TOPIC: 1961 Merc 700 Dir. Rev.

Got this on a boat this weekend.
Compression was real low on 1,3,5,6. 109 thru 118
Helicoiled on 2 and 4. I did not get the readings.
No faceplate.
It is a shorty though. Parts, parts.
I'm a sucker for the 6's.
This can't be even close!!
Now heres a pair to draw to.
Neil

Another nice score Neil, you're getting quite the collection there. You know those compression readings might come up a bit after getting the rings freed up. (I'm the eternal optimist, ya know.)

I've seen the timing marks run like that before. My 700FGS wouldn't run with them set per the manual. After refreshing the wiring harness, replacing the broken timing belt, and rebuilding the fuel system I couldn't get her to do much more than cough and sputter. Moved the belt one tooth (advanced ?)on the distributor gear like your pic shows, and she fired off and ran like a new one. Only thing my "Merc advisor" and I could figure was someone replaced the plug wires, and got them one hole off in the cap?

Anyway, don't give up on the old girl and part her out 'till you give her a chance. SWEET motor.

Thanks Mark
Words of encouragement for sure.
I have got alot of things going in my one man shop.
This old girl will have to hang out on the stand for awhile.
My general once over is not by any means all conclusive. But there were a couple of issues. I gotta quit gathering and get back to my 1000 soon. But those good deals just keep popping up.
The little boat that this motor came on is going to be pushed around this summer by my Mark 55. The boat is a 14 footer, so it should do just fine. Both boat and motor are just cute little shavers.
Neil

Timing mark, a cast in arrow, is on the pulley itself not the pulley cover. That looks like a home grown cover too, at least I've never seen one like that and I've seen a LOT of 6's.
For parts interchange the lower unit on the 700 is different than on the Mark 78. It is based on the FGS lower and has larger shafts and different props. It should also be noted that the crank spline where the drive shaft engages is different, at least that's what I have come to understand. The spline on the 700 is much larger (same as the FGS) than on the 78 so power heads although nearly identical will not interchange.
You could make a 78 shorty but the driveshaft on your L.S.78 lower would need to be swapped out with a shorty or shortened. There is a shop in FL that can shorten the drive shaft if you remove it.
Not sure what your plans are but if it is making a shorty 78 if the L.S. drive shaft is good, most aren't, then have it shortened it might be easier than finding a good short version.
Also know that long shaft D.R. motors are rare.
Good luck, it looks like you have caught the illness we all suffer from!
FYI I have a 700 DR faceplate for that motor. It would need a re- chrome and an emblem to be mint but it is clean with no damage.
Randy

Agreed the timing mark ( arrow ) is not on the cover plate. It is on the pulley.

the cover is not home grown it is merc correct.

All the 60 & 66 cube DR cranks are the same. I have 700 powerheads on two Mk 75's I've done.

Jim S,
Not arguing, just a different DR questions for the DR Master.
Isn't the 800DR the only DR with a larger driveshaft?
And isn't the 700FGS the only 700 (66 ci) with a larger driveshaft?
I see that I have a 600DR 'donation' on the floor here, but I'm too messed up to roll it around to see what it is. Is it a Marathon Six like the Mk75?

Like everyone says - remove the cover of the pulley (part with the timing lines on it) and you will see the raised cast arrow on the pulley. The arrow needs to point at the center of the crankshaft when the line on the flywheel is pointed at the center of the distributor pulley.
On some Mercs there is also a TDC line stamped into the flywheel with a '0' stamp on the line. In that case the line with the 0 will align with one of those lines on the distributor pulley cover plate when the crank is TDC #1. Completely different from the line stamped into the flywheel that marks where the arrow and this mark are required to be to set the distributor pulley in sinc with the crankshaft.
If the cover plate being used is properly positioned on a matching distributor pulley those (2) holes will go on two matching raised circles for proper alignment of the TDC marks.
There are a variety of different distributor drive pulleys and related cover plates.
Thom

Well it's nice to learn something. The thru hub DR unit I looked at must have been from an 800 because it was the larger drive shaft. That must be an unusual driveshaft in the 61 700 DR to marry the small top splines on the crank and also fit with the waterpump layout of the later thru hub units, sounds like unobtanium if you need anotherone! a one year only arrangement. 62 was FGS then replaced by the 650 4. I have both 66 cube 78's and 700's but the 700's are from FGS so no swapping.
Thanks Dave indicating the pulley cover is stock Merc, I've had maybe 30 in line 6's from the late 50's early 60's and never saw one like that..just goes to show.
Keep the good Merc info coming! This is when the site works well to benefit we who work the motors!
Randy

Hi Thom,
The 600 is a 60 cu in block, like the former Mark 75.
Randy

Neil,
You are the Man, another great find! I'm humbled and jealous at the same time.

Bob

Bob
I am but a tadpole.
But I am growing!
Neil

Randy
I am interested in the faceplate.
Could you e-mail me with the details?
Neil

Correct Thom, the larger spline drive shaft started with the 700 FGS & the '60-'61 800 DR, serial numbers 1335465 - 1379805 ( this was the start of this configuration that Merc used for years ). The 800 is a 70 something cube motor. The 600 is a 66 cube Super Marathon decarbed motor, they used the smaller carbs and reed blocks, with corresponding crankcase cover. ALL the 60 & 66 cube DR motors use the same shaft spline, INCLUDING the 700 DR. Hope you guys find this info helpful.

JS

700 DR powerhead on a MK75..........

JS
Thanks for the info.
Great video, did you go after the Evinrude?
Neil

Neil wrote:

JS
Thanks for the info.
Great video, did you go after the Evinrude?
Neil

You're welcome Neil!

Was a buddy of mine, it was his way of getting back at me from trying to keep up with me all day. We started even and I had to circle back........over & over!

Some more info I forgot. The 60 cube Marathon Six was only produced in '57 & '58. They went stickly to the Super Marathon in 1959. To keep producing 60hp motors, they detuned the 66 cube Super Marathon as stated before. 1959 was the MK 75A ( 66 cubes detuned ), 1960 was the same version, just called the Merc 600.

Thanks again JS.

The 800 DR can be made into a 90cube or 99 cube DR if needed. IT shares the same spline driveshaft as the rest of the Inline 6's. The 1350 is the largest I believe that will work. After that they changed the exhaust cavity.

Thom there was that guy on the G-3 forum that had the 1250 on top of a 800DR tower/lower.

The 60 and 66 DR power heads share the same splines as the 4 bangers. MK 55's Merc 500's etc. Ive heard people putting an early 60 or 66 power head on a MK 55 tower/lower, with modifications to make a frankenmerc.

There was a special block shown on the Johns Merc page. They made 60 cubic inch replacement blocks later than 1958 as re-sleaved 66 cube motors it is thought. LINK: www.pfs-ware.com/phpBB3/viewtopic.php?f=12&t=3888
Conrad

So that is what happens when you rely on an old memory. The 600 DR is indeed a 66 cu in. I was remembering Mk 75 is 60 cu in and 60 h.p. so thinking 600 was similar. Me bad.
Just to square things in my mind I looked it all up the Mk 75 of 57 and 58 had 60 (actually just under) cu in. all other non 800 DR where 66 cu in. But I guess most of you knew that!
Randy

No worries Randy. Out of all the dockbusters the 600 is the most odd duck of them all. Its a leftover product that was re-badged. All it is, is a MK 75a with MERC 600 stamped on the front. The last true 60 cube motor was the 1958 MK 75. But replacement blocks later could be found.

All the other motors that year went to the newer thru prop exhaust.


I either see MK 75's, MK 78's or 700's around here. Very few 600's or 800's/

Conrad