I had a block built that I bought from a member on the forum. He had custom Wisco pistons made from the stock pistons. The block was checked at a machine shop and assembled by an MB mechanic. The Mechanic mentioned the play and said he was not sure what would happen, since he just workes with MB parts.

The question is: The stock piston to rod clearnace is tight but the rods float on the crank on the MB. The Wisco`s were made with more rod-piston float for some reason than the stock tolerences. Anyone see a problem with more piston to rod clearnace than stock? Anything I should check before selling or installing the motor? Pistons also came with Wiseco wrist pins and those were used.

Anyone running aftermarket forged pistons and know how they were set up?

 

https://mbworld.org/forums/2449773-post43.html
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https://mbworld.org/forums/w211-amg/...ns-rods-2.html

 

all wiseco pistons come with a build sheet.the suggested piston to wall clearance is minuim recommend. it is up to engine builders discresion to ad to that if so warranted.(turbo/super charge ect..)piston pin to rod is generally .0008/to .0012 for aftermarket rods .MB factory rods are usually tighter than that.about .0002. i personaly open them to .0005 (factory rod) leave them tight. piston to pin clearance .0006/.0008 should be fine. rod to side of piston fine if greater.rod guided from crank.

 

I wonder if SPEEDYBENZ meant to have float at the wrist pin and crank in the bold sentance below? Is ok to have both? Will they align themselves and not knock?

 

Yes, very nice build sheet included with pistons. Piston to wall is good and even piston to rod is good for some motors but the 55 motor also has floating RODS on the crank design. So, what happens if you have now have piston to rod play and flaoting rods on the crank? Not sure if wisco knew that the 55 had floating rods on the crank. Especialy if someone just sent them a piston to copy on a stock rod.

What have others used with their forged pistons on stock rod set up..

 

Check out the gap between the two rods in the picture. This is how much float is on a stock 55 crank assembly.

 

Interesting stuff. Hopefully someone can get you the correct answer

 

so are you saying your rod is guided from piston? because some are.how much rod side clearance do you have at crank?.floating rod just means pin floats through rod.piston guided rods is somthing fairly new/differant nascar style.does rod bump side of piston before big end bumps crank.or other way around.i will check on that motor today.

 

did not see picture before reply.you have a piston guided rods.piston you have are wrong.you may be able to make a guide that floats between rod and piston.call wiseco

 

The whole motor is together and going in today already. Just checked and we have piston guided rods not crank guided rods. I guess the member that had these pistons made, may not have known how our rods were guided. I did not either, when I tried to check everything before sending him a HUGE bank transfer!

Stock rod width is .785 and stock piston ID at rod is .795. The custom piston is .950! That means I have .155 more side play than stock? To much? Will it still align or will a 45K motor go Kaboom on the first run? From what I understand, .165 rod to piston play is ok on a motor that is crank rod aligned driven verses piston rod aligned.

 

The motor started up and idled fine. Might as well turn the key on, since it was all together already.. Based on the specs I recieved from piston MFG, motor will have to come back out and use thrust washers to take up the slack, on each sie of the piston. Very exepensive mistake..

I guess not many people know that we have top driven motors, as they say. The piston MFG told me, that two sets of pistons were made like this and sent out within two weeks apart. I wonder who is running around with the other set in thier 55 motor?????? How did they make it work or are they just on borrowed time? It has to be a member on this forum..

 

If you don't mind me asking who is doing all this work on your engine. I am always looking for a good shop.

 

This is a one time deal and not a regular work shop. It involved 4 seperate shop entities and custom work. For a good shop in Houston, I also use http://www.lawellmotorsports.com .

 

KABOOM

 

thanks

 

What would be the best material to make wrist pin thrust washers out of?

 

The first thought was copper but on second thought I would
call the rod builder and ask if they could install 2 piece shoulder
bushings. I know more machine work, time and $$$$

 

two piece shoulder bushing way to go.same materail as rod bushing.(brass)make sure piston is machined square to bushing, and then about .010 clearance should do it.

 

About 3 years ago I started to look into replacement pistons for the M-113 AMG Motor. Reason being , I though that at $700.00 a piece , for a Hi sil cast piston was nuts!! even if they came with rings & wrist pins & Clips. I sent them a sample piston. Asked for Dish to be opened up so I could use Larger intake & Exhaust Valves with the possibility of a new higher lift cam. I also wanted to use the ring package from Mercedes. I wanted right & Left pistons with a Wrist pin hole off set .010 . The skirts were to be coated with nickel sodium chloride, not Wisco's chrome plating process. I had to order 10 sets of pistons.
What I got was anything ,but what I wanted.
#1 the second compression ring land Clearance was .004 to wide
#2 they never machined the piston with the .010 pin offset
#3 The piston pin bore was .003 to wide
#4 They forgot it was a top guide rod motor
#5 The piston had there moly slide coat for break in . Not Chrome or what I wanted
To make a Point, I cut a piston in 2 , only to find the dome too thin. I got pissed off and sent all the pistons back. It took them 3 more trys to get them close. I finally just gave up, and gave all them back .
I find out during that time spand , they laid off production people , retired most of their engineering department. Laid off their field sales staff. It appear to me there was a great disconnect in communication within there corp structure.
They tried to feed me what they thought I needed , not what I wanted! Even at {PRI} they were less than helpful.

At {PRI} I had a great talk with Keith Black. He truly understood, what I was after and the top guided rod on these German design motors. I also Visited Mahle Motorsport, Talked to John Goodwin. Both manufacture's understood where I was heading and that piston prices need to be more inline with what consumers felt was fair.I wish I have cash flow I had 3 yearsago. you be sportin Mahle forged pistons instead of Wisco's
Sorry for the bad news on Wisco , in my opinion , they should stick to Motorcycle pistons. most of the guys I know have gone back to Vertex or Mahle Regards _PTEngineering

 

PTE, you hit the nail on the head. Aluminum pistons have to be coated to work in the aluminum bore. It has to be the right coating and the piston has to have the correct expansion coefficient to work in the aluminum bore. The only two piston manufacturers that I know of that make a piston to work properly in an aluminum bore are Mahle and Kolbenschmidt. The rest are ticking time bombs.

 

i never said anything good about wiseco. nor am i intrested in any name droping.i have been doing this for 35 yrs.and i have see alot of people that spend there money before investigating.i also see alot of mr. no it alls. so were are we going with your e mail. was it directed at me?

 

Mr Bigblocktrader , this thread answer was not directed to you , This is just my experence over the last several years in dealing with Wisco. I was trying to get a quality part, that I could pass on to the MB world members at a fair price. Wisco made so many mistakes. So, I thought it would be a wise thing, to pass on my poor experences. I got the E-mails , did you get them also? I respect your experence & input . keep it coming !! Regards _PTEngineering

 

thanks ,not use to these forums.didnt know once your in you get threads to your email box.didnt want to get to involved in others problems. but i will agree wiseco pistons are for high school kids.

 

So you found lower compression forged pistons and forged rods for our cars for an affordable price?

 

Tommarrow have family over.Peace