4 blade vs 3 blade torque

[QBhoy]

What you said is right out of the Mercury service manual (the one I quoted a few days ago covering my 115 carbed). In the front are detailed explanations concerning using and maintaining your new engine. Trim tab is specifically mentioned with respect to trim positions and it clearly states that at mid trim positions, tab is neutral....for high trim positions (with right hand turning props which this engine turns) it has to be set to the left (Port) to offset the torque and for negative trim positions it's just the opposite. It goes on to say, what we well know in that the higher the AV plate is mounted, the less the effect of the tab.

My current boat has that personified: The PO, as it's proving to me, not somebody swapping parts at the dealership, had a 22P Ballistic SS, engine jacked up in the 4th (highest mounting position) hole and the TT was centered.

When I was dropping my engine I noticed that at high trim positions, the Port steering tendencies got heavier and I had to put the tab as far as it would go to the left after I got to the last hole )engine sitting on the transom), which helped but still had a good (undesired) feedback at higher rpms. Course the more you compensate for that the worse the negative trim right feedback. I had a Teleflex no feedback steering in my last boat. Don't know what's in this one, but being a Crestliner I would expect it to be no feedback.

Good read. What bit of what I said is out the manual ? You mean about the tab ? I should try a cut down one, but ultimately I think o need proper steering

 

[jimmbo]

From 1960 - 1969 all of OMC V4s, with the exception of the 100HP, used as 23:20 gearcase. These V4s actually used Props that had smaller Diameters(10", 10 1/8", 10 1/4" and one with 9 1/2") than those used by the 28, 33, and 40 HP(10 1/2", 10 3/4", and 11") engines OMC made during the same Era. Mercury used higher gear reduction(usually, but not always, 2:1) during the 60s on their Inline 6s, and Mercs had a reputation for pushing a boat faster for a given HP than the OMCs

 

[jimmbo]

Good read. What bit of what I said is out the manual ? You mean about the tab ? I should try a cut down one, but ultimately I think o need proper steering

Merc makes several Trim Tabs that offer clearance for some of the Higher Performance Props. Some people just cut away material on the Stock Tab.

 

[jimmbo]

From 1960 - 1969 all of OMC V4s, with the exception of the 100HP, used as 23:20 gearcase. These V4s actually used Props that had smaller Diameters(10", 10 1/8", 10 1/4" and one with 9 1/2") than those used by the 28, 33, and 40 HP(10 1/2", 10 3/4", and 11") engines OMC made during the same Era. Mercury used higher gear reduction(usually, but not always, 2:1) during the 60s on their Inline 6s, and Mercs had a reputation for pushing a boat faster for a given HP than the OMCs

Damn... It should be ' From 1960 - 1968, not 1969.

 

[dingbat]

From 1960 - 1969 all of OMC V4s, with the exception of the 100HP, used as 23:20 gearcase. These V4s actually used Props that had smaller Diameters(10", 10 1/8", 10 1/4" and one with 9 1/2") than those used by the 28, 33, and 40 HP(10 1/2", 10 3/4", and 11") engines OMC made during the same Era. Mercury used higher gear reduction(usually, but not always, 2:1) during the 60s on their Inline 6s, and Mercs had a reputation for pushing a boat faster for a given HP than the OMCs

Makes sense as long as its a foot race. Not so much when it comes to tug a war.

 

[jimmbo]

Makes sense as long as its a foot race. Not so much when it comes to tug a war.

I wouldn't say that, When OMCs 70.7 cubic inch V4 was placed in a Tug of War with Mercs 60 cubic inch inline 6, the Merc pulled it backwards. Source: Iron Fist, the Many Lives of Carl Kiekhaefer

 

[Fed]

The copyright is on the website. No credit on the article.

Please explain how the figures 8-24 and 8-26 are incorrect

Point taken on the copyright dingbat but I still think it's a ripoff.
Counter rotating props, that will never work.

 

[Texasmark]

On the small, fast turning props mentioned herein, I was there and OMC just didn't have it. Their LUs of the era large and small engines, just sucked. (Opinion from a several engine owner). That all changed at the end of the 1960's when they followed Mercury's designs (opinion) and designed a decent LU outcropping of the 3 cyl midrange looper, (opinion) and while they were at it, they added some trinkets to the V 4s making them more fuel efficient; tuned exhaust, back drag carbs, swinging a 13" prop at 2:1, streamlined gearbox.

I bought a 125 Johnson new in 1972 and an 18' bow rider, tri hull Caravelle. Regardless of the boat, many times I tried to catch Mercury 125 "Towers" of the era and couldn't do it. OMC did do a good job on fuel efficiency and reliability, I'll give them that over the efficiency of the gas guzzling earlier engines. (opinion) I had the boat about 7 years or so, went boating usually more than once a week and other than tearing up aluminum props...till they came out with the SST, a had to have at $185 back in 1973, I had zero problems with that engine, electric shift and all, ...a real sweetie.

 

[JimS123]

I was never a speed freak. So, whether a Merc was faster or not it was of no concern. IMHO, Rudes and Johnys just ran smoother and quieter so that's what I bought. Mercs were a PITA to tune and repair (thanks to their owner) so only a few diehards bought them.

However, in later years what I read (maybe true maybe not) was that Mercury actually cheated and their competitive models actually had more HP that the competition. Could that be why Mercs were so fast? I dunno.

Al I DO know it that in recent years I have been a convert and now all my 4-strokes are Mercs.

 

[Texasmark]

IMHO, Rudes and Johnys just ran smoother and quieter so that's what I bought. Mercs were a PITA to tune and repair (thanks to their owner) so only a few diehards bought them.

However, in later years what I read (maybe true maybe not) was that Mercury actually cheated and their competitive models actually had more HP that the competition. Could that be why Mercs were so fast? I dunno.

Agree with you on Mercs in the shop. Back when I was a teen and getting into boating, '55-'56 time line, the Merc dealer always had engines all over the place to fix...saw it, was there, and formed that opinion back then! Saying back then was it's yours on the weekend and on Monday it belongs to the dealer's service dept. or something like that.

Don't recall any association with a Johnny-rude repair shop. I had an 18 rude at the time I bought new and never did/had to do anything to it, nor visited one of their repair facilities. My running buddies (and their dads) ran OMC also and never talked about problems.

On "cheating" or producing engines sure to meet the spec, I have heard/read that too. Also I don't recall Merc ratings initially (Brake HP?) or later on in '85 time line (heresy) switching to prop ratings.

 

[JimS123]

Agree with you on Mercs in the shop. Back when I was a teen and getting into boating, '55-'56 time line, the Merc dealer always had engines all over the place to fix...saw it, was there, and formed that opinion back then! Saying back then was it's yours on the weekend and on Monday it belongs to the dealer's service dept. or something like that.

Don't recall any association with a Johnny-rude repair shop. I had an 18 rude at the time I bought new and never did/had to do anything to it, nor visited one of their repair facilities. My running buddies (and their dads) ran OMC also and never talked about problems.

On "cheating" or producing engines sure to meet the spec, I have heard/read that too. Also I don't recall Merc ratings initially (Brake HP?) or later on in '85 time line (heresy) switching to prop ratings.

If you want to get there fast, buy a Mercury.

If you want to get back, buy an Evinrude...