MERCURY MARK 55 PISTONS

[jeff-register]

Lab guy,

I used to get seals by size from State Seal.com here in Phoenix Az fpr my Firestone (Scott Atwater) motors.  The problem with the Mercury seal is it’s threaded into the lower unit. the threads for a mk 25 & a KH7 are the same but the threaded hex collar that is molded ino the seal (brass) the hex head to tighten to the lower unit is wider on the mk 25 & will not fit into the KH7 leg without grinding material from the KH7 leg. Mercury must of made the seal collor hex bigger as a upgrade. The threaded seal swaps either way except the KH7 ; is thinner in the lower leg. Also The KH7 had overheating problems & Mercury had a revision waterpump assembly’s to correct this free of charge. I’m not sure if my motor made it back for this revision. The Mark 25 had a much better waterpump & stronger bearings, shafts & gears. All I need is a new KH7 shift shaft seal to complete the upgrade. I’ve tried Joe Pool too, My KH7 is such low hours the pull rope is still white with the red line on the rope. It sat in a dealership on display for many years before I bought. Yes I gave too much $1000.00 for it but it’s like brand new & don’t want to grind the leg. P.S. I couldn’t afford this motor now I’m retired.

Thanks for the  input,

Jeff

[jeff-register]

Lag guy,

The shift shaft seal isn’t friction fit, it’s a threaded brass collar with the seal imbedded into the brass so it must be a mercury part as far as I know.

Anyone know where I can get a new one?

[jay]

thanks for all of your help, for now I found a better block, but if any one finds oversized pistons please let me know.

 

Jay

[modhydro]

I talked to Alan at Aeroliner Boats and they have oversized pistons new in the box from Wiseco. Piston, rings, wrist pin and circlips all for $148 each…..

[jeff-register]

Wow have things changed! I can remember buying pistons for a 1965 Ford from the dealer & I paid $25.00 each but no rings. Same for a Mersaties Benz 6 cylinder diesel. They wanted $200 each without pins clips or rings. Reminds me of a hospital bill. I was charged $175.00 for “self help” as it showed on the invoice. Banks are crashing again like in the depression again, BAD SIGN!!!! Enough out of me.

Good luck with your Mark 55 project & keep trying you will enjoy very soon!!

Jeff

[Tubs]

I don’t know what year you were buying those $25.00 pistons for your
1965 Ford but- $25 in 1975 is equivalent in purchasing power to about
$140.26 today.
Tubs

A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.

1 user thanked author for this post.

76-j

[Buccaneer]

Tubs wrote:

I don’t know what year you were buying those $25.00 pistons for your
1965 Ford but- $25 in 1975 is equivalent in purchasing power to about
$140.26 today.
Tubs

I think I was making about $3.25 an hour that summer pumping gas!

Prepare to be boarded!

1 user thanked author for this post.

76-j

[jeff-register]

Tubs,

It had to be about 1969 or so. I had the only Corvair repair shop in Phoenix Az. The dealers would send the Corvairs to me to repair. No one would touch them. Once a guy figured them out I could train a monkey to work on them. My friend did a ring & valve job on a 1965 Ford Mercury 390 &  three pistons had oversized ring lands. I don’t know I got a repair shop discount if at all, but the Ford dealer must have given us one?? We had a ball in that shop building sand rails & fiberglass V.W. sand buggys. Remember the corvair lakeside station wagon? We shortened one to a 2 door & put giant off road 15″ tires & a turbo 180hp motor & it was a death trap. We had regular costumers for oil leaks, pushrod tubes, had O-rings on a tube & they “cooked” on a reguler basis. Made some good money for the time but spent it as fast, crazy & young!!! We would do a ring & valve job back then for $180.00 + tax.Yes I’m old now.

[Author]

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