76 OMC 165 4.3 inline 6

[diogee2]

Quick performance question I have been taking the boat out everyweekend and runs fine, I get around 20-25 knots at 3000rpm does this sound about average. its on a 19ft bellboy runs fine I guess I just expected it to go a bit faster for a ski boat. Thanks

 

[WizeOne]

Re: 76 OMC 165 4.3 inline 6

Quick performance question I have been taking the boat out everyweekend and runs fine, I get around 20-25 knots at 3000rpm does this sound about average. its on a 19ft bellboy runs fine I guess I just expected it to go a bit faster for a ski boat. Thanks

Converting that to MPH, I would say that is about right. 19 ft is a bit on the large size for the old 6 cylinder but their are plenty of them around. To go a bit further, however, what rpm and speed do you get at WOT?

 

[ziggy]

Re: 76 OMC 165 4.3 inline 6

so that's about 23-28 mph @3k rpm.
i've got the mercrusier version of that i'd guess. though, i think my chevy 250 is a 4.1L. anyways. starting at about 3k rpm for me, i'm doing maybe 28-29. oddly my tach is about in sync with mph for some reason. for you i think a better question would be what speed are ya getting at wot and are you achieving wot. for my L6 wot spec. is 3900-4300. i get 4300 and am doing 42 mph.. my boats a 19' 75 aristocraft..

19 ft is a bit on the large size for the old 6 cylinder

i dunno. my 19' is rated for max of 165hp which is what i got. i believe it was the largest engine ya could get in my boat at the time...

 

[diogee2]

Re: 76 OMC 165 4.3 inline 6

I will give WOT a check this weekend, the previous owner told me around three is the best efficiency for it and it seems to run really well there so I really havent pushed it to much. We have had it about a month now and taken it out 6 or 7 times. something new seems to break every time nothing big just more annoying, so we are still building our confidence with it. I was just wondering about the prop configuration the original prop I think was in the boat when we bought it and it is beat to hell and I wanna make sure we have the right one on there. The PO didn't seem to be to mechanically inclined from what I have found. Thanks for the info will post what I get this weekend.

 

[WizeOne]

Re: 76 OMC 165 4.3 inline 6

Yabut ziggy, my boat is a midweight '75 x 19'6" and it came with a 190 hp V8. With recent upgrades, I am now easily at 250hp? The stock OMC 190 and the stock Merc 188 had restrictive heads, two bbl carbs and 8:1 compression. 4 bbl versions of those same engines were rated at about 225 hp.

My new motor, in a boat the same size as yours, now has 9:1 compression, a slightly hotter roller cam, better breathing heads and a 4 bbl marine Holley. Easily a 25 hp gain over the stock 302 4bbl. So from that vantage point a 6 cyl, in a 19 ftr, is kinda puny.

 

[ziggy]

Re: 76 OMC 165 4.3 inline 6

So from that vantage point a 6 cyl, in a 19 ftr, is kinda puny.

well, that'd be hard to argue with.... i just keep mine running to oem specs. not much to do to a L6 for hoppin it up in marine use... yer lucky got something to work with...

something new seems to break every time nothing big just more annoying,

that sounds normal....

the original prop I think was in the boat when we bought it and it is beat to hell

a banged up prop will hurt your performance... i don't know if there is a oem prop for any boat. in a merc service manual it'll have a wide range of apps for differnt setups... fwiw. i run a 19p aluminum.
to find out if yer runnin right, yer gonna have to open her up. i think i'd start with a stright prop though and would be worried to open her up with a warbbled one too...

 

[diogee2]

Re: 76 OMC 165 4.3 inline 6

Ziggy, the prop thats on it now is in fine shape I tried to find the stamp on it for dimensions but it was no where to be found. I guess I could measure it by hand but I think I will try WOT and see where that leaves me.

 

[ziggy]

Re: 76 OMC 165 4.3 inline 6

the previous owner told me around three is the best efficiency for it and it seems to run really well there

fwiw. my L6 runs really well in that rpm too. don't know if it's the most efficient. but i'd think somewhere around there would be likely. like you, for a long cruise i'll run 2800-3200 assuming i get the best efficiency there..

I think I will try WOT and see where that leaves me.

that sounds like a good idea. i don't know the wot spec on your omc. i'd think i'd be similar to my mercruiser, but if it were me, i'd wanna read what the omc spec is somewhere..
good that yer running a serviceable prop. that's always a winner. bummer ya can't find a pitch stamp on it somewhere. surely it's on there somewhere... maybe..

 

[diogee2]

Re: 76 OMC 165 4.3 inline 6

Hey just out of curiousity since you guys have similar boats. What kind of trailer set ups do you have. The trailer that came with it is not the original its a newer one and is set up with wobble rollers. It has 4 sets of 4, so 16 total but it is a pain to launch and recover. I have tried to put fresh grease in them but the just seem to be really tough. Some dont lay flush against the hull but I thought that was fine with wobble rollers. and the boat sits kinda high on the trailer so on shallow ramps I actually have to back the truck in the water a litlle which just makes me cringe backing my jeep into salt water. I am just trying to se other setups or see if maybe the rollers are bad or what. I dont want to buy new rollers and have the same problem. I can post pics later if it would help. Thanks Jason

 

[ziggy]

Re: 76 OMC 165 4.3 inline 6

i got a ezloader trailer. i think it's a 75 along with my boat. at least ezloader says they don't support it anymore. at least fender wise.
i got 16 rollers too.
my rollers rolled when i got my boat. so far, all i do is blast them off with some triflow every 3rd or 4th time out. so far they still roll. all rollers contact the hull. perhaps yers needs some modification to get that to occur.

i guess mine must sit high on the trailer too as i can retrieve with the drive all the way down. yes, i found that out inadvertently and got lucky i didn't shorten my skeg.

as far as launch and retrieve go. i put my fenders half underwater and i'm doable. just a push gets it off and i walk it on and winch it up. i did replace my winch on my ezloader though. got a 2 speed w/brake + free wheels. the free wheeling is worth it's weight in gold so the darn handle don't smack ya if ya let it go. the break is nice as i use it to stop the launch and unhook the winch strap after i'm floating. low gear i've not used much...

thats the best pic i got for how my trailer is set up. if ya need another view, let me know..

 

[thompson resto]

Re: 76 OMC 165 4.3 inline 6

fwiw. my L6 runs really well in that rpm too. don't know if it's the most efficient. but i'd think somewhere around there would be likely. like you, for a long cruise i'll run 2800-3200 assuming i get the best efficiency there.. that sounds like a good idea. i don't know the wot spec on your omc. i'd think i'd be similar to my mercruiser, but if it were me, i'd wanna read what the omc spec is somewhere..
good that yer running a serviceable prop. that's always a winner. bummer ya can't find a pitch stamp on it somewhere. surely it's on there somewhere... maybe..

i just looked in my manual and it only lists WOT specs from '81 on, all of which say from 4200-4600 rpm. wish i could say for sure but that is a starting point at least.