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Interesting timing conundrum-AQ131A

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film842

Contributing Member
After months of engine work replacing bits and pieces, I finally was able to give my boat a good run and it seems to be running very well. However, I'm new to power boating and so I have to check all my assumptions against those who have experience.

Here's the odd bit: Base timing on my engine is supposed to be 8 degrees BTDC. At that setting, it does not run very well at all. When I advance the throttle, it chokes and dies. If I set my base timing to around 14 degrees BTDC, she runs like a champ...literally. Starts immediately and runs great at speed. Or at least it seems so to me.

It has been suggested on the Bayhliner forum that I check timing at speed and should find 32 - 36 degrees and I will do that.

However I don't want to harm my engine even though it seems to be running fine. Anybody have any thoughts on this?
 
If you have points and condenser, you may want to check the dwell and also make sure that the timing belt is installed correctly and the ignition leads go to the correct spark plugs. Also, you may want to check that your timing light does not have an "advance" feature that could be giving a false reading.
 
Mike, I read your thread on the BOC.
Several things to note regarding mechanical advance and ignition timing regarding BASE advacne and TA.

BASE is BASE.... no mechanical advance taking place.... it's just a locked in advance by nature of where the distributor housing is in relationship to the crankshaft, and when turned at an RPM below where any "Centrifugal" advance is occuring.
If weights and springs are all good, this keeps the distributor in BASE mode, so to speak.

Mechanical advance is what occurs within the distributor's centrifugal mechanical mechanism, and is above and beyond BASE!
Done via weights, cams, springs, etc.

If the mechanical mechanism is NOT able to offer the advance nessary, then BASE must be increased to achieve TA.... but this throws BASE off.
Hence the double edged sword! :mad:

Your distributor may need to be sent out to a shop that corrects the mechanism and re-sets, or re-curves it.
They will need your engine specs!
When you get it back, it should be dead on!

Also, and recently being discussed on the other forum, is the importance of the RPM at which TA is Full IN!
NOT before..... and NOT after!

This is why looking beyond BASE, and strobing your timinig marks as you increase RPM is important!
See OEM specs for this.

Eduardo touched on something..... and that is the use of digitally advancing timing lights.
With this engine, and with the way in which the aluminum cover is marked off in degrees, there is NO need to use a digitally advancing light.
Increase RPM as you strobe the marks, and you will see in "real time"/"real degrees" what your advance is doing.

Eduardo, I know you love your DA timing light! :D
.
 
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check the timing belt to see that its not off by a couple of teeth and all the pulleys are alligned properly, if they are not this is one of the problems it could cause, i went through the exact same symptoms and after checking i had to move my gear on the cam over 3 teeth on the timing belt, but before was just as yours ran fine when i would advance the distibutor,but horrible when proper timing was set.
 
el_pescador said:
If you have points and condenser, you may want to check the dwell and also make sure that the timing belt is installed correctly and the ignition leads go to the correct spark plugs. Also, you may want to check that your timing light does not have an "advance" feature that could be giving a false reading.
Click to expand...

Not to keep beating a dead horse, but my assumption had been that as long as the cam mark, accessory pully mark and crankshaft mark were lined up correctly, (cylinder #1 at TDC) it did not matter how the belt went on.

Do I have that wrong?
 
film842 said:
...my assumption had been that as long as the cam mark, accessory pully mark and crankshaft mark were lined up correctly, (cylinder #1 at TDC) it did not matter how the belt went on.

Do I have that wrong?
Click to expand...

You have it right. However, timing belts can slip, in which case your valve and/or ignition timing will change.
 
My belt keeps jumping andi set thhe timing correct. New belt. Tensioner and spring? What should l do . I have a push rod motor i can put in bot have yo change lots of stoff. But i have it all. I wish i could figure it out.
 
Ayuh,..... This is a 13 year old thread,.....

Start a new thread of yer own, to get attention of folks still posting on here,.....
 
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