TOPIC: Weird powerhead ? No idea what this is......again!

Hey,

Today i picked up a merc 1500 {for parts } motor and during the conversation about vintage Mercury race motors the seller told me there was an old Mercury powerhead lurking around somewere in the shop. I asked: is it a small or big motor? Seller answered: Not a complete motor an if i remember well it has 6 cilinders in line and 6 carburaters and a weird home brew bottom cowl and top cowl. Long story short. He found the motor and I bought it.

At first i thought it was a Twister but I never saw this kind of carburaters on a Twister. There is no serial number so I hope someone can tell from the pictures what it is.

Taco

photo 2

photo3

1250 BP ?????

hey Dave,

I searched google and found a bit similar picture like mine but with the normal carbs. The cowl was almost the same made of one piece. They spoke about a 1250 super BP. Most likely my motor is a standard 1250 or 1250 BP tuned by Walther Vieser as the seller also owed one of his race boats.

Very AWESOME purchase Taco!!!!
What you have there is an early Twister 2.
I've heard that those carburetors reportedly didn't perform as well as the next style Tillotson carburetors, but I have not had any hands on experience with the early carburetors.
I would like to see a picture of the bottom of the block.
It might be a "C-6" 1350 based race motor, but again I have no expertise on the C-6.
The (2) pieces I don't have are the fiberglass drop-over engine cover and related lower pan. I've had a chance or two to purchase them, but I just can't convince myself to part with the huge pile of my Mercury Money that they sell for.
Doc F

I have attached a couple pictures of a 1250 BP, which is built from a 1250 with 3 carburetors.
I can't find my pictures of a 1250 Super BP, but it is a unique block, a 1350 with unique porting and 1250 fuel pump blocks, and just (3) carburetors.
I also attached a picture of a C-6 Mercury race motor, also based off a 1350, but has (6) carburetors.
doc
1250 BP

1250 BP

C-6

Hello Doc,

I think that after reading your posting and the attachements things come together. Mr Vieser had direct access to mercury racing engines from the Belgium Mercury department. He has set many world speed records and after his passing his doughter sold almost all of his boats with motors, props and record documents and trophys. A few weeks ago a friend in Germany bought a car full of brand new racing equipment including 2 brand new { no serial numbers } 650XS or 700X powerheads and at least 10 new carbureters for it. Lots of pistons etc, etc.

I enclose more pictures for you to decide what motor it is. From your pics the C-6 looks most like mine. The bottom cowl and hood may be original but looks like home made. What is in the pics is the only things i have. No midsection etc.

Taco.

pic

pic

pic

This morning i had a closer look to the motor and found some numbers that may be usefull.

The bottom of the motor is the same as a 1350 powerhead and slightly different than a 1250 head. { I have both for parts}

There is a kind of plastic strap that holds an ignition cable with a number. M or N? 325281 -7

The carburetors are numbered 1 to 6 but number 5 is on the second cil from top. From top to bottom the carb. numbers are A3J, A6D, A2A, A1A, A6A, A2H

I cleaned the hood a bit and it looks very vintage to me. To give an idea of the hood`s size: it slides over a Merc 1500 with the complete upper cowl, cowl and front on it!! It`s BIG!!

With the pictures of doc Frankenmerc i think { for now } the motor is a Twister II-X.
Taco.

Hi Taco,
Definitely not a T2x.
The T2x has the later design exhaust - like a 1500.

I'm pretty sure you have the 1350 based C-6.
The very large drop-over motor cover was made by Mercury Racing specifically for the big 6 carburetor inline-6, like the C-6, T2, and T2x.
It looks like it may be NOS, and never had decals put on it.
Very cool pieces of Mercury Racing History.
I am very jealous!!

doc

Hello Doc,

Thanks for the nice pictures and your support to help to identify the motor. When I started the topic i had no idea if it was a real twister, and if, a "rare" motor. The picture of the C6 in black/white has the same carburetors and air intakes? like mine.

The hood has some damage as the block was inside the hood thrown into a container. Some "junk" on top of that but at least it is there! Looks like it never had decals and also never had the metal parts to connect the hood to the bottom cowl.

No reason to be jealous because you have the most beautiful Mercs I have ever seen.

Thanks, Taco.

Found some more info on "boatracingfacts" . Someone talked about a 1400 base motor with Ted Morgan carbs.

"The C6 made it's first appearance in Berlin in 1970. It was used sporatically during 1971. Sometimes it ran with a single pipe exhaust system, sometimes a two pipe system and usually with a closed system. The C6 was the 1400 block with six rectangular carbs. They were referred to as Morgan carbs, named after the engineer responsible for it's development. It got better and better, won first single finishing fourth overall at Havasu, and all team boats were running it at the beginning of 1972.

As good as the C6 ran, the carbs remained a problem as they were very tempermental. Utimately a six Tillotson carb system replaced the Morgan carbs in 1973. The 1400 block received some porting changes and the TII was next in line to be made available to the racing public in 1974."

Taco.

You might want to search www.screamandfly.com as there are a number of discussions with info on the "Ted Morgan" carbs, as well as the "1400" engine. Seems the "Morgan" carbs were used in development only and never saw official production to the consumer. Sounds pretty rare to me!

I've attached a pic from one discussion I found. Wouldn't it be cool to have some custom "repop" decals made up for when you restore your "1400"! It'd be a mind-blower!

It's hard to say what went on behind closed doors in Mercury Racing development, but the first 1400 sold to the public was 1972.
I suspect that the newly configured exhaust of the 1400, was probably developed long before it was introduced and sold to the public.
The picture of the bottom of Taco's block suggests it began life as a1350 - not a 1400.
The Twister II, and Twister II-x were both built with uniquely ported 1400 blocks.
doc

Hi Doc,
On the screemandfly forum i found and contacted "Willabee" his name is Bill and told him about my powerhead and the info you had on it.

He answered with: "I was the foreman of the Merc Racing Team when the C6 came into play. I was around them until they finally evolved into the Twister II."

After he got some pictures his response was: " Wow, i had never thought to see one of this motors again. You sure have bought a C6.

Then he asked me to search for a serial number and he told in what place to look for that number and i found it.

A few minutes ago I noticed the next info on S and Fly :Taco, you found the one I was hoping might be there! The B.3871040.T. tells me it was originally built at Merc Racing in Oshkosh which was designated Plant #38, in 1971 and was the 40th to be built there!

Mistery solved

Yep defiantly a C6.

I assume this had a standard firing order....... Or did it have the newer crank and t2/t2x firing order???? What do you think Thom?

Conrad

The firing order of the C6 is 1-4-5-2-3-6. The block looks identical to the 1350. I also bought a powerhead with serial number 2538553 from the same guy that has "typhoon" marked on the cranckcase. Any idea what HP this one is?

I noticed a small difference in 2 850XS LWPU`s. The one i put on the 1500 J block has 2 small water inlet holes at each side of the gearcase. Sunday i bought an 850XS that has 3 holes at each side. Is it possible that one is a 1500XS LWPU?

Taco

Typhoon was only on the 1250 block. 1968-69

The 3 hole case is older is all. Later they blocked off one hole and made it 2 holes per side, supposidly making the casting stronger. The 2 hole will usually look like a 3 hole only cast shut in the 3rd hole position.

1500xs/850xs cases look the same no matter if its a 2 or 3 hole version. The differences are internally.

To complete that C-6 you need to find a Super BP mid and put it on there. Would be a nice piece.

C

Hey Conrad, You`re right. The LWPU looks like your describtion with the lower cast shut.

Saturday I ran my French build boat { Ken Basset Rascal } with the J block for the first time. As I do not have a tachometer yet I did not went full throttle. With the short shaft block on a long shaft transom and a 22P chopper it made an easy 55mls on an airguide seaspeed contralog { 80 mph } speedometer.

It will probably be impossible to find a Super BP mid over here and even if i find one it will end as a display/ conversation piece. For display only it may probably fit on a standard 1350 mid.
Taco.

Taco,
To determine if your LWPU is originally from an 850xs or a 1500xs, determine the gear ratio.
The 850xs will be 2.31:1 and the 1500xs will be 2:1
To check ratio:
Shift the unit into Forward gear and rotate the drive shaft clockwise.
Once the prop shaft begins to turn with the drive shaft, stop and mark the prop shaft and the gear housing near the prop shaft.
Then mark the driveshaft and the water pump housing.
Then begin rotating the driveshaft clockwise, counting the number of rotations required for when the prop shaft again lines up with the mark on the gear housing.
If the drive shaft makes two exact revolutions before the prop shaft again lines up with the mark on the gear housing - you have a 2:1 ratio.
If the drive shaft makes two and 1/3rd revolutions before the prop shaft again lines up with the mark on the gear housing - you have a 2.31:1 ratio.
Since it is probably old racing stuff, it is always possible that you might find the ratio is 1.78:1
If the drive shaft makes one and 3/4 revolutions before the prop shaft again lines up with the mark on the gear housing - you have a 1.78:1 ratio.

doc

Thanks for the info Doc. The 2 LWPU`s I have are from standard 850XS motors and were not part of the deal with the C6 powerhead. I will check the ratio like you described. I have a LWPU of one 850XS on the Merc 1500 j block. Would it make much difference if it was a 1500 XS ratio LWPU ? Some people told me that when i hit the throttle the motor with the 22 P chopper should make a lot RPM before it "bites" the water and "take off" . In fact this happened only for 2 seconds with some water spray and than it gets off. I was actually very overwhelmed by the power of this motor. The acceleration from around 30 mls to full power is incredible. Or it has to do with the fact that i was used to the Mark 78 and Merc 1000 1963 and 1965 only.

Next time i will check the speed with GPS as the speedometer may not be reliable { it`s old } The other boats on the 3 mls race track did not even come close to my boat.
Taco.

I for some reason was thinking the LWPU gear cases were empty. If they are complete then yes do as Thom says and spin them and figure out what the gear ratio is.

If your boat is only capable of 65 mph or less either ratio will work finding props. If your going to be running 65 70 or 80 mph the taller 1500xs ratio is favorable. A 30 pitch prop will max out around 68 mph using the 850xs 2.3 ratio.

C