TOPIC: Yesterdays transom shot

Finally got the Hydrostream running perfect, GPS at 68.2 Thanks to the prop Jim Melanson(g3jim) provided. Here's a shot at about 50, didn't want to turn around and snap a pic after that. Wish I could taek a video like Jim just did.
Randy

No pic Randy. I can see mine and others. User "David K" also had issues with photos on the site. Must be something quirky going on. I noticed some 404 errors when trying to navigate yesterday.

With my camera I just rested it on the seat pointed back to the motor. I also prayed it did not fall over. There were three videos I had taken yesterday but on the middle one I was trying to record the camera fell to the seat bottom and was face up after I got the boat buckin like a bronco merrily goosing the throttle so she would nearly leap out of the water. My birthday was last Friday. I turned 12.

That is a pretty Merc Randy!!

What prop was used on the Hydrostream?

David

Hi David,
Jim had a stock 26 pitch Merc chopper, small ear for an in-line. He had a shortie mid and lower that had this prop on it when he found the set up.
This gave the 68 plus speed at about 6000 RPM, it's easier to read the GPS speed than an exact RPM as the display graduations are not the fine on the tach, the GPS is a digital display. Exact RPM is not critical as long as it is in the neighborhood of 6000 for this motor a WOT.
I tried a stock 24 Chopper both a small ear in-line and a modified V-6 24 Chopper (big ear) that had the blades reduced to inline size, this mod was done by Jim Titusus in FL who raced for Merc in the 70's so he knows this stuff cold and what works. It is not an expensive rework and perf V-6 props are easier to find. Overall the modified 24 ran a bit better than the stock 24 speed wise, stock topped out at about 64 at 6300 RPM, the modified at about 66 same RPM I wanted to back down on the RPM a tad so the 26 pitch was perfect, picked up a few mph as well, I think the 1500 porting starts to run out of breath at about 6300 so best to keep just below there.
I think what I'll do is run the 26 when alone looking for max speed and if I am taking people out for a joy ride I'll swap on the modified 24. Not surprisingly, weight slows the boat along with RPM so a little less pitch will be perfect with people on board. The 1500 is sensitive to detonation and it's best to have it spin up on RPM rather than load it down.
Nice looking in-line you have there, What are you going to run it on? I think the ADI 115 motors are probably the best Merc made in that flavor, smooth, torqey almost the same power as the 1500 but not as fussy. They also have better corrosion protection on the water jackets, better trim/tilt no distributor etc. I wanted to stay correct vintage (74) for the Stream so I stuck with the 74 1500 with all it's foibles. It is a great running motor all that said. I run XS style carbs, no backdraft tubes on the bowls and run the slightly richer .082 XS jets. These carbs were only used on the early 1500 long shafts and all the Shortie and XS's. Lean out is certain death on these. Timing has to be held to 21 degrees total, premium fuel only and I run a water pressure gauge and watch it like religion as a dropp in cooling is also a very good way to ruin one of these. The Stream has a stock transom of 23 inches so even stock, the motor is high. I do notice a drop in pressure at max speed if I over trim, but when the boat is set right where it runs the fastest water pressure remains solid, but worth keeping an eye on.
Randy

Very nice work! Love the boat. As to the carbs used on 1500's I have 3 1500's in the garage a 1973 short 1974 long and a 1975 short and they all have the XS WMK carbs. When did a 1500 start getting the backdraft carbs? I think my 1980 1400 long has the backdraft style carbs.
Conrad

Hi Conrad,
The backdraft tube style came in on 75 on the longshafts. All shorties and XS got the non backdraft. I have a Merc brochure that says these backdraft were used in 75 but at changeover maybe some non B.D. snuck by. At least that's what I can piece together with literature and actual motors of various years.
I think you will find that there are two numbers on the 1500 non back draft carbs, a WMK 1 and WMK 14. The 14's I have seen on the XS with .082's the 1's I have seen on stock L.S. 1500's with 080's. these are the Non B.D. style. I also have a set of WMK 14 with 080 jets but I'm not sure if these were touched at some point. The other carbs I have have not been touched, so I think that is good info. I think the boost tubes are slightly different in orifice size between the WMK 1's and WMK 14's but I cannot say for certain. I do not think Merc gave carbs a different number with jsut a jet size change but maybe they did. In that case the WMk1's and the 14's would be identical except for the main jet size.I just prefer to run the non backdraft as they lean out to save gas, I'm not against saving gas but as you know lean is not a 1500's friend.
A good thing to know is you can still buy main jets for these carbs in all the sizes through a Merc. dealer. I would run the 082's in everything. Once I get my Switzer with XS (similar to your Carlson) all squared away I'm going to try .084's this rev's high and alchohol needs richer jetting, now that fuels are 10% alchohol, I think a slight richening may be in order. The Streams 1500 L.S. definitely runs better with the .082's in up from the original 080's. So I figured I'd try the same on the XS...but that's next year...
Randy

Good info Randy. Ill have to dig into my WMK carbs and see what jets and stamps are on them.

I know my J block 1975 has 82's in it. I have yet to run the other two

You can just disable the backdraft carb correct by closing off the tube correct?

Conrad

Randy, you asked what boat the 1988 115 HP Merc is to be mounted on. I bought a Glastron V-153 new in 1971 with a 80 HP Merc that would do about 44 MPH and replaced it with a 1974 Merc 115 HP in 1987 that increased the speed to 52.9 MPH GPS with a 2-blade cupped 21" Mercury Quicksilver prop. In my quest for speed, I acquired a 1988 115 HP Merc last fall and touched it up cosmetically and will do the motor transfer next spring. The Glastron handles the present motor well and I expect no problem with the increased actual HP on the 88 Merc 115. Plan to raise the motor off the transom about 1" to start and experiment with props. Have the 21" 2-blade bronze (running 5,500 RPM with 74" Merc but with 88' Merc can increase RPM to 5,700 to 5,800),21" and 22" Ballistic stainless steels, a 21" PowerTech RAF, and a 22" small eared Chopper. Hope to reach 55 to 58 MPH.

Thanks for the information on your boat and motor, which I consider the ultimate speed combination.

Hi Conrad,
I meant WMK 11's in that prvious post not WMK 1's sorry about the typo.

David,
That is one gorgeous '88 115!!!
That is the best of the bunch of any and all inline-6s Merc produced. Granted, in stock condition, the earlier 1500xs will outrun it, but other than that it can't be beat IMHO.


Randy,
Thanks for the great write-up on your chopper props results!

Would you please send me contact info on your prop guy via private e-mail?

I'm running .082 mains in my 1500 carbs I installed on my '87 115 when I rebuilt that beast with high domes & 850 4 cyl reed stops.
I need to look and see if mine carbs are back-drafted or not.
I know that if they are that system has been disabled, but if the 11s & 14s are better performing carbs I need to swap out whatever I have installed.
I'm running my beast at 19btdc @ WOT and it runs up to about 6400 with my small ear chopper (sec) 14x22p at 62MPH and doesn't quite reach 6000 with my 14x24p sec @ 64MPH.
I've been tempted to try my 14x26p sec and see what RPM & speed it produces.
I'm running 100LL with AMSoil @ 50:1

Thom, when you go to look for those WMK14's I think you will find I have em . Can,t get that damm Trogs song out of my head now. Its all your fault.

Here is the 1988 115 HP Merc dressed up as a 1974. Midsection piece was not exchanged but could be (reason for the electrical tape over that decal).

David

Great looking motor David, the mid 70s dress code for the mercs is my favorite and how I have my Tinkermerc dressed. Wish I could paint like you! Stunning finish.

On the 1988 Merc, the lower unit was painted 3 coats by an auto body shop, and on the 1974, the cowl and faceplate were painted and clearcoated. All other surface scratches on both motors were touched up by dipping a fine artists brush in Mercury paint and dabbing on, buffing out, and waxing and polishing.