Merc 2.5 piston/rod what do I have?????

[dwilfong]

340546340545340544340543340542So what do I have here........any help would be greatly appreciated.

[superboattwin250]

Looks like a 5250 Merc rod, With Pistons that were pinned by us1 with his rings. The rod bolts don't look familiar to me though. Never seen Allen ones

[eli]

rings are for side pin allen rod bolts ?

[patchesII]

I'd chunk those bolts as far as I could and put ARP bolts in it

[dwilfong]

what pistons are thy????..... Mahle???....Merc HP???
Yes the rod bolts are junk I feel looked it up and thy are china junk grade 12.5
The rods big end side to side measured the same as the 141 I have.
Now I have to make a dissection big rod or small rod????????............:rolleyes:

[TEXAS20225]

.712 is width of tg rod looks like bottom guide pistons with the thick washer for rod that have been thinned .050 on each end or maybe just top but that cant work if its .812 on bottom it will be tg and bg together, inspect the snap rings closely they get to wobbling around in there and boom over the hill gang out

[tlwjkw]

if whoever can't get tha rings right, what else is screwed up with 'em?.... i wouldn't use any of it in something thats gonna be right everywhere else...........jmo

don't think mahle's are "full shouldered" at tha pin boss'es......

[dwilfong]

The bottom of the 5250 rods are .712 and the top is .783
The distance between the piston bosses are 1.072
So how much side clearance is needed for a top guide setup at the piston bosses:?
I think I will use the 141 I have prepped but need to know how much clearance is used at the piston boss on a top guide rod.
Looks like I can use the 141 rods and the wide washers on this setup along with the standard washers and come up with .016 side clearance.

[dwilfong]

Well broke them down and with the spacer and the stock washer I get .023 clearance.
The rings are modified for top pin.
The forged piston is only 3g heavier than the stock cast one.
Measuring the crank pin width and the rod bottom width there is .120 clearance.
So what you all think??????

[tlwjkw]

use whatever ya want but don't like any piston tha doesn't use "rectangular rings" that are modified for tha top pin.... tha end gaps stacked are a negative far as i'm concerned with those type rings jus make it worse.... other than not shakin' lose don't see tha advantage of top pinned but 'bout only choice nowdays..............

[dwilfong]

well the story gets deeper.........

[dwilfong]

340600340601well the story gets deeper.........
1 Mahle and 5?

[eli]

weigh one of those they look heavy

[dwilfong]

same weight as the cast pistons..............