Mushroom plugs ??

[1962polara]

I just took delivery of my max wedge engine.It's got strange aluminum plugs on each side of the piston pins !

The pins are floating on the rods so the mushroom plugs keep the pins in the piston .I would have thought wire locks would have been used.
Anyone ever seen this??
The pins are to spec ...so the rods must have been relieve ??

EDIT
I dismantled it and the pistons are knurled.Also found a score in one bore here's what I found.

 

[miller]

I'm not lucky enough to know what is 'stock' in a max wedge motor, but in a word, they were experimental at any rate.
The piston pins free-float in the rods, too...right? Those aluminum end caps in the pins do exactly how you think, keeping the pins located right, the caps rubbing the cylinder walls. Most air-cooled radial aircraft engines use basicly the same free floating piston pins, with aluminum caps. Some caps are loose, some are pressed fit. For your motor, it really depended on the thought of the day, what would work.
The knurling bit on the pistons could be for closer clearance, for 'catching' oil on the side-walls, or both. Seen 'em both ways. How bad is that cylinder wall score? And, look hard to figure what caused it.
Jealous! Have fun with that tinker toy.

 

[PoppaSmurf]

Those are wrist pin buttons, and are still used today in top fuel cars to keep the wrist pin located within the piston bosses, back in the 70's and 80's they were pretty widely used in anything Super Stock and up classes doubtful they caused the scoring of the cylinder wall..

We saw these a lot when I worked at Lunati Cams.... Chances are your Max Wedge was a race engine at one time or another

http://www.cbperformance.com/v/vspfiles/photos/5293-2.jpg

 

[Meep-Meep]

Yeah, pin buttons are not factory. MW had pressed pins like the other big blocks but forged pistons just like in your pic.

 

[1962polara]

Thanks Miller,Poppasmurf & Meep,

I googled it and now understand Would it be ok to keep it this way Or bush the rods?

engine came out of a dirt racer.

One other thing I noticed is the crank main journals have been grooved and the bearings are un grooved ...why would this be ?From what I seen it's opposite other setups.

 

[Meep-Meep]

Grooving the mains is to increase oil flow to the rods. Same as fully grooved bearings. Ford grooved the crank, MoPar did it with fully grooved bearings and others would cross drill the crank.

Those pins look horrible like they have been overheated. Time for a new set I say.

 

[miller]

I used to deal with wristpins that looked like yours all the time. Though it was on aircraft motors, it's all relative, parts is parts. Of course, what parts you use is up to your preference.

'If' there is no galling, scoring, excess wear or the like on the pins, they could be polished up and re-used. But, you'd need to check the rods, and pistons for any wear, too, and see if the clearances are still good.

Right now, you have an open book, and can put the motor back together any way you want, using any parts you want, including those rods and pistons. A good chance new pistons would take dif type wristpins. Might be hard to find same part number pistons as you have. If there's much wear in the motor, probably have to do a all the above.

 

[wedge69]

THAy are calle dBumper pins. That the old way thay did full floating pins. There Not a bad deal and work well. From the looks of things I would say that engine was bult to race ! Bet the block has opened oil gallaries also.

 

[miller]

Just something I might add, after looking again at your photos. That crank looks real good! The grooved main journals some would call full race. No telling how many times the motor was overhauled. Do you have any idea how much time on the re-build? How long has the engine sat?
At the mains and rod journals, looks like lubriplate. It's possible, if the motor has sat for awhile, that lubriplate can harden, possibly blocking a oil port. Only takes one to make a bad day.
Hope you plan on a complete overhaul. You've got some good parts to start with.

 

[1962polara]

Not sure when it was last rebuilt but it has sat for over 15 years,not much wear either.
Miller yes that stuff (good info) has hardened but still soft under the bearings.
I plan on a total rebuild .
Yes the crank is perfect just needs a polish same as pins.I would like to keep the original parts (I have a set of original NOS pistons & rods ) but I hear comments on how heavy the rotating parts are ...I'm not looking to race just keep original.
What would you guys do?

 

[miller]

Gotchya! Here's the jealousy coming again. For it's day, a 413 was a great motor...moreover a max motor.
Sounds like you've got the right idea on what to do with it. Assuming you got the intake with it? Your photos look like not much running time on that build, just sitting time, as you said. Might just need a fresh, complete clean-up if there's no normal worn parts. Yeah, that lube is good stuff, but not made for long term.
I'd also look good at your bearings/inserts, unless you plan to put new ones in. Probably be a good idea. Sometimes bearings/inserts can get hard spots on 'em, from sitting for a long time. Piston rings don't like sitting long, either.
I'd recommend checking ever oil port through-out the motor, making sure they are clean and clear. Good luck on that thing...you should have a blast!

 

[dvw]

Lots of old school tricks there. As a current race motor, a gamble. As a fun street/hot rod motor? I'd polish the crank and piston pins, Ball hone it, check the bearings and valve springs and throw it back together.
Doug