1976 Merc 1500 Dead in the water!!! Help please!

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!






AS you can see there is not verification of the SN on the motor. The swivel bracket SN is for a 1976 1500.

 

[Faztbullet]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

That block has been replaced sometime when it was in warranty as the replacement blocks did not have serial number and had to be stamped at dealer.. also you need the correct connections for plug wires into cap. Spark having to jump possible 3 air gaps(rotor to lead, lead to wire,wire to plug gap) can cause voltage drop at plugs.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Thank you for the response FaztBullet. I appreciate it. However, I've been a motorhead all my life and I can tell you the connections from the wires to the distributor and as effective as original if not more effective. As mentioned before I have this motor running which is much more than I could say about it when I purchased it. Regardless I could be better so I am looking for any insight. If I'm not mistaken the original wires, although screwed into the cap, were single wire solid core. These are multi-wire so there is much more opportunity for more contact than the single strand of the originals. If I resolve all other issues and still have a problem I will put the original style wires on. f
or now Im confident in what I have.

 

[mr 88]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

x2 don't care if you majored in rocket science,go stock on the plug wires setup.

.. also you need the correct connections for plug wires into cap. Spark having to jump possible 3 air gaps(rotor to lead, lead to wire,wire to plug gap) can cause voltage drop at plugs.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Feel free to share your logic on this. I know for a FACT I have as good or better electrical connection between the cap and wires and plug and wires as there was stock and a better wire than was around in 1976. I'm not loosing spark.

This is not any of my problem. Although it may look different to you it is a better connection than was supplied originally.

 

[mr 88]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Outboard plug wires are SOLID STAINLESS STEEL,resistance should be zero.If you are a ace mechanic and electrical wizard then why did you come on here asking questions when you know it all ? All done with trying to help people that ask for help then state they have all the answers when you suggest they do it the correct way.

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Well there is a simple test. Use the ohmmeter to prove you have zero resistance from the brass contact on the distributor cap and the spring ends under the spark plug boot. The original wires were stranded stainless steel and had crimped threaded ends that screwed into the distributor cap. The coil wire was screwed into the cap as well.

I still do not like the amount of advance you are using. Are you positive the timing pointer is set to TDC accurately?

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

THANK YOU CHRIS! I was waiting for someone to ask me what the resistance is. I know Mr. 88 is a pretty smart person however they did not ask me anything to prove what I'm doing was not as good or better and you have. Thank you. And yes I'm positive the pointer is correct as I've checked and rechecked it based on the latest suggestions on this post.

Anyway I checked Impedance as suggested and received no resistance on any of all 6 plug connections from distributor cap to plug. I checked it with a fluke 23 digital meter then rechecked it with a Simpson 260 analog meter because the needle fluctuation can be more accurate than the digital meter's rounding to the nearest tenth of an ohm. So truth be told EVERYTHING has some level of resistance however as stated before I can guarantee the connections on my distro cap to my plugs are AT LEAST AS GOOD AS STOCK.

So now that that is behind us... when I pulled the cap off I noticed the carbon pin had exploded in side the cap. So let's take a step back and ponder this for a second... Not only am I skipping spark from the rotor to the pin in the cap but now I'm JUMPING spark across a greater distance in the cap from the spring (which was still seated correctly but showing signs of burn) to the rotor and the motor was still running pretty darn good. I say this in comparison to how it ran when I got it. If someone else jumped in this boat and tried to drive it the way it runs they would take it to someone to be fixed due to having to feather the throttle so much around idle and shifting points however other than that it runs pretty good. So I ask that we put the plug wire issue behind us.

The lower housing seal right above the 2 small exhaust ports seems to be good enough to keep the exhaust gas from coming inside the cowl however I'm sure under "suction" it may flex enough to have an effect which may be part of the issue. After I removed the baffle and closed everything up I can feel quite a lot of air passing through the opening in the top of the cover even at idle and when its revved there is quite a draw coming in through there so my guess is that it may be creating enough vacuum to pull from that lower seal area.

Also I'll have it back on the water tomorrow (if I can find a carbon pin for the distro) and I'll try to advance the timing even more to see where it's sweet spot is. As I mentioned it's between 28-29* now and based on how it changed getting to that setting I think it may go more. It gets to 5300 rpm much quicker now than it did before. Actually before it struggled to get there with the covers on.

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

The exhaust from the idle relief ports will not be an issue, cowling seal or no seal. The joint between the powerhead and midsection is where the exhaust will leak from. Check the nuts for tightness and look for exhaust leaks there. Your motor looks just like my '77 Merc 1500. I think it therefore should be timed like mine. I would think you are somehow misreading the timing. Does you timing light have the biuilt in advance?

Are you sure the outer flywheel is installed properly? That is a real longshot, as it would need to be off a minimum of 45*.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Well I'd hate to think that as many times as I've checked it that it could still be off (flywheel position). I've set the position via dial indicator, etc. Right now when I go to TDC everthing lines up including the distro arrow and pully marks. Is there a specific process outside of all that has been listed here that will prove the correct location?

And no... my timing light has no advance and is not adjustable. However that last time I checked the timing the Brush and spring were in pieces in the distro so that may have thrown off the timing some however I would have assumed that to show less advance due to the spark delay. ??

I'll check the bolts/nuts and see. Thank you!

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

The simple screwdriver thru the top spark plug should get you close-enough to TDC to tell if your timing pointer is adjusted properly and outer flywheel is on connectly. You are checking timing on the top cylinder, right?

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Well that is what I assumed to be correct and yes it is set correctly

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

I checked the nuts that connect the powerhead to the midsection and although I could tighten them they all seemed to have tension on them and I didn't notice any exterior sign of leakage. I don't think it was leaking there.

What other areas, if any, would allow exhaust gases into the intake area?

 

[Chris1956]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

Gee, the only other place to let exhaust in would be the exhaust cover, but I would think you would notice that.

 

[rriddle99]

Re: 1976 Merc 1500 Dead in the water!!! Help please!

I'd like to thank everyone for their help with this thread. I have to say as of today it's running quite nicely. The 2 items I did today that played a part in this was replaced the brush and spring in tbe distributor cap and replaced the throttle cable. I also adjusting the timing more advanced (it was between 28-29* BTDC) I'm not sure now where it is, I'm guessing 30-31* however it was only a small improvement so I'll probably take it back to the 28-29* range just for safety purposes until I can figure out why it has to be so much different than standard.

Anyway... Thank you to everyone who contributed to this success. I bought a boat for $1200 that didnt float and seemed to be alergic to water and now my total investment is less than 2K and I must say it runs quite nicely. I still have work to do but what boat owner doesnt until they put it just they way they want it. Again... thank you all. From how everything came together I'd say that the throttle cable became pinched years ago and whoever owned it at the time tweaked it so far out in attempts to make it work that it ended up with me. This started back before 2007 as I found this boat advertised then on the internet (page is still up)

1978 Tenn. Valley Challenger
1978 Tenn. Valley Challenger

With the throttle cable the way it was it would not advance much at all to start the engine, only a few degrees from idle and it would barely high idle at 1400 rpm. Now it will high idle around 2000 and starts much easier and transitions between gear changes more smoothly. It will still die here and there but I think I can tweak the carbs to solve that. Right now I start it, warm it a little, reverse it off the trailer, turn it around and hammer it and I'm at 5300 rpm in no time.

Here are all the changes that put me here:
Carbs throughly cleaned and set as I mentioned previously
floats adjusted to spec
new plugs
new plug wires and coil wire
New internal wiring harness
New External wiring harness
Link and synched multiple times multiple ways (there are a lot of opinions on here as to how to do it)
Ended with 1st throttle/timing event setting at 6*
Final throttle/timing event around 28-29*
New brush and spring in distributor cap
New Throttle cable

The brush and spring made a noticeable difference today as well as did the throttle cable however the new throttle cable made the motor start and respond more like it did back in the 70's. Until this it was always running like and old motor that needed some help.

I'm officially closing this thread (if that really means anything) as the help I've received has put me where I need to be. I may start new threads as I come up with more questions however you all have saved me a LOT of money and I am very appreciative of that!

:happy: