Quick Timing Questions

[R. Wood]

For break in of reman'd powerhead supplier recommends timing should be retarded from factory settings by 2 - 4 degrees (factory setting is 28 deg. <br /><br />For clarity, timing should then be set between 24 - 26 deg?<br /><br />Also should timing remain retarded for complete 10 hr break in or?

 

[rodbolt]

Re: Quick Timing Questions

hello<br /> if properly rebuilt with the proper quality parts timing should be set according to specs and the manufacture's breakin procedure used. we dont retard and advance timing for breakin or run. just make sure quality parts are used and the reman will perform as a new unit.<br /> good luck and keep posting

 

[R. Wood]

Re: Quick Timing Questions

I'm not really not clear on why the timing should be retarded for break-in (less stress on components?), can anyone explain?<br /><br />The directions from the reman'd supplier did indeed indicate the timing should be retarded. I've also seen posts here recomending the same(?) adding to my confusion<br /><br />Is retarded indeed 24-26 deg?<br /><br />Thanks for feedback.

 

[Dhadley]

Re: Quick Timing Questions

Lets start with what motor you have. A model number will tell us what you have.<br /><br />Theres a couple of thing to remember as to why a supplier will recommend that. Rodbolt is absolutely correct that it should be set up as intended from the factory. If you are doing the rebuild yourself and are confident that you found the cause of the original damage and corrected it, the motor should be fine with standard timing. Remember, a damaged piston is a result, not a cause. When good techs like Rodbolt do the rebuild I have every reason to believe he has found and corrected the cause.<br /><br />When a rebuilder or remanufacturer ships a powerhead to someone they have no way to know whether or not the person doing the work has even found the cause, much less corrected it. They have no way to know if the installer will set the timing pointer correctly or if they set the timing correctly. They have no way of knowing what the original problem was. They have no way to know if the motor will even be broke in properly. So to try and be safe they recommend setting the timing back. That does a couple of things but the most important is that is draws specific attention to the timing proceedure. It also insures that the motor will be looked at after a certian running time. <br /><br />Your supplier has made a recommendation which has prompted you to ask some very good questions. I would bet that if you called the supplier and asked that question at some point he would ask what happened to the original motor.<br /><br />You cant believe how many times we hear about how a certian motor is junk because the powerhead has been repalced or rebuilt several times and the exact same thing happens again and again. They keep repairing the effect but dont find the cause. And naturally warranty is expected. <br /><br />Hope that helps some. Good luck with your project!

 

[R. Wood]

Re: Quick Timing Questions

The reman'd head did not have a model # on the freeze plug, but I was roughly able to ID to a pre 1984 V4 115 crossflow flatback (recirc routing through #1 and #4 bypass covers) For reference it is replacing a 84 1.6l Sea Drive flatback.<br /><br />Previous failure was due to carbon build up on exhaust side of #3 cylinder (is coking the same thing?). I don't thing it ever saw a drop of engine tuner, which I now plan to do religously at least every 50 hrs.<br /><br />I've gone though the standard list of items, rebuilt carbs, replaced t-stats and impeller, <br />inspected all hoses / connections (all new last year with VRO), etc.<br /><br />Timing pointer adjusted to TDC for #1 cyclinder, adjusted the timing to approx 26 degrees (using J. Reeves static timing method, adjusted from approx 24 to 22 deg.)<br /><br />In board tank is mixed with 50:1 to run in parallel with VRO for break in. Started and idled motor on the muffs to verify warm up / cooling (no issues). Verified spark (no issues). Checked head bolt torque after first warm up / cool down (a few required some additional torque).<br /><br />My ??????'s<br /><br />Why would retarded timing be safe (less stress somehow)?<br />Is the timing adjustment necessary?<br />26 deg would be retarded (as opposed to 30 deg?) <br />How long shoud timing remain retarded (if at all)?<br />Can I expect a WOT RPM difference for the 2 deg retarded?

 

[R. Wood]

Re: Quick Timing Questions

^^^

 

[Dhadley]

Re: Quick Timing Questions

Timing for that motor is supposed to be 28 at wot under a load. I sure wouldnt run it at 30. Especially if its being lugged at all which it might be considering the past coking history.<br /><br />Joe outlines a very good way to get your initial but it still needs to be verified under a load at wot.<br /><br />BTW -- if all you changed in the pump is the impeller I would suggest you go back and change the liner and plate also.

 

[P.V.]

Re: Quick Timing Questions

Back in the '80's, OMC came out with a service bulletin pertaining to the need to "retard" the timing on many of their engines already in the field. Due to the loss of lead in the fuel we were then using, retarding the timing 2 degrees was necessary to "cool" down the combustion temps. (lead tended to reduces the piston dome temp) OMC provided small decals to install on each motor that explained the need for higher octane fuel to also compansate for "lower" quality fuel.... Some engines actually had to have thicker head gaskets to further reduce compression and... lower cylinder temps!!! Reducing timing 2 degrees will hurt this motor and I bet you would not even notice any difference !!!! I turned back many a customers motor timing and no-one ever compained of a lack of horsepower! Heck, most did not even know it was done!! Go ahead a turn it back 2 degrees and be safe!! OR.. leave it at 28 and always worry about it!!

 

[P.V.]

Re: Quick Timing Questions

OooPPppssss! Modify the above... Reducing timing 2 degrees will NOT hurt this motor!!!! My bad!

 

[rodbolt]

Re: Quick Timing Questions

2 degrees really wont make a rats hair anyway. but the final setting MUST be verified at WOT and thats the final answer.<br /> good luck and keep posting.<br /> PS to much retard and the exhaust temps skyrocket.

 

[R. Wood]

Re: Quick Timing Questions

Thanks to all for the info. <br /><br />I think it's great that everyone shares their knowledge regarding the finer points on how and why.<br /><br />Regarding the water pump, compelete assy has less than 50 hours so impleller only was changed. I'll<br />probably replace the plate and cup before next season. I plan to only get the 10 hour break in done and pull out. <br /><br />I have about an 1 1/2 on the break in with no issues. Idled and ran well. Next outing I plan to get the timing under load at WOT.