1972 mercury 1400

[buzzm19]

Hi guys, I need some real old guy info. In all my research I can't get a answer on the max timing on this motor, most all the l6's say 19-21 max advance. On this motor the original tag is still on it and it says 27 degrees max timing. On these outboards timing is critical and to me 6-8 degrees is a big issue between running good and bad news. Is there any old timers out there that can shed some light on this. I have been with these outboards for a long time and I know what the original tag looks like on the timing that is put there from the factory and this one is. Thanks Buz

 

[mr 88]

If your going to run gas with a high octane rating,like 94-96 then 27 degrees will be okay. If your running pump gas it is suggested that you back off the timing because of the poor quality of gas today.The timing will not affect your top end,it will affect your acceleration a bit.

 

[buzzm19]

mr 88, back in those days yes there was higher octane gas, this is a bone stock motor and mercury did recomend premium gas meaning 93 octane and I still use it today. I will have to disagree with you about the timing. Timing is a major factor and not too much at idol but as rpms increase the spark has to occure earlier to compensate for the speed of the motor since spark speed does not change. The higher the rpms the more critical the timing. But my question was why does the oem tag say 27 degrees? If yes the gas is not what it used to be I can see a retard of a couple degrees but not as much as 6 degrees. Thanks Buz

 

[merc850]

A lot of information has been debated about the octane needs of Mercury outboards; it says in the owner's manual "regular automotive gasoline" - this is from the manual
personally I use regular fuel.

 

[emckelvy]

Use of regular fuel may be the mfr's current recommendation. However, later model Inlines came with "low-dome" pistons which lowered the compression ratio. Along with a number of other design changes which reduced the chances of destructive detonation. A 1400, unless it has been rebuilt and the pistons replaced, has hi-dome pistons which are less tolerant of low-octane fuels.

One big issue on distributor-fired inlines is that #3 cylinder tends to be the one that runs hottest/leanest and usually has more timing "lead" than the other cylinders.

Thus the recommendation to reduce max spark advance from the old factory specs. The accepted "link and synch" settings nowadays are maybe a bit conservative at 18-20 deg BTDC, but they do keep the engines from burning up!

I'll pretty much guarantee that if you run that 1400 at 27 deg max advance and use regular unleaded, it's likely to fry a piston!

If you're looking to wring the last bit of performance out of the ol' Tower of Power, you're better off running the highest-octane premium you can find, or stepping up to Avgas 100 LL (Low Lead). The old Beasts run pretty good on that stuff, and you might be safe to run a higher spark advance. At your own risk, of course!

I'd definitely be keeping the impeller fresh and install a water pressure gage to monitor cooling system condition. And keeping a good eye on spark plug condition. First sign of detonation (and pretty much your only warning of imminent destruction) is bits of congealed aluminum on the end of the spark plug. Guess where that is coming from!

Last caveat, you CANNOT overprop these motors and expect them to live. You must prop them to run (at minimum) at the upper end of the mfr's WOT rpm recommendations. Which for a 1400 should be something like 5500 as I recall. Won't hurt it to spin a bit faster, either.

If you install too-large a prop, the engine will be "lugging" and this promotes destructive detonation.

I had a 1350 on my old Sidewinder and it was a screamer. The most significant difference between the '72 1400 and my 1350 is the 1400 had the newer-design split-port exhaust tuner plate, which I imagine scavenged a bit better than the old-style plate. Thus the 5hp difference, or maybe it was just Merc playing with the numbers! With the right prop, the 1350 had a killer hole shot, good top end and would spin right up to 6000 if needed.

The 1400 on a light hull, properly set up, with a decent prop, is an excellent performer. Amongst the Inline Sixes, only rivaled by 1500's and later power-ported models.

Anyway, hope that helps with a little background on these great old motors..........ed

 

[Faztbullet]

If every thing is in good shape and sync/link/belt timings are correct it will run fine on 89octane at 23 degrees max timing,

 

[buzzm19]

Thank you, finally I am getting some serious answers, Emckely is right on the exhaust (I am re doing a 71 1350 and this 1400 has different exhaust as I saw by the gaskets) and yes the 1350 has one hexxa hole shot as I use to ski behind them (giving away my age) when they went you had two choices get up or let go thats it. 23 degrees on 89 octain is for me ball park and I only run 93. Fazbullet also thanks. I think merc changed around some either porting, exhaust and some other things and thats why I see most newer mercs at 21 degrees max (I also ran a 78 115 and it was a bear out of the hole). So I know the 1400 is an odd ball, even though my 1350-1400-115 had the same pistons. I could go on and on about these motors as I love them. Fastbullet, that 13ft allison must be outragus I had the 115 on a 70 14ft glastron and I thought it was bad ass, crack the throddle and I would see sky. Thanks Buz

 

[emckelvy]

Buz............both the 1350 and 1400 had huge intake & exhaust ports, almost like a 1500, except they didn't have the power-ported pistons & special passages built into the blocks.

Funny thing was, the early 1150's had same ports but the reed stops were teeny weeny to restrict the top end, and very large venturis were installed in the carbs to further restrict airflow.

Then there was the '79-or-so 90hp that had itty bitty ports, didn't breathe worth beans above 5000 rpm, but had excellent low-end torque and outstanding fuel economy. I recall testing one of those on a Boston Whaler and she lept right out of the hole, just ran out of steam at higher speeds.

A Merc for all seasons I reckon. Amazing what they did with a 99-cubic inch engine!

I remember how much fun we had back in the 80's with cheap motors and really cheap, good-quality gas. I had a '64 100hp Tower of Power on a 14' Fiberform, I'd imagine that your 115 on a Glastron would have whipped it pretty good! It did OK for 90 cubes, though!

Cheers........ed

 

[buzzm19]

Thanks guys for all your help, its really hard to get info on these older motors as there are only a few old timers left from this era. If any one is interested about building or rehabbing these motors the answer is yes you can pull the crank without pulling the pistons so if you need to address only one pistion you can do it with out pulling the whole assembly. Since I wanted to check all the pistons I pulled them seperatly, I had the ring compressors and put each pistion in seperately which is better than playing with the whole assembly and less chance of a mistake. On the rod bearings I used vasoline petrolemen jelly and that worked great also. It always seems that all you good guys are alwayse so far away, I take my boats on the delaware river north of Phila. Thanks again Buz

 

[emckelvy]

Hey, Buz............I've used many jars of Vaseline as well, putthing powerheads back together! OMC sells a tube of needle bearing grease which I like because it's a bit "stiffer" than Vaseline and comes in an easy-to-apply tube. P/N 0378642, around $6. Last engine I rebuilt was a 115hp V4 and I used the stuff, it worked out really nice.

My good buddy Doc Frankenmerc has a dandy set of ring compressors; I never did have any, and developed my own way of getting the pistons in, by hanging the crankshaft on a ratchet winch then lowering into the block. Got to where I rarely broke a ring! But the compressors do work slick once you get used to them.....ed