Help with oil pump & mixture 84 Merc 150

[Doug57]

I have rebuilt my 84 merc 150V. Carbs boiled and rebuilt, bored 2 cylinders and honed 4, 2 new .030 oversized pistons, all new bearings, seals, gaskets, hoses, rings, cooling parts, STABILIZATION MOD (the cause). Now I don't know if I should leave the oil pump or go to mixing myself, what do you think? And I've read allot of opinions about break in. Should I use a 25:1 mix or stay at 50:1? If I keep the oil injection and mix about 12 gal will the 25:1 be ok until I know the oil pump is working ok? And if I mix myself will the mix pass through a water separator ok?

Your thoughts on any of this.

 

[j_martin]

Re: Help with oil pump & mixture 84 Merc 150

I have rebuilt my 84 merc 150V. Carbs boiled and rebuilt, bored 2 cylinders and honed 4, 2 new .030 oversized pistons, all new bearings, seals, gaskets, hoses, rings, cooling parts, STABILIZATION MOD (the cause). Now I don't know if I should leave the oil pump or go to mixing myself, what do you think? And I've read allot of opinions about break in. Should I use a 25:1 mix or stay at 50:1? If I keep the oil injection and mix about 12 gal will the 25:1 be ok until I know the oil pump is working ok? And if I mix myself will the mix pass through a water separator ok?

Your thoughts on any of this.

Did you change the oil pump drive gear while you had it down, or at least check it out?

Mix 50:1 in the main fuel tank. It should go through the filters with no problems. Set yer WOT timing at 23* and lose the stab module if you haven't yet. If you have confidence in the oil pump, use it. If you remove it, use the proper block off part to keep the pilot bushing out of the works.

hope it helps
john

 

[Doug57]

Re: Help with oil pump & mixture 84 Merc 150

Oil pump drive gear was in good shape. I just don't the plastic on steel thing. Think I'll mix my own. Is the block off part a Merc. part?

I ordered a @&$@% stabilization mod. So I can just lose it if I set WOT timing at 23*

See it's dummies like me that keep the parts business booming. oh well!

Should I just o my break in at 50:1

Thanks

 

[sschefer]

Re: Help with oil pump & mixture 84 Merc 150

Premix and never look back at a smoking time bomb again. Personally, I would not run the advance module or the idle stabilizer (not sure which one you have and some had both). I run mine at 22 deg WOT and would probably be fine at 25.

If you go with premix, drain your fuel tank and use fresh gas. Mix at 35:1 for the first 10 gals of fuel. Then 40:1 for the next 10 and 50:1 thereafter. At 35:1 you'll be running slightly lean so avoid anything other than short full throttle bursts and extended idling like trolling etc.Vary the throttle while crusing but keep it below 3000 RPM. At 40:1 you can pretty much begin to treat it as normal just stay away from full throttle runs over 5 minutes. At 50:1 your done and can run it normally.

I fill and stuff rather than using a block off plate it fixes the problem with #2 being a weak cylinder. To give youself the option to go back you would want to use the block off kit. I saw them on Boats.net. Do not remove the gear on the crank and make sure it's in good shape before you button up the crankcase. If you remove it you make # 2 even weaker from the added space which results in pressure loss.

 

[j_martin]

Re: Help with oil pump & mixture 84 Merc 150

I'll back up sschefer with a bit more info. The lean-rich comment has to do with fuel-air mixture. More oil displaces some of the fuel, making it leaner, and also increases the viscosity of the fuel, making it flow slower and thus slightly leaner. If you over oil and don't set your carburation for it, you can actually get excessive cylinder temps. Thus the break in sequence suggested.

Yer running steel cylinders, so break in is pretty important. Done well it will serve you a long time.

hope it helps
John