A Question of virginity???

[OldMercsRule]

Re: A Question of virginity???

Hey Jason, I looked over the shroud and the top cover. They looked good enough for me to rap up the old girl and tarp her, and bring them to town in case you want them. The shroud has a few slight ripples in the metal on the port side, (very hard to see unless you look very carefully). The decal and chrome stripes looks fairly good, (a few small scratches here and there); I'm sure this motor never saw salt water. The black paint has a few chips in it and could be lightly sanded and repainted and the result could look nearly new. The inside of the insulation is melted on both sides, (the heat never effected the metal part of the shroud). The top cover also looks good, has some paint chips and could be sanded and painted, but does not have the 1250 decal, (that may be a 1968 vs 1969 issue as I never painted it and there is no indication I could see that there was ever a 1250 decal like my 1969 1000s have on those top covers). The little plastic emblem on the front of the cowel is also broken and 1/3 to 1/2 missing. If you want to swap, (you pay shipping each way): then email me @ and we can agree on the lodgistics of the swap. JR ps: The red line for the 1250 is 5300 not the 5200 I stated from memory: sorry for the goof. Do you gain anything by turning it up to 6000 RPMs, more speed or power?

 

[JasonJ]

Re: A Question of virginity???

Yeah, I think I have to pass for the time being. Not that I don't want to do the swap, but right now I am tied up with dealing with the wife totalling her car, and I don't know how much out of pocket I'll have to part with to get her into another rig. Every penny counts right now.

As far as the max RPM, everybody who knows anything about the inlines have stated that the 1250 not only can safely go to 6000 rpms, but that it should go to 6000 rpms. 5200 is considered lugging the motor and it has been stated that lugging will kill this motor long before high rpms will.

And yes, the power difference between 5200 and 6000 rpms is dramatic. I have played around with props, and that last 800 rpms means several mph. I can't really say I notice much more fuel consumption at those rpms, but I tend to cruise at about 4000 rpms, which gives me about 33 mph and roughly 2.7 mpg. Now that I have the power trim, I can mess with the setup a bit more to see what I can get.

 

[emckelvy]

Re: A Question of virginity???

My old 1350 was a FrankenMerc with a 1250 crank and it regulary saw 6000 & loved it! Wish I'd never sold it but I've got a '72 1400 in the garage awaiting rebuild which should run just as strong. The 1250's did have a bit different rods than subsequent versions of the 99CI-Six, but I've only ever seen one 1250 blow up and I suspect that was due to tinkering, not overrevving!

I rebuilt a 1250 for a guy back in '89 and a couple of years ago he called up and surprised me by saying it was still running strong, just needed a mild tuneup. Good Ole motors, they are!

Cheers...............ed

 

[OldMercsRule]

Re: A Question of virginity???

[quote time=1168132436 user=JasonJ uid=3950 fid=29 tid= rid=41]Yeah, I think I have to pass for the time being. Not that I don't want to do the swap, but right now I am tied up with dealing with the wife totalling her car, and I don't know how much out of pocket I'll have to part with to get her into another rig. Every penny counts right now.

As far as the max RPM, everybody who knows anything about the inlines have stated that the 1250 not only can safely go to 6000 rpms, but that it should go to 6000 rpms. 5200 is considered lugging the motor and it has been stated that lugging will kill this motor long before high rpms will.

And yes, the power difference between 5200 and 6000 rpms is dramatic. I have played around with props, and that last 800 rpms means several mph. I can't really say I notice much more fuel consumption at those rpms, but I tend to cruise at about 4000 rpms, which gives me about 33 mph and roughly 2.7 mpg. Now that I have the power trim, I can mess with the setup a bit more to see what I can get.[/quote]

Hey Jason, Sorry to hear about your wife's car, hope no one was hurt. I can put the sheet metal back on her and if you want to swap some time in the future let me know. Re: 5300 RPM red line, (I corrected my bad memory of 5200 on my last post), do you really think that I was lugging my 1250 at the factory specified red line, (4800-5300 [FYI])????? That sounds a little suspect to me, but I am not a boat mechanic or technition, so I guess Mercury Marine was trying to cause failure by stating that WOT range so people would spend big bucks to rebuild or buy a later model engine when their 1250 laid down due to lugging? Wow! I can assure you my engine did not lug. It was too powerfull for the hull I put most of the hours on the engine, (a lot of hard hours Jason over a 18 year period of time, and never cracked the case), and it would scare anyone but my then 17 year old son to keep her to the wall, (that's how I think he blew a hole in #3). That said: it may have been the cold water he was hotrodding in, (he blew it up on halloween when the lake water temp was quite cold), and WBW has posted cautions about running motors in very cold water, (who knows the engine was 37 years old). When I had the 1250 on a different very light hull I did run it to 5900 RPMs, and it did really fly without problems so maybe you are right about the gains too. How about my two 1969 Merc 1000s? I think I will start a thread about those motors (90 cubic Inchers). JR

 

[JasonJ]

Re: A Question of virginity???

I don't know how the cold water affects the motors. I routinely run mine in water the ranges from 50 degrees to 80 degrees (same lake). I'll tell ya, that motor really perfoms better in the cold water (I think the 30 degree air temp is what makes it perform with the more dense air). I don't know that 5300 is lugging, but it seems close. My motor always hated running wide open at that rpm, it just feels more smooth and not as stressed when at 5800 to 6000.

 

[emckelvy]

Re: A Question of virginity???

Yeah, I'd imagine the 30-deg air temps made it run nice and lean!!!

I recall running my freshly-rebuilt 1350 on a 16' Sidewinder in November on the bay with mid-30's temps. It ran great on the larger .082 jets I installed for "better performance"

Ran like cr*p that summer when temps were in the 70's! So I guess air temps can cause quite a change in equivalent jet sizes, eh? BTW she ran like the blazes with the stock, leaner main jets reinstalled. Lesson learned there, more fuel without an equivalent increase in airflow = no skiing that day!!!