final bore dia????

[texasvector]

whats final bore diameter on 2.5 steel motor for cast pistons?

forged pistons??

do vertex have built in clearance??

[W2F a V-King]

Per Mercury High Performance service manual s/n D030200 thru 0D936999 Bore Dia, 3.500 +/- .001 in. Taper/out of round .006
Per Mercury Service Manual (fish motors) s/n 0D082000 and above Bore Dia, 3.501 Taper/outof round .006

Yes, the Vertex has built in clearance. There is a special note for added clearance for cast iron sleeves. In the instructions that came with my Vertex pistons.

Your Forged Pistons should have special notes in their instructions as well.

HTH

James

[FMP]

Find out how much clearance works best with each piston type and sometimes even cylinder#. Most pistons are built to the clearance needed for the indicated bore size on the box. Check each piston size and finish the bore to the individual piston, check ring gap as you approach finish if gap is to be changed or just hope it's good.

[TEXAS20225]

wow ive rebuilt over 300 2.5 mercurys ,good thing i did not have that thought process in my library my machine would have refused my business

[FMP]

Wow you don't check your pistons or end gap you must be good. I haven't rebuilt 300 motors but the ones I have done everything is checked. I assumed everyone checks these things before assembly regardless of which engine it is ? I guess once you can trust your machine shop to do it right the first time that helps.http://www.screamandfly.com/showthre...78#post2884378

[TEXAS20225]

your never going to find a piston thats not within tolerance, ever, ring gaps i check every motor you will,find different gaps with different rings in the same hole , ive had a very hard time finding good machine shops i used ruck for years that dried up now its James Perry( he is better then ruck ) his machine work and porting is the best ive ever seen ever

[TEXAS20225]

final bore on a 2.5 fishing mota 3.501 for standard bore, every piston ive ever bought says on the bore the hole .015 over for this piston my way of thinking is add .015 to original bore spec or .020 ,.030 what ever piston u r using

[rock]

I have doing them that way forever. I do my own machining so all mistakes are on me.

Rock

[wrechin2]

Kind of a trick question..... Sometimes it depends on end purpose of engine. If I am doing a standard build I put them at 3.501 using stock, pro, or vertex. And like Bobby stated, you will get different ring gap readings depending on manufacture. If I'm building for high RPM I will add an additional .001 to .002 to the final bore depending on how high of RPM. Just my .02 worth.

[texasvector]

i ended up with 3.516 final bore using +0.015 vertex.....which have 0.005" clearance built in

im prolly a tad tight for how its gonna be run....but gonna take my time with break in

like rock said....if i squeak it...its on me!