Installing replacement pistons
 

Received new piston assy’s from original builder because original pistons had issues @ 2000 miles. Cylinders look good @ still show original honing pattern but I know I should re-hone them. I see two types of honing tools, deglazing which I think will be fine or full honing tool. With the original honing pattern still evident What r some thoughts/advise?

Re: Installing replacement pistons
 

Always hone to assure proper ring seating and use proper honing oil , the left over cross hatch had rings already wearing against it , it is a good idea to start with a freshly honed cylinder, you indicate there was a problem with the first ring /piston assembly so start with the correct cross hatch and proper grit of stone to suit the type of ring material to insure good ring seating, always clean with hot soapy water and wipe with a clean rag to check for left over hone abrasive. for just a re-ring job I use the expandable spring type purchased from an auto supply or the berry bush type , after a re-bore in order to bring cylinders to size clearance ,proper finish, I use a Sunnen A N micro adjustable . be sure to check ring end gap, Piston ring land clearance,depth etc. and piston to cylinder wall clearance, you didn't say why the other pistons failed , if you don't mind what was the failure of the pistons at such low mileage ? this sounds like the pistons may have been installed incorrectly or a number of other contributory factors.

Re: Installing replacement pistons
 

Since you have a correct size and just want the surface for the rings a flex hone is the easiest way to get the job done correctly,
Brush research flex hone...any ridgid hone or glace breaker needs pressure adjusted right to end up with the right finish.
Just my 2c.

Re: Installing replacement pistons
 

A rigid hone will also remove some material and may effect piston fit.

Re: Installing replacement pistons
 

I’ve seen the brush type too. Considered but all seem to use carbide in them. Carbide can cut quickly?

Re: Installing replacement pistons
 

The flexhones removes a minimum amount of material to achieve the correct wall finish compared to an oldfashioned ridgid stone.

Re: Installing replacement pistons
 

Opinions on this type? https://www.amazon.com/dp/B002XUL1EE..._9cfmEbEVN9RWR

Re: Installing replacement pistons
 

If you have cast iron rings...not moly or something exotic like low tension...that brush wil get the job done !

Re: Installing replacement pistons
 

Just curious, whatwas wrong with the original pistons & rings.

Re: Installing replacement pistons
 

That is what I am wondering also , what will stop the new pistons from failing ?

Re: Installing replacement pistons
 

From your previous thread, I think I would check clearances before reassembly.

Re: Installing replacement pistons
 

I believe he had a detonation problem and destroyed some ring lands . . .

Re: Installing replacement pistons
 

Ever since I read the replacement ring set instructions that said honing is not necessary if there is no bore damage I don't hone, --- even experimenting with putting used rings from another engine in (used rings with 180k in 200k bores)
I have taken apart recently honed and new rings engines apart for bearing failure due to honing debris

Re: Installing replacement pistons
 

Yes all that can be correct in many cases,the cautionary statement exists because the average shade tree fixer either doesn't know what is required to get a acceptable job done or is following 50 years of bad info and practices.


R

Re: Installing replacement pistons
 

Ol’ Ron & Fordestes- As Bored & Stroked said, Builder believes detonation is what caused. From another thread I posted when I removed heads, Offy. alum. & discovered from many who posted there’s an issue with the head design regarding s. plug reach. Short story no plugs made in correct heat correct length. My builder put 437 reach Autolites which were .250” short & not entering the fire chamber causing detonation which cracked land between rings on 4 cast pistons. New pistons r Ross Forged. Offy Heads counter sunk @ 120degree to flush thread condition on plugs as recommended.
Kurt & Ronnieadvice if cyl’s not damaged don’t hone have me wondering now if I should or shouldn’t hone? W only 2000 miles on engine when this happened it still has original honing pattern showing?

Re: Installing replacement pistons
 

You need to check the piston clearance. Forged pistons normally require more clearance than cast. If you hone the cylinders you need to figure out how to not contaminate the rest of the engine. If it was me, I would pull the crank.

Re: Installing replacement pistons
 

Yes you should hone it isn't easy to not contaminate the rest of the engine.


My first post explained why the no hone was stated. Not my belief that honing must not be done. I myself haven't seen a current no hone statement regarding any common replacement rings.



R

Re: Installing replacement pistons
 

I don't know if I'd accept the builder's explanation of what went wrong, especially since he was the one who installed the incorrect plugs. He either didn't check them or chose to ignore the obvious mismatch. If the latter, why does he know it's a problem now when he didn't then?

There are some red flags here for me, anyway.

Re: Installing replacement pistons
 

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Re: Installing replacement pistons
 

Tubman, I don’t know what was in the builders mind but am skeptical also. Remembering before any dis-assy, always adjusting for what I thought were timing issues. Since dis-assy & the long discussion on Offy head issues & seeing the dark condition of tops of pistons & remembering also no matter what plugs I used to use they’d all be dark on removal. Even had Charlie NY set up carbs on his test engine & still had plug issues. So on removing heads & seeing plug reach so short, & long post/thread on Offy heads seemed to make sense. Be that as it may I gotta re-assemble.
I don’t want to pull the crank. Plans were going to b:
Wrap exposed crank bearing surfaces with clean flannel to protect while honing
Hone w brush style lightly to just break potential glaze
Clean bores w terrycloth soaked w kerosene then flush wipe again w brake cleaner.
Final clean w clean terrycloth till clean.
Remove flannel from crank flush wipe w brake cleaner crank surfaces w terry cloth till clean
Check piston to cyl clearance, JSeery said forged s/b greater than cast pistons, how much???
Verify compression ring gaps
Reassemble
Comments?