

Laker, I have always found that it was necessary to shift into forward quickly and immediately advance the throttle to fast idle, to keep them from stalling. The carb idle setting must be rich enough to allow the motor to accelerate smoothly and lean enough to allow the idle to be smooth. This compromise is hard to get correct.<br /><br />If after idling for a moment, the motor will not rev up, it is likely your idle mixture needs to be richer. Since this will make the idle rougher, you need to find that compromise.
 

laker925

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85
Re: boggs out/spark advance?

where do I go to get that link and synk info?
 

laker925

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Jun 10, 2005
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Re: boggs out/spark advance?

I also ment to add that a new timing belt was installed also so I hope that is not a factor since I got the pointed aimed right and it fires right up.<br />The rebuilder said the advance screw may need adjustments ,can this be done correctly if not in the lake? and how?It idles a bit low so I assume it needs to go up a hair.<br />Any suggestions?
 

Chris1956

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Mar 25, 2004
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28,074
Re: boggs out/spark advance?

Laker, Here is the Link and Synch Info, Courtesy Clams Canino:<br /><br />Manual specs are different for each but this is close enough to get them all REAL close. This assumes nothing is broken or "wrong" with it. This also assumes that the timing pointer is properly adjusted (if adjustable) to accurately read TDC of the #1 piston.<br /><br />This basic procedure will work for all the 2/3/4/6 cylinder inlines from 1960 to 1988. It's not for the newer 3 and 4 cylinder loopers.<br /><br />Engine off<br /><br />Disconnect throttle cable<br /><br />Pull throttle arm to full throttle and verify carbs open fully. Adjust main throttle stop so that the carbs are JUST hitting thier own little throttle stops. The idea here is that you want the screw stop and NOT the carbs acting as the "final stop" for your throttle lever.<br /><br />Return the throttle to idle, carbs should be closed. Set all idle screws to 2 1/4 turns out from lightly seated.<br /><br />Remove all plugs except #1, hook a timing light to #1. Then follow the narritive.<br /><br />When the throttle is in the idle position the carbs should be fully closed and the ignition retarded. It the amount of retardation that determines your idle speed and is set later with the idle stop screw. <br /><br />Timing Event One - throttle pickup.<br />As the throttle is advanced, the spark timing advances toward TDC and then to before TDC. As the timing is just passing TDC the 1st (minor)throttle pickup should hit and start to open the carbs. Use the timing light. Adjust the tang or trigger screw to make this a reality. All of them are speced different, but if the 1st pickup hits at 3-4 degrees BTDC advance - you win. Use the timing light with a friend cranking it to complete this setting.<br /><br />Timing Event Two - max advance.<br />As you continue to advance the throttle the timing will advance while the carbs slowly open a bit more. The next adjustment is max advance, this is the point where the distibutor (or trigger) can advance no more. Set the max-advance stop to 21 degrees for "direct charge" inlines and 34 degrees for the older crossflows. Use the light, - err to the side of caution.<br /><br />Right after max advance, further throttle motion should cause the second throttle pickup to hit and open the carbs to full. You already set that -now verify it.<br /><br />Leave the throttle cable disconnected and go to the water. Leave the boat strapped to the trailer and back it in so it's deep enought to run. Have a friend crank it while you operate the choke and throttle. Warm it up at 1500 rpms's.<br /><br />When "warm" adjust the idle stop screw for about 800 rpm and then ajust your idle needle(s) in (one at a time) till the motor stumbles. Quickly backing it out 1/2 turn from "stumble" will usually save it from needing a re-start. Do that for all the idle screws. Re-set idle stop for 800.<br /><br />Now have your friend put it in gear (make SURE you are on the transom NOT in the water) and reset your idle stop for as low as you can get it. 500-600rpm is great if your old reeds will let it idle that low in gear. Now, re-adjust the idle screws, in to stumble, then 1/2 turn out. When you've gone back and forth with that a few times and have it "perfect" - adjust each one out 1/4 turn.<br /><br />Reset the idle stop so that it's about 700-800 out of gear and 500-600 in gear. Sometimes bad reeds won't let you get that low, you've GOT to get it under 1000 in neutral (worst case) to avoid beating up your lower unit when you shift into gear, even 1000 is "bad" but like I said "worst case".<br /><br />Now adjust (and hook up)the throttle cable so that with the shifter in neutral, there is light to moderate pressure holding the throttle arm against the idle stop.<br /><br />Take the boat off the trailer and go out in the water. Try the hole shot. If it falls on it's face try adjusting the idle screws out 1/4 turn at a time (all of them together) till you can get a hole shot. You can kind of do this on the trailer at the ramp, but it's not really safe for you, the boat, or the tow vehicle.<br /><br />You're done.<br /><br />-W<br /><br />--------------------<br />C.C. Marine - Lake Hartwell S.C.<br />(cc-marine@earthlink.net)
 

laker925

Petty Officer 3rd Class
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Jun 10, 2005
Messages
85
Re: boggs out/spark advance?

I had the carbs just rebuilt by a dealer and they said they had it set right on the idle screws/idle stop and that the spark advance may need adjusting.<br />How do I set it for 21 degrees?The timing kicks in and starts fine since replacing with new belt(a dial indicator was used to get the pointer on the right mark and TDC@ cyl #1).The dealer used the light on it also and each hit fine.<br />Do you advance the spark advace screw "in" (for the acceleration to kick in) or turn it "out?"<br />Also ,I do not have a tach so exact rpm cant be measured with what I have(it is a mid 70s model).<br />What did it mean use the light- err to the side of caution?<br />Any help is appreciated ,I am so so close to getting it perfect but I just need to fine tune what has not already been done,or do what can not be done unless it is on the water.
 

Chris1956

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Mar 25, 2004
Messages
28,074
Re: boggs out/spark advance?

Laker, I guess I do not understand your questions(s). It is necessary to use a standard timing light to set the primary pickup and max spark advance of 21 degrees BTDC, per Clam's procedure. Clams also warns not to set the max spark advance any higher than 21 degrees. He says err to the side of caution, which means when in doubt, set the spark advance to less than 21, instead of more.
 

laker925

Petty Officer 3rd Class
Joined
Jun 10, 2005
Messages
85
Re: boggs out/spark advance?

I guess I will be able to tell when I have the timing light where it is set.What does it do ,motor wise, if set too low ,and also if set too high?
 

Chris1956

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Mar 25, 2004
Messages
28,074
Re: boggs out/spark advance?

Laker, If you set your max timing at greater than 21 degrees BTDC, your motor may incur damage. if you set the timing less than 21 degrees BTDC, the motor may run a bit slower than it is capable, but this setting will not damage it.
 
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