Mercruiser Puzzler with Timing

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

Yeah, thats what I think is the some spert put the dog gone pulley on wrong, thats my educated guess! When I get back I will check that out. In regards to checking for TDC, this is CRAZY, but when we are talking degrees of rotation how exactly does one determine exact TDC with a screw driver? That is somewhat evading me!!! In regards to setting point gap then checking dwell, setting dwell is setting point gap right? Or are the two totally different adjustments? I know that in the service manual it tells me that you can EITHER set the point gap with the feeler gage or by a dwell meter. But I am kind of thinking that by checking dwell you are telling me that the points are hitting full surface to full surface and by checking point gap you are telling me that I am setting the distance between the two. Am I right? This whole points distributer is all sooo new to me!!!

It's almost like setting the gap is the initial setting & the checking the dwell is the final setting.....
Then you check timing.....
As for the tdc question.....
Pull the number one plug, insert the screw driver or pencil into the plug hole until it contacts the piston.....
Rotate engine till it (cylinder) goes up & starts to come down on the compression stroke.......

 

[pigrge]

Re: Mercruiser Puzzler with Timing

Thats what I figured on doing, but for those who read this and are in the same "boat" as me, there WAS something that I did understand in the manual, that I may point out. When rotating the engine, only rotate it one way, the manual says to NEVER rotate it the other way. That right? I will check that and then mark that as TDC. Thanks for all your help! Hopefully I will be able to get TDC and back out on the water this weekend.
One real quick question, I have a shop tach on my dwell meter, and it is not matching my tach on the boat past twenty five hundred, are shop tachs reliable up to that RPM? Prolly a stupid question, but just thought that I would ask! Thanks!

 

[JustJason]

Re: Mercruiser Puzzler with Timing

yep, only rotate it clockwise as facing the front of the engine. In the stern drive unit the input shaft and driveshaft are always in constant connection with the engine, if you tried to rotate it the other way you would be fighting, and would most likely damage, the water pump in the lower unit.

"are shop tachs reliable up to that rpm"
yes... and it's more than likely the shop tach is correct, and not the boat tach.
tach's work by counting the negative pulses that happen in the ignition system. when you take into account the 20+feet of wire, and all the little crimp connecters on it, plus any corrosion that are on the connecters and posts of the tach you get small voltage drops.. which ='s innaccurate numbers.
if you were to pop the tach out of the dash and hook it up side by side next to the shop tach in the back of the boat they would be a bit closer.
on a side note... i hope your in the water and not running the boat at 2500rpm on the muffs/garden hose... that's a no no

 

[JustJason]

Re: Mercruiser Puzzler with Timing

side note number 2... no to tach's are will ever be %100 the excact same... however the better ones are usually withing 95% of eachother..

 

[Buttanic]

Re: Mercruiser Puzzler with Timing

Dwell or more correctly dwell angle is the number of degrees the distributor rotor turns between when the points close to when they open. The point adjustment is simply how close each point set is to the point cam. The closer the points are to the point cam, the larger the point gap or dwell angle, thus the further away you will have less gap and lower dwell angle (less time the points are closed).

 

[JustJason]

Re: Mercruiser Puzzler with Timing

dwell angle is just an electrical measurement that confirms weather or not you got the gap correct.
if you guess at it or don't get it right the boat will more than likely run fairly well (unless you really miss) but don't be surprised if you eat up the points or blow the condenser in a few hours of running time.

 

[MikDee]

Re: Mercruiser Puzzler with Timing

By the way, the crankshaft pulley, and the weight on it, is seperated by a rubber layer, and it is possible for the rubber to slip, and the timing mark on the pulley to be off, or wrong, that's why you must sometimes physically find TDC by turning the engine over by hand as you have a screwdriver in the number 1 spark plug hole. Once you find TDC, you must then mark the crankshaft pulley yoursel, if the original timing marks don't line up.That will then be you Real TDC that you set your timing by, But first you must set your point gap, or dwell, because that will change your timing if you do it afterwards.

 

[Buttanic]

Re: Mercruiser Puzzler with Timing

By the way, the crankshaft pulley, and the weight on it, is seperated by a rubber layer, and it is possible for the rubber to slip, and the timing mark on the pulley to be off, or wrong, that's why you must sometimes physically find TDC by turning the engine over by hand as you have a screwdriver in the number 1 spark plug hole. Once you find TDC, you must then mark the crankshaft pulley yoursel, if the original timing marks don't line up.That will then be you Real TDC that you set your timing by, But first you must set your point gap, or dwell, because that will change your timing if you do it afterwards.

Not sure about a 1982 but earlier 120's did not have a rubber mounted harmonic damper, just a steel hub the pully bolted to.

 

[MikDee]

Re: Mercruiser Puzzler with Timing

Alrighty then , thanks for the tip.

 

[antsmands]

Re: Mercruiser Puzzler with Timing

Hello Pigrge;

Just wanted to quickly chime in on you points, condenser, gap and dwell issues. Get an electronic kit as I did and do away with all of the hassles. You will be sooooooooooooo Happy. No points gap to adjust or dwell angle to mess with. Only cost about $120.00 and worth every penny in my opinion. You can get it on iboats.

Check out the link:

http://www.iboats.com/Mercruiser_Sterndrive_Ignition_Parts/

A. Davis

 

[pigrge]

Re: Mercruiser Puzzler with Timing

Hey Thanks for the suggestion, can you please repost that link, it did not work for me thanks!

 

[Reel Poor]

Re: Mercruiser Puzzler with Timing

I don't know if this is the kit antsmands was refering to but.....Click the link Mercruiser electronic conversion kits

 

[antsmands]

Re: Mercruiser Puzzler with Timing

Hello Pigrge;

The link that Reel Poor posted is the correct link!

A. Davis

 

[picker523]

Re: Mercruiser Puzzler with Timing

I don't know if this helps but I had the same problem with my timing mark on my 87 3.0 and found another mark on the rim of the pulley against the engine which proved to be the correct mark. See if you have another one there.