Information or part wanted.

[Fastfrank]

I am making a Mark 55 H clone. I have an older hydro short unit that I want to mate to the 55 power head. It appears that I need a one fourth inch spacer plate between the block and the mid leg. What is the part number for this plate or can you tell me who makes it? The phone number for Bass Machine is disconnected. Your help will be greatly appreciated.
Frank

[Bob Rusnak]

From what I know there is no spacer plate made by Mercury to do this. I have made them from a cut down MK 55 lower cowl. I think I may have on here. If you can't come up with one give me a PM and I will see what I have....

[dwhitford]

I think Bob is correct in that the lower cowl provides the quarter inch of spacer that you need.

[Fastfrank]

Thanks Bob and D Whitford. Yes It appears that I only need to cut off about 2 inches of the female receptical of the water pickup on the bottom cowl and then pray that the water can make it to the block.
Thanks again.
Good times ahead.

[DeanFHobart]

Just a suggestion........ I would not do something in which you have to pray to get the water into the block.... I would get in touch with Weinant, (that is the last name) first name Mike... his company used to be or still is Trident. Someone here will have his contact information. Post a new question here asking for his contact information.

Good luck on your project.

[DeanFHobart]

As luck would have it I was looking at BoatRacingFacts.com and Mike Wienandt posted there on fitting pistons. His company is Wienandt Performance Technology. He is in Wisconsin.... phone number... 920-574-2219. His web site is: wptracing.com.

He will know exactly how to make an adapter plate for your application. Do yourself a favor and get in touch with him.

[Bangarang]

Hey frank it sounds like you have a Q shaft instead of a H shaft

[Yellowjacket]

Early model Merc 500's and the Mark 55 powerheads don't use the exhaust extension plate that is used on the later motors. The powerhead clamps the lower cowl between the tower and the powerhead. Later model Merc 500's have a exhaust extension plate that is used between the tower and the powerhead, and the exhaust extension tube needs to be cut back before it fits the racing tower. But the bolt pattern for those later model motors is different than the earlier powerheads and they won't bolt up to a real 55H tower. The two aft bolts on the later powerheads are further aft and don't line up with the holes on the earlier 55H tower. If you have a real 55H tower you need the earlier (before 1965) powerhead and you use the lower pan and you should be fine. There are some Merc 402XS or 35SS towers that have both bolt patterns. You can bolt up either powerhead to those towers, but to have the proper spacing the earlier powerheads need to use the lower pan so that the driveshaft spacing is correct. Later model powerheads if you bolt to that tower you need the exhausts extension plate and cut back the extension tube to fit in the tower. The cooling water tubes from the corresponding Merc 500 can be shortened to be used with the H tower.