Quick Inline Primer

[Clams Canino]

While I'm here:<br /><br />If you have any of the "direct charge" Mercury inlines from the 1500 down to the little 402 40hp model. Remember the following.<br /><br />1. 21 degrees max advance isn't just the law - it's a good idea. If your timing sticker says anything from 23 - 27 degrees, it really means to say 21.<br /><br />2. Change the impeller at LEAST every other season. Every season if you run through a lot of sand.<br /><br />3. Keep the fuel system clean and use at least mid-grade gas.<br /><br />4. Make sure it's propped properly so that it runs near the upper limit of it's rpm range. This does not mean you have to run it there on a daily basis.<br /><br />5. Use a can of Mercury Power Tune AT LEAST once per season. I see more cylinders dead from coked up stuck rings - than any other single cause. <br /><br />-W

 

[jheron]

Re: Quick Inline Primer

Hey thanks CC What years are the "direct charge"?<br />regards Jon

 

[02'Crownline]

Re: Quick Inline Primer

yea...i have an inline 4 cylinder 40 hp 1992 is this direct charge?

 

[jfholijr]

Re: Quick Inline Primer

Thanks so much Clams.

 

[timbo1963]

Re: Quick Inline Primer

My 1971 4 cyl inline 650 says max timing is 38 deg. I don't think it would even plane my boat at 21 deg. Since timing drastically effects WOT I find your statement a little hard to believe. I assume by "direct charge" you are refering to the charging system.

 

[emckelvy]

Re: Quick Inline Primer

No, Direct Charge refers to the way the ports and pistons are designed. <br /><br />All of the old Mercs are Direct Charged. Most of the newer motor's (i.e. late 80's etc) are Loop Charged.<br /><br />Typically a direct charged motor will have a dome or deflector on the piston, whereas the loopers have flattops with lots of extra cutouts or ports in the piston and cylinder sleeve.<br /><br />Pro's and cons to each design, but loopers are typically more efficient, hp wise and fuel wise.<br /><br />That being said, we still like our old Stone-Age design Mercs! <br /><br />Nothing like a Tower of Power at full tilt to stir your innards!!!

 

[Scaaty]

Re: Quick Inline Primer

Those pics of that 63 500 Merc are great...still the most gorgeous motor made...love those tall 6 cyl models. Those and old Panhead Harleys were burned in my brain at a tender age, and glad of it!

 

[Clams Canino]

Re: Quick Inline Primer

Originally posted by Tim Frey:<br /> My 1971 4 cyl inline 650 says max timing is 38 deg. I don't think it would even plane my boat at 21 deg. Since timing drastically effects WOT I find your statement a little hard to believe. I assume by "direct charge" you are refering to the charging system.

You found it hard to read, therefore believe. <br />I specificly said the ones that wanted **23-27** degrees were the target. The "direct charge" motors started with the 1970 1350 and 1150 and then there was a slow trickle down effect to the smaller motors. They went away in the late 80's. Direct charge was a Mercury marketing term for thier modified crossflow scheme with a more "directed charge". The tops of the pistons had a strange "eyebrow" on the deflector dome.<br /><br />All the motors this applies to are knockoffs of the 99ci motor, be they 2, 3, or 4 cylinder variants. None off the 44ci four cylinders (like the classic design 40-50hp) are included, nor are the 4's made from the old 1100. If it wanted timing in the 30's - it's NOT one of them. That said... on todays gas... 32-35 degrees is safer for the old crossflows than timing into the high 30's.<br /><br />-W

 

[Clams Canino]

Re: Quick Inline Primer

Originally posted by 02'Crownline:<br /> yea...i have an inline 4 cylinder 40 hp 1992 is this direct charge?

No... that's the 44ci block. If it was the TWO cylinder 402 (40hp) then it would apply. However, the part about sticky rings and Power Tune applies to ALL of the inlines.<br /><br />-W

 

[Clams Canino]

Re: Quick Inline Primer

As a quick note - most of the "Direct Charge" motors had a little sticker advertising just that.<br /><br />The 70 triple was one, as was the 80/85hp four, and the 40hp twin.<br /><br />-W

 

[timbo1963]

Re: Quick Inline Primer

Yep, your right I read it wrong. Sorry.

 

[02'Crownline]

Re: Quick Inline Primer

yea thanks clam just wanted to clarify that.. so my 40 has a different block then all the rest... it is a 40 hp classic.. and robby yea i agree, we still own a 1963 dorsette el dorado with a 1963 merc 500(identical to the one in the pic) that my great grandpa had bought new then.. its great i love it

 

[Clams Canino]

Re: Quick Inline Primer

The 40ci Thunderbolt Four block appeared in 1949 with the 44ci "Super Thunderbolt" appearing in 1958. Somewhere in the mid-90's the Super Thunderbolt four finally went extinct, virtually the same as it was in 1958 save for bolt on stuff.<br /><br />It's not that your block is "different" - but it's not a "direct charge" motor. Evolution stopped on the 40-50hp block in 1958, while other stuff moved on. <br /><br />All those blocks time at 32-35 degrees and are very, VERY reliable little outboards.<br /><br />-W (who has a 1958 44ci waiting to power a barge someday) <br /><br /><br />

Originally posted by 02'Crownline:<br /> yea thanks clam just wanted to clarify that.. so my 40 has a different block then all the rest... it is a 40 hp classic.. and robby yea i agree, we still own a 1963 dorsette el dorado with a 1963 merc 500(identical to the one in the pic) that my great grandpa had bought new then.. its great i love it

 

[stant1man]

Re: Quick Inline Primer

Interesting stuff clams, i have a 72 1150 and will be setting up the timing just shortly. Do you not gain performance from enhancing the timing from 21 to 23-27? If i set it like you say will that not cost me power and fuel?

 

[emckelvy]

Re: Quick Inline Primer

You will certainly gain performance if you advance the timing beyond what Clams recommended.<br /><br />HOWEVER, any performance gains will be negated when the resultant detonation lunches the motor!!!!!<br /><br />These old Mercs simply cannot tolerate today's lower quality fuels. The recommendation to reduce the timing advance settings came from the factory years ago, and is still good advice today. You'd do well to heed it and your motor will be happier for it.<br /><br />HTH and Good Luck.......ed

 

[WillyBWright]

Re: Quick Inline Primer

Today's gasoline is not like the gasoline of the 1970s. Lead is gone. It was never necessary for 2-strokes, but they were designed for those burn characteristics. Nowadays, you are wise to retard the timing on all motors built back then by at least a couple of degrees. That should help prevent detonation which can quickly destroy pistons. I know that retarding timing on 4-strokes gives you a bit more gut power at low end. Is that true with 2-strokes as well? Naturally you sacrifice a little top end, but you sacrifice the motor entirely if you detonate a piston.

 

[WillyBWright]

Re: Quick Inline Primer

OOPs! Double-posted.

 

[Clams Canino]

Re: Quick Inline Primer

27 was often ill fated EVEN on 70's gas, Mercury changed the sticker to 23 after a season or two. The perfomance gain from 21 - 23 is negligable compared to the risks associated. Remember that 21 degrees is from Mercury not me.<br /><br />These motors are a little "piston happy" as it is, why push it?<br /><br />The only way I'd even *consider* timing one of these things to 27 is if it was on a race boat, propped to make 6500, jetted rich, electric fuel pump, and running CAM-2 racing gas with 40/1 oil mix. And then of course it would get opened up every few races for checkups. And I'd still be nervous... <br /><br />-W<br /><br /><br />

Originally posted by stant1man:<br /> Interesting stuff Clams, i have a 72 1150 and will be setting up the timing just shortly. Do you not gain performance from enhancing the timing from 21 to 23-27? If i set it like you say will that not cost me power and fuel?

 

[kelwendee]

Re: Quick Inline Primer

taking me to school. fantastic boys.

 

[stant1man]

Re: Quick Inline Primer

Its a shame you couldn't get some forged pistons for these motors and you wouldn't need to worry as much. The fuel i run my motor on is rated 98 RON. Does this mean at 21degrees that my 1150 will no longer produce 115hp?<br /><br />What would it produce at say 23??