TOPIC: long shaft to short shaft

hi all, i have a 1966 merc 500 l/s and would like to put it on my 1961 fleetform. so i'll have to make a s/s out of it. i have a few questons about doing that. i know i'll have to find a 15 inch mid section and drive shaft, will my lower unit work? what years should i be looking for? and is there any other hp engines that the parts will interchange? or do i have to stay with a 50 hp? are there different splines on the drive shaft to crank that i should be aware of before i buy ? iam sorry about all the questons, the area i live in is more omc than merc, so when i find out what i need i'll go to the glassifides. thanks for any info that you guys and gals can give me. frog

1962 was the first thru prop exhaust 500. SO IM guessing 1962 till at least 1967, and possibly more. Im sure the 450, and 350 used the same lower too. You will need: driveshaft, mid, shift shaft, water tube, and possibly shorter exhaust tuner. Keep an eye out because there is probably a short 500 that you could just buy and use as is without all the hassles. If you pull a driveshaft out of the lower unit you have to worry about gear lash and set up.

Conrad

thanks conrad, i'll keep an eye open for a short 500, or maybe a white 400. thanks again. frog

ta-da CLICK HEREhttp://cgi.ebay.com/ebaymotors/MERCURY-OUTBOARD-50-HP-1966-ALL-CONTROLLS-SHORT-SHAFT-_W0QQcmdZViewItemQQhashZitem19c462d474QQitemZ110668993652QQptZBoatQ5fPartsQ5fAccessoriesQ5fGear#ht_500wt_1182

This is a 66 with a 65 center cowl I think. In 1961 you could have purchased a 500 or a 400 I believe for your boat. I have a 1961 500 short, but its my baby.



Conrad

66 500

the link I sent earlier
Conrad

You'll have to remove CLICK HERE from Conrad's link to make it work.
The secret to swapping your '66 500 powerhead onto some other year and vintage will require comparison of the power head to exhaust extension plate (EEP) gasket and either purchasing a shorty mid-housing (drive shaft housing DSH) and it's mating lower unit (L/U).
Having said that, you can use a 650 3 cyl shorty DSH & L/U, or a 70 3 cyl DSH & L/U, or a 500, 50, or classic fifty (45hp) DSH & L/U set-up.
You CAN NOT simply buy a later model 500, 650-3, etc L/U and bolt it up to a '66 500 shorty DSH, or some of the other parts combinations suggested.
The reason is that not too long ofter '66 (not sure exactly when) the bolt pattern (specifically the front starboard and front port studs) were moved creating the need to buy a matching DSH & L/U to avoid nightmares.
I've heard of folks 'egging' out the respective holes for these two studs, but I will not recommend that simply because it puts the driveshaft and crankshaft lower main bearing at risk of misalignment. (voice of experience here)
Note too that the gear ratio in the 650-3 and 700-3 will be different from the original 500 gear ratio and might require prop itch change.
Note too that there were a variety of propshaft sizes and spline counts in these various motors that would require a prop from their parts break-down - not one from a 500.
Having said all that - I have a sweet little '68? Merc 500 mounted on a '77 650-3 DSH with a '77 500 short shaft lower unit bolted up. (see attached photo of the little 'red stripe' 500)
It makes a much nicer set-up simply because the '77 has stainless shafts that will not pit from rust or corrosion like your vintage original 500's steel shafts.
Earlier model stuff - (pre-'65ish) may require replacing your exhaust extension plate (EEP) with the earlier lower pan with built in EEP or some other not-so-easy conversions.
Thom

wow thom, you got my head spinning. i think i'll look for a ss merc , and not do the conversion. i appreciate all the comments and advice, that is why i asked the experts. thanks frog

Y-up,...Nothing more fun than buying a bunch of goodies only to discover they aren't going to fit together, even though they sure looked like they would - right up to that last set of studs.


Thom

Hi Frog . I bought a Merc SS 500 last summer for my boat project .I needed a long shaft but it was a Short ..Dont ask why I didnt ask or check it was one of those days and trip things ....L.O.L..I have to rebuild the transom on my project and was going to cut it down to fit or find a long shaft ..My motor is I think a 1971 ..Im in Wisconsin .

BoBo, hi , send me an e-mail, will you. or a phone # lets talk. This email address is being protected from spambots. You need JavaScript enabled to view it. thanks. frog

email sent