Mercruiser Puzzler with Timing

[pigrge]

Hello,
I am new to this forum and pretty new to the wonderful world of boating. I have switched from cars to the water and am so far loving it. I purchased my new boat, well new to me that it, a 1982 Sea Ray with a 120 Mercruiser Serial number 6028915. I do have a small concern, I think. I have read that wide open throttle on this machine is 4200-4600. Out on the water I can only get 3500 on a good day normally I will only see 3200. Wayyyy below. But it seems to be running its little heart out. I have replaced all of the fuel filters, it is a brand new tank of gas, checked to make sure linkage was allowing it to go to full throttle. Now the tricky part of this equation, I bought a timing light today and checked it, it is WAYYYYYYY off. The mark on the crank pulley, if it were a clock is WAYYYYY over at about 11 o'clock and the stationary timing marks are at about two o'clock. Now the boat runs pretty smooth, NOTHING like what it is telling me it SHOULD run like with the timing sooooo far off, OTHER than not getting to the WOT. It also bogs down alot when first starting out. Not sure if that helps or not. I checked to make sure that my wires were on correct by pacing the number one cylinder at TDC or close to and then verifying that my distributer thing that makes the spark, excuse me, I think it is called the rotor? is pointing towards the number one post, and it agrees with what the timing light told me. The mark on the crankshaft pulley is right at the eight degree mark and the rotor is almost already half way between the number one cylinder post and the next cylinder post. So is it possible that the boat is running SOOOOOO far advanced? I also TRIED to put the timing mark at the eight degree BTDC mark by rotating the whole distributer and it did NOT want to run AT ALL!!!! until I took it back to where it was before. What is happening to my baby!!!!!! Any help would be GREATLY appreciated!!!!!
Ryan

 

[getinmerry]

Re: Mercruiser Puzzler with Timing

I don't think the problem was timing related...although it is now that you messed with the distributor. You have to jump out the timing advance to properly time the motor (I'm sure someone else will jump in with details).

With the info you gave, I'm guessing you have the wong prop.

Chuck

 

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

Hello,
I am new to this forum and pretty new to the wonderful world of boating. I have switched from cars to the water and am so far loving it. I purchased my new boat, well new to me that it, a 1982 Sea Ray with a 120 Mercruiser Serial number 6028915. I do have a small concern, I think. I have read that wide open throttle on this machine is 4200-4600. Out on the water I can only get 3500 on a good day normally I will only see 3200. Wayyyy below. But it seems to be running its little heart out. I have replaced all of the fuel filters, it is a brand new tank of gas, checked to make sure linkage was allowing it to go to full throttle. Now the tricky part of this equation, I bought a timing light today and checked it, it is WAYYYYYYY off. The mark on the crank pulley, if it were a clock is WAYYYYY over at about 11 o'clock and the stationary timing marks are at about two o'clock. Now the boat runs pretty smooth, NOTHING like what it is telling me it SHOULD run like with the timing sooooo far off, OTHER than not getting to the WOT. It also bogs down alot when first starting out. Not sure if that helps or not. I checked to make sure that my wires were on correct by pacing the number one cylinder at TDC or close to and then verifying that my distributer thing that makes the spark, excuse me, I think it is called the rotor? is pointing towards the number one post, and it agrees with what the timing light told me. The mark on the crankshaft pulley is right at the eight degree mark and the rotor is almost already half way between the number one cylinder post and the next cylinder post. So is it possible that the boat is running SOOOOOO far advanced? I also TRIED to put the timing mark at the eight degree BTDC mark by rotating the whole distributer and it did NOT want to run AT ALL!!!! until I took it back to where it was before. What is happening to my baby!!!!!! Any help would be GREATLY appreciated!!!!!
Ryan

Welcome to iboats....
Well, oit could be several things......
You are correct on the WOT though......
The numbers you mentioned above are where you want to be....
Could be the wrong prop possibly....
What size are ya running?....
When was a full tune up last done?.....
You will need to get some diagnostic equipment.....
A timing light with advance feature, to check the timing & insure the distributer is advancing correctly....
A tach & dwell meter, to check points dwell & verify that your tach is indeed correct......
Check the point gap with a feeler gauge.....
A compression tester to check the health of the individual cylinders....
Before ya go changing anything else, see what your timing & dwell readings are, so you have a base to start from....
Timing by ear is dangerous for the engine, if you are too far advanced, detonantion can cause a holed piston....
The odds of getting timing & dwell correct by eye & ear are nil......
Some other stuff....
Pull & check the condition of the plugs.....
At this time, you can check the timing by bringing the #1 cylinder to TDC by rotating the engine in the normal direction of rotation & placing your finger on the #1 plug hole until compression is felt as you near TDC.....
The rotor should roughly face the #1 terminal on the dist cap.....
Verify that each ign wire is functioning properly & that you have the correct 1-3-4-2 firing order.......

 

[pigrge]

Re: Mercruiser Puzzler with Timing

The last tune up was was done, I dont know! I just got the boat two weekends ago. The guy told me that the entire top end was rebuilt due to a piston needing to be replaced. What that entailed I have no idea! Regardless, the number that I get of the prop says 14 1/4 X 19. Please dont laugh as this was just a spare prop that I had. I figured I would try. I replaced the spark plugs and they seem to be in pretty good shape still. I was told in the Mercruiser repair manual to get a timing light WITHOUT the advance feature. What exactly does this do? As for setting the points and so on, might need a little advice. Thanks again in advance!

 

[firehog6305]

Re: Mercruiser Puzzler with Timing

replaced the top end because it needed a new piston the piston is in the lower half of the motor, now I have heard of people changing the pistons from the top, but in a boat it almost seems impossible, but your problem sounds more like a prop problem and oh ya welcome to iboats

 

[pigrge]

Re: Mercruiser Puzzler with Timing

Is the prop too big? I did kind of have to notch out the trim tab to put it on.........

 

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

Is the prop too big? I did kind of have to notch out the trim tab to put it on.........

Nope, you have something else going on.....
Since you have the Merc. manual....
Check what gap you have on the points before you replace them.....
Don't know why you would need a light without advance, but so be it.....
Make sure you have the correct setting....

 

[Don S]

Re: Mercruiser Puzzler with Timing

Are you trimming your drive up, or do you have it full down?

 

[pigrge]

Re: Mercruiser Puzzler with Timing

I do trim it up after she has gotten out of the hole, it comes up like maybe 100 rpm at the most!!!

 

[pigrge]

Re: Mercruiser Puzzler with Timing

Let me ask you this, my mercruiser manual covers marine engines from 1986 through 1990 something. My boat, as stated above is a 1982. Could there be something in this one that could be set up different, example being spark plug gap, timing, and so on? I am just shooting in the dark here. Also, the book tells me about the dwell meter. But it also says that I can use a feeler gage to adjust the point gap/dwell. This true? It DOES say that the use of a dwell meter is better and more accurate. But I do not have a dwell meter. I also dont have a shop tach. If anyone knows of a good website to get these things from recommendations would be greatly appreciated.
I was reading last night and it tells me that the procedure for adjusting the timing is to run the boat until it warms up, then check it while the engine is running at a "slow idle". What is this slow idle? I have the engine running at 700 like the book suggest normal idle is? Should I slow this down via the adjustment on the carb? Also after the "initial" timing is set at 8 BTDC I should then bring the engine RPM up to around 1800 and verify that the timing advace is working properly by watching the timing slowly advance with the RPM? This confuses me? How much advance are we talking about here? A couple of degrees? Because in the spec section it gives me a number of 32 degrees advance at 2000 rpm? Argh, this book is aggravating!!!!! Any help again! would be greatly appreciated!!!! Thanks!

 

[Windykid]

Re: Mercruiser Puzzler with Timing

Point gap is just what it sounds like the distance between the points.

Dwell is the angle between the points.

Make sure the timing is set at the proper RPM.

 

[pigrge]

Re: Mercruiser Puzzler with Timing

Yeah I knew what point gap is, just wondering if it REALLY makes that big of a difference to set that with the feeler gage as opposed to the dwell gage. Also, what IS the proper RPM when referring to "slow idle"?

 

[Buttanic]

Re: Mercruiser Puzzler with Timing

If you are good with a feeler gauge you can get within the dwell spec. range with new points, maybe not so easy with old used ones. The max advance will be well off the stationary pointer. 32 degrees max is correct. Slow idle is 500 t0 700 rpm. If the distributor advance is working properly then setting the timing at 8 degrees at idle it will then be 32 degrees at 2000+ rpm. After setting it at 8 degrees at idle speed up to 2000 rpm and see that it increases. To get an idea how much it increases is to measure the distance from the zero or TDC mark on the stationary pointer to the 12 degree mark. Lets say it is 1/2 inch. Now if the timing is 1/2 inch above the 12 degree mark it is 24 degrees, if it is 1 inch it is 36 degrees. This will give you a general idea of what it is at 2000 rpm

 

[whywhyzed]

Re: Mercruiser Puzzler with Timing

I recently put a different long block in my boat - the timing marks on the timing cover (tin indicator spot welded on) was in a different spot. When I reused the dampener from my old engine, the timing marks made no sense. I brought the engine to TDC and made my own ZERO mark on the damper with paint.

Maybe the same thing has gone on with your engine - might want to roll #1 up to TDC and see where your marks are.

I know the 2.5 and 3.0's have different locations of the tabs - and those covers would go on the 6 cyl...

 

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

Yeah I knew what point gap is, just wondering if it REALLY makes that big of a difference to set that with the feeler gage as opposed to the dwell gage. Also, what IS the proper RPM when referring to "slow idle"?

First ya set them with the feeler gauge......
Then ya check the dwell...
Then ya set the timing.....
Don't guess at the measurements, they are vital to proper performance....
550-600, in gear in water is the final idle, it can be as high as 100-150 more in neutral......

 

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

If you are good with a feeler gauge you can get within the dwell spec. range with new points, maybe not so easy with old used ones. The max advance will be well off the stationary pointer. 32 degrees max is correct. Slow idle is 500 t0 700 rpm. If the distributor advance is working properly then setting the timing at 8 degrees at idle it will then be 32 degrees at 2000+ rpm. After setting it at 8 degrees at idle speed up to 2000 rpm and see that it increases. To get an idea how much it increases is to measure the distance from the zero or TDC mark on the stationary pointer to the 12 degree mark. Lets say it is 1/2 inch. Now if the timing is 1/2 inch above the 12 degree mark it is 24 degrees, if it is 1 inch it is 36 degrees. This will give you a general idea of what it is at 2000 rpm

Well put ^^^^^.....

 

[pigrge]

Re: Mercruiser Puzzler with Timing

I recently put a different long block in my boat - the timing marks on the timing cover (tin indicator spot welded on) was in a different spot. When I reused the dampener from my old engine, the timing marks made no sense. I brought the engine to TDC and made my own ZERO mark on the damper with paint.

Maybe the same thing has gone on with your engine - might want to roll #1 up to TDC and see where your marks are.

I know the 2.5 and 3.0's have different locations of the tabs - and those covers would go on the 6 cyl...

For this I already did try and check TDC, and I will be damned if the timing mark on the crankshaft pulley was RIGHT AT TDC when my numero uno cylinder is at TDC. Thats where I am being thrown off. I am buying a dwell/tach meter today and going to give this a shot! Wish me luck!!!

 

[pigrge]

Re: Mercruiser Puzzler with Timing

So the problem seems to be getting worse. Well not seems to be, it really is. No the engine starts and IMMEDIATELY dies!!! aRGH!!! What I found what that the dwell was set just outside of the tolerance of 32 degrees at 34 so I brought it back down to 30 after a WHOLE LOT OF TROUBLE/TIME (my first time) after that, the engine started and immediately stopped after running for about one second total. Now, remember I told you that it took me a loooong time to get the dwell set right......could I have possibly flooded the engine? Even if I flooded the engine, if it starts and fires it SHOULD stay running? right? Maybe thats just me being naive about the boating world? What did I do wrong? Any help would be appreciated.
I thought that MAYBE the distributer could have been put in ONE tooth off, but found that at the bottom of the distributer there is a slotted end that I assume only fits one direction or 180 degrees the opposite direction, because I can slide it in whereever I want it to be, it just will not drop all the way until I get it to a certain point or 180 degrees from that point. Again, maybe I am just not getting it. What would make the engine fire up rev up and then stop by me just making THAT SMALL of an adjustment on the dwell??

 

[Haut Medoc]

Re: Mercruiser Puzzler with Timing

That slotted thing connects to the oil pump, you can move it with a screwdriver.....​

 

[pigrge]

Re: Mercruiser Puzzler with Timing

That slotted thing connects to the oil pump, you can move it with a screwdriver.....​

SEEE, I told you I am new!!!! But I will bet you I am not the first!!!!! Any ideas on the start/die situation?