70hp 3 cyl Quick timing Question

[westexasrepublic]

max spark 27? BTDC @crank speed 300rpm
(which is 23? BTDC@ 5500rpm)


what should my max timing show @ cranking when setting the timing in my garage at home? 27? or 23??

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

[edit] isolated the wire, set timing to 27?, is that right?

 

[daveswaves]

Re: 70hp 3 cyl Quick timing Question

[edit] isolated the wire, set timing to 27?, is that right?

If you set the timing to 27 with the engine cranking at 300 rpm or so then it will be correct, the timing will "fall off" to 23 degrees when the engine is running at 5500 rpm or WOT. The idle stabilizer circuit uses that 4 degrees of extra timing to maintain a stable idle. If you are removing the idle stabilizer circuit, which many people do, time it to 23 degrees.

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

I didnt think a 79' Mariner 70hp ser#5362284 had an idle stabilizer? if I do, where do I need to be looking?

pretty sure it doesnt.

 

[daveswaves]

Re: 70hp 3 cyl Quick timing Question

I didnt think a 79' Mariner 70hp ser#5362284 had an idle stabilizer? if I do, where do I need to be looking?

pretty sure it doesnt.

Actually Im pretty sure it does not as well, I did not look at the date of your engine. 27 degrees it is, at cranking speed.

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

so for sure 27?? the reason I ask is because I read the "link and synch" thread and also seen a video online that says to set your max timing 4? less than mfg recommend, what gives?

http://forums.iboats.com/showthread.php?t=168855

 

[emckelvy]

Re: 70hp 3 cyl Quick timing Question

The reduced timing suggestion has to do with the the fuels available to us today (gasohol), back in the day they were a lot better (especially without the added alcohol which will make any engine run leaner).

Plus the little 3-cyl is highly-stressed and if you want it to live in today's environment you need to reduce the max timing and always prop to achieve the upper band of the recommended WOT rpm with a light load. Even the Inline Sixes were backed off from 21 deg advance to approx 18.

You'll get a bit less performance with the reduced max spark advance setting, but better that then a fried motor!

BTW don't recall any type of an idle stabilizer on this motor, the ADI-ign timing retard function at WOT is handled by the switchbox(es).

HTH...........ed

p.s. another thing that will help your 3-cyl live is to scrupulously maintain its cooling system including impeller renewal every year, and performing the mod which moves the telltale water outlet from the side to the top of the block. This mod ensures the water passages are fully flooded and purges any air bubbles, to prevent the forming of "steam pockets" which can stress #1 cyl or even crack the block.

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

ok so now im more confused, cuz I understand why it should be less, but less than what? should I set timing to 27,23,21 or now 18??

according to the posted pic what should my timing be?

 

[daveswaves]

Re: 70hp 3 cyl Quick timing Question

ok so now im more confused, cuz I understand why it should be less, but less than what? should I set timing to 27,23,21 or now 18??

according to the posted pic what should my timing be?

Well considering my track record on this particular post feel free to ignore my answer:redface:, Reduce your timing from 27 at cranking speed to 25 at cranking speed. I promise, from now on I will engage brain before starting typing.

 

[sschefer]

Re: 70hp 3 cyl Quick timing Question

Listen to the man. He knows his stuff. 27 was the recommended setting in 79. If you can find fuel without E-10, MTBE or Bio Diesel additives today's setting would be 23-25 degrees max @ cranking speed. If you run fuels with any of the mentioned additives then drop it to 21 degrees max @ cranking speed.

On these engines you should be using a accurate hand held tach often known as a Dwell/Tach to make sure your cranking speed is very near the 300 rpm speed necessary for setting the initial timing.

The label on your engine has been recalled, the replacement label states that you should check the latest manual revisions for changes to the recommended settings.

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

Well considering my track record on this particular post feel free to ignore my answer:redface:, Reduce your timing from 27 at cranking speed to 25 at cranking speed. I promise, from now on I will engage brain before starting typing.

Im not ignoring your reply, and I appreciate your input....

however I am getting conflicting information. All im trying to do is organize the information and better understand timing and how its been affected since the original information from 1979. see where im coming from?

 

[daveswaves]

Re: 70hp 3 cyl Quick timing Question

Im not ignoring your reply, and I appreciate your input....

however I am getting conflicting information. All im trying to do is organize the information and better understand timing and how its been affected since the original information from 1979. see where im coming from?

No problem, bottom line is that todays fuel does not have the octane rating that fuel had in 1979. In addition, the method of calculating octane has changed over the years. The addition of alcohol to the fuel has complicated the matter since alcohol has an affinity for water and it will carry that water with the fuel and oil mixture resulting in a lean mixture. Lean mixtures preignigte easily. Deadly combination's for these engines. By reducing the timing you are adding a safety margin. My experience with the inline 6 engines of the day is that reducing the timing by 2 degrees has no detrimental effect on the engines performance.

 

[RaScLeS]

Re: 70hp 3 cyl Quick timing Question

where is a how to for the telltale mod and what additives can be used so it burns better or more safely?

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

No problem, bottom line is that todays fuel does not have the octane rating that fuel had in 1979. In addition, the method of calculating octane has changed over the years. The addition of alcohol to the fuel has complicated the matter since alcohol has an affinity for water and it will carry that water with the fuel and oil mixture resulting in a lean mixture. Lean mixtures preignigte easily. Deadly combination's for these engines. By reducing the timing you are adding a safety margin. My experience with the inline 6 engines of the day is that reducing the timing by 2 degrees has no detrimental effect on the engines performance.

and thats what stems my confusion. see back on a previous post you said this

"Actually Im pretty sure it does not as well, I did not look at the date of your engine. 27 degrees it is, at cranking speed."

and now your suggesting it be retarded a bit.

 

[duff]

Re: 70hp 3 cyl Quick timing Question

My question for you westexasrepublic is this....

are you looking for an answer or someone to agree with whatever documentation you are reading?

I was good with this post untill about your 4th post. well this said this or that these guys are offering thier time to help and everytime they have given me advice it has been dead on! even if it was not what my manual said. the manual will work also but these guys are trying to save you some head aches later on by addinf a little safety to you motor. it is your choice use the manual or the advise on here. it is your motor safety or right your decision!!!!!

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

consistency not right or wrong.

read through all the post and you tell me what the degree of timing should be based on the MANY different answers I have received. The only person that has given me an exact answer also implied a different answer.

 

[daveswaves]

Re: 70hp 3 cyl Quick timing Question

and thats what stems my confusion. see back on a previous post you said this

"Actually Im pretty sure it does not as well, I did not look at the date of your engine. 27 degrees it is, at cranking speed."

and now your suggesting it be retarded a bit.

And as I mentioned on my following post, clearly my brain and my fingers were not talking to each other. The part of my brain that thought your engine was newer was still influencing the part that looked at the sticker. I was corrected by another poster, quite rightly so and since you were still looking for consistency I made what is my normal suggestion....retard the timing by 2 degrees. Its up to you to make a decision based on the information you receive. If you are not happy with the information...well..it was free.
I hope you find a thread of consistency here in that posters have suggested that you retard the timing and that the sticker on your motor was recalled by the manufacturer and replaced by a reference to the latest service specs. Mercury knew there was a problem.

 

[sschefer]

Re: 70hp 3 cyl Quick timing Question

And as I mentioned on my following post, clearly my brain and my fingers were not talking to each other. The part of my brain that thought your engine was newer was still influencing the part that looked at the sticker. I was corrected by another poster, quite rightly so and since you were still looking for consistency I made what is my normal suggestion....retard the timing by 2 degrees. Its up to you to make a decision based on the information you receive. If you are not happy with the information...well..it was free.
I hope you find a thread of consistency here in that posters have suggested that you retard the timing and that the sticker on your motor was recalled by the manufacturer and replaced by a reference to the latest service specs. Mercury knew there was a problem.

Yup, just ask any 2+2 owner. FYI the term recalled probably isn't correct but if you took your engine in for service the mech was supposed to change the sticker. Mine was changed and is probably due for another. Mine say's 25, the service manual say's 27, Seloc say's 20-22. I set it to 21. How's that for consistency. Good god man, do you not realize you're dealing with the boating industry. This aint Indy Racing.

 

[westexasrepublic]

Re: 70hp 3 cyl Quick timing Question

Yup, just ask any 2+2 owner. FYI the term recalled probably isn't correct but if you took your engine in for service the mech was supposed to change the sticker. Mine was changed and is probably due for another. Mine say's 25, the service manual say's 27, Seloc say's 20-22. I set it to 21. How's that for consistency. Good god man, do you not realize you're dealing with the boating industry. This aint Indy Racing.

I think you understand my point. I dont know if my sticker was replaced and those are the updated numbers.
.............So not to further any animosity toward me or the issue, im going with +,-27? leaning more towards 25?