Rebuild Complete!

[FreeBeeTony]

I finished the rebuild of my Mercruiser 160. <br />Bored out 0.030 over w/ new pistons, bearings, rings, oil pump, fuel pump, water pump, starter, rebuilt carb, switched to electronic ignition....<br />Started it for the first time today in the boat!<br />Started right up! Had to adjust the valves, (they were too tight) and the timing and it ran great! Got it to idle smooth at 800 RPM in a few minutes.<br />The problem with the timing is as follows: the engine is a '67, no visible signs of any timing marks. I made a mark on the damper and what is left of the timing mark on the block at what I thought was #1 TDC (piston up and both valves closed). When I checked the timing with a light I was way off my mark. I adjusted the timing by ear, found the sweet spot for best rpms at idle. I know my marks must be off but I wonder how well I set the timing by ear? Any advice here?<br />Do you think I am close enough? Seems to run real smooth in the driveway!!! I am very pleased thus far. Now I have to install a new impellar in the outdrive and a new trim pump. Almost ready for the water!

 

[anesthes]

Re: Rebuild Complete!

I'd pull the balancer off and get another one with a mark.<br /><br />It takes a long time to set timing by "ear".. <br />This boat has advance right? whats it advance out to?? When we build cars, we figure out the timing on either dyno, or from hours of running with a scanner.. You want your initial timing just to idle, but most importantly your advance so when its done its in the right spot.<br /><br />Though with your overboring, your timing specs prolly wont be exact to factory anyway.<br /><br />-- Joe

 

[magster65]

Re: Rebuild Complete!

Yeah, buy a new balancer. Too much total advance will ruin all your hard work. Take no chances

 

[SeaMasterZ@aol.com]

Re: Rebuild Complete!

timing is crankshaft position related to the actual spark ... overboring would have no effect on this, nor would stroking, its all degrees, and they dont change

 

[FreeBeeTony]

Re: Rebuild Complete!

At this point a new balancer would mean I have to remove the engine from the boat again. I really don't want to do that! <br />Master65, if I understand you correctly I may have overadvanced the spark by timing by ear? I turned the distributor for the highest rpm's at idle. Should the rpm's be the greatest at the correct timing point? Now I am worried!

 

[MrBill]

Re: Rebuild Complete!

Vacuum gauge will detect improper timing and can be used for setting timing, both at idle and for timing advance. Not quite a dyno but much better than by ear.

 

[FreeBeeTony]

Re: Rebuild Complete!

MrBill, that sounds great but there aren't any vacum ports on this engine! Any other way of doing it?

 

[magster65]

Re: Rebuild Complete!

Yes. The 'best idle' setting for your timing is likely too far advanced. No worries but don't run at higher rpm's until you get it set (it may suffer from detonation). Get your TDC #1 (make sure it's right on) and scribe a new line on your balancer, get a good timing light and set it to whatever it's suppose to be. This is a very important process, don't take any chances. Enjoy!

 

[llerrad]

Re: Rebuild Complete!

Too advanced it will knock, too retarded no power so if you feel good with it by ear go with it. I have gone by ear many times with out harm.

 

[magster65]

Re: Rebuild Complete!

Yeah sure, way too far advanced will knock. A few degrees won't and it'll melt pistons or break rings at sustained high rpm.

 

[anesthes]

Re: Rebuild Complete!

<br />timing is crankshaft position related to the actual spark ... overboring would have no effect on this, nor would stroking, its all degrees, and they dont change <br />

Of course they do. Boring and stroking a motor completly effects your power curve and timing needs. You may find that places where you were 1 degree from knock, now you have headroom, and the other way around at other rpm vs load points. Not to mention his fuel requirements might be different.<br /><br />Not to get off topic, but this is why I like FI tuning. You can't really put a scanner/laptop on a boat and get a good idea of what your performance is.. <br /><br />

<br />Yeah sure, way too far advanced will knock. A few degrees won't and it'll melt pistons or break rings at sustained high rpm. <br />

No actually, what you'll do is knock during gross acceleration under load. And a few degrees could matter. When you set timing up for a motor, you usually want to be within 1-2 degrees of knock for max spark advance. You lose power otherwise. Too much advance and you'll detonate. I imagine marine engine builders advance as much as possible, since they list min. octane requirements. <br /><br />And you usually don't melt pistons (though I have seen it happen). They usually crack in the center. I've seen cheap iron rings melt or break, and then get stuck up top which causes a disaster.<br /><br />-- Joe

 

[FreeBeeTony]

Re: Rebuild Complete!

Now you guys are scaring the S**T out of me.<br />I am going to look closer at the damper to find the timing mark. The problem is the marks on the tab on the block are very corroded. I can't do any damage running it in the driveway can I?

 

[kenimpzoom]

Re: Rebuild Complete!

You should be able to determine TDC on the balencer by using some kind of method to stop the #1 piston. There is a special tool (I think) that you screw into the #1 spark plug hole which extends into the cylinder to where it contacts the piston near TDC.<br /><br />Once you install the tool, rotate the engine by hand till it stops, put a mark on the balancer, then rotate opposite way till it stops, put another mark on the balancer.<br /><br />Then put a mark halfway between the two marks and now you have TDC. It helps if you can screw a degree wheel on the balancer.<br /><br />Ken

 

[anesthes]

Re: Rebuild Complete!

I'd replace it.. If its that worn, chances are the rubber has turned to crap and it might come apart eventually. <br /><br />No you can't do any damage without load unless your soo far advanced that it overheats, but I surely doubt it.<br /><br />-- Joe

 

[FreeBeeTony]

Re: Rebuild Complete!

Found the timing mark on the damper!<br />I was too far advanced. I set it so the timing mark is half way between the center of the tab on the timing cover and the advanced side of the tab. I can't read the marks on the tab, I'm assuming the center is 0 degrees. I had to reset the idle and adjust the idle mix screws. Starts right up and I can accelerate in the driveway without any pops or anything. I think this is as close as I am going to get it before I take it out on the water. I have it idling at 800. Is that too low? Will the idle rpm's go down when it's in the water turning the prop at idle? (like an automatic car tranny in park and in gear?)<br />Next project is to get the outdrive ready! Thanks for the help so far!

 

[horndog]

Re: Rebuild Complete!

idle speed for a STOCK 160 is 500-600 and timing is 6 degrees BTDC.<br /><br />overboring to .030" will affect timing since you are creating more build up of pressure earlier in the compression stroke. You may try it at stock and see what happens. I don't have the correct answer for you, maybe call an automotive engine shop that specializes in rebuilds and ask them about timing.

 

[FreeBeeTony]

Re: Rebuild Complete!

WOW.......500-600 sounds pretty low!

 

[magster65]

Re: Rebuild Complete!

I'd set your idle to 600-650 rpm in gear.

 

[horndog]

Re: Rebuild Complete!

oops! I forgot the all important phrase... 500-600 IN GEAR

 

[FreeBeeTony]

Re: Rebuild Complete!

So.....800 in neutral in the driveway is probably a good place to start!<br /><br />Thanks again........<br /><br />Now on to the outdrive......see my other post.