'84 Merc 150 - how do I adjust timing?

[wired247]

Re: '84 Merc 150 - how do I adjust timing?

Oh . your'e in the outboard capital of the world, Florda. If Chris will do it for $200 run with that. FWIW, Ive used both on several builds and his reeds are better than the Boysenns.

You need bottom guided 3.125" ( plus the oversize ) piston ported Mercury V6 flat top pistons. No deflectors on the loopers like the Merc V6. The WSM's Carson sells are top notch. So are Vertex. Don't use the forged Wiseco's even though you can often get them cheaper than the cast alternatives. They heat swell and lock up in the bore and the bore needs to be real loose to use them.

Yes, You MIGHT be able to get by with boring just a few holes but it is a 30 year old motor so plan on the worst when you open it up. Let your machinist tell you which ones need to be bored unless you have a bore gauge. Bores wear at a taper and carb'd blocks usually wear out the bores pretty evenly.

The block stripped of the front half and everything else will be about 50 lbs.

 

[Dukedog]

Re: '84 Merc 150 - how do I adjust timing?

With Chris ya on tha right track. Hes got a good rep. and knows tha Merc stuff. Good machine work also. Talk to him.......Still think ya got an electrics problem so be prepared ta replace. Ya gotta figure out whats wrong and correct it. Just tha compression issue isn't gonna do some of tha things your sayin'. Still think ya need a KNOWN GOOD GAUGE. Cheapos (ie: harbor freight etc.) are notorious for low/erratic reading's.

Where in Fl. are ya. Know a few folks there........

Oh yeah. Ebay sucks for tha "not knowing stuff" guy parts buyin'. Lotsa folks there that don't have a clue but rely on punchin' up numbers. Kinda like "some" counter guys..........Ya know tha ones that hafta have a serial number or they're lost............jmo

 

[MAtkins]

Re: '84 Merc 150 - how do I adjust timing?

I'm in Orlando; lots of water here.
We've got an outboard machine shop here but he wants $450.00 to bore the block.
http://www.precisioncycleinc.com/cylinder_boring/cylinder-boring-pricing.html#

Is there any way I can test the electrics before I start tearing the motor down?
What is a compression gauge that's reliable that's maybe not tooo expensive?

 

[wired247]

Re: '84 Merc 150 - how do I adjust timing?

Thats way too much to bore a block. Thats too much to bore a V8 block. Chris Carson is your best bet. Machine shops have this way of making me angry sometimes.

It doesnt matter what gauge you use really if its consistent. If you always have 80 lbs on your bad holes and always have 115 lbs on your good holes you have a problem whether its accurate or not. If you wander about it pop a head off and look at the bore. Outboard bores can be pretty scary looking sometimes.

Sure you can test the electrics. You need a analog multimeter and a DVA adapter. You can download the guide from CDI.

 

[MAtkins]

Re: '84 Merc 150 - how do I adjust timing?

I rechecked compression using the same gauge.
It's pretty consistent and doesn't look good.
The #1 cylinder is consistently reading 80.
The rest are between 90 & 102.

So, maybe the electrics have a problem but the motor definitely needs rebuilt unless I'm still missing something.

What exactly can cause bad compression? Is always the condition of piston/rings/cylinder or can it be something else like a bad reed valve or something?

 

[wired247]

Re: '84 Merc 150 - how do I adjust timing?

Its rare for motors to have a reed valve go bad but a 30 year old motor is a 30 year old motor. Generally its bore condition. I'm willing to bet that if you opened up the #1 cylinder youd find gouging. Detonation or sitting too long without use and rings sticking can cause cylinder wall gouging that will make the compression drop.

 

[MAtkins]

Re: '84 Merc 150 - how do I adjust timing?

I've gotta figure at this point that a rebuild is definitely required, whatever else there might be wrong.
OK, thanks.
I'll start a new thread when I start the rebuild; sure hope you guys will be there to help me