will rings seat after block getting honed

[ryan's rs]

I have a 420a motor bored .20 over already bought it like that, the person i bought it from did not run it with a mega squirt. then i bought a mega squirt installed it and it ran fine for 6 months then i heard a lower end noise in the motor when going over 1500 rpms. then pulled the motor and found out it was the fly wheel cracked all the way around where it bolts to the crank. But while the motor was out i went a head and pulled it a part to make sure. then found out the pistons where melted on one side of them from running to lean because of not having the mega squirt from the owner before me. Now i have the motor at the machine shop and found out he had the block bored .20 over already and was wanting to know if it was ok to go .40 over or just let it get honed and have .005 to .010 thousnads of an inch off. Will the rings seat after the honing or not? This motor has a turbo and i was running 20lbs before and will be running 35lbs after the rebuild. Yes the head is built already just need to know if i should hone it or bore it. Thanks

 

[talonDSMerr]

You'll need to have it honed regardless of whether you decide to bore it or not. The hone is what creates crosshatch on the cylinder walls for rings to seat. The hone is also how the piston-to-wall clearance is set for each individual piston and cylinder.

Make sure you know the specs your motor is being built to and what the clearances will be. It doesn't seem like you have a strong grasp of what is going on while your motor is at the machinist's..

 

[TheEagle]

I agree. It doesn't seem like you have the strongest grasp of all that is going on here. Anyway, understand that most oversizes are the .02, .03, and .04. Much bigger and it can...cause issues. Understand that when you go to .040 its hard to find pistons and harder to rebuild if it ever get out of round. So I would not recommend jumping to .040. I kind of doubt your running a .2 oversize...

Either way honing will be done. .005 will not change anything, though I would get new rings. Read more into ring gap settings also.

Also before even thinking of running truly high ibs, understand fully what that means. Can have some serious consequences if you mess up. Just my 2 cents.

 

[WES_393]

The OP is asking if he can get away with honing out the damage or should he bore the cylinder completely, not if the cylinder needs a hone.

I wouldn't hone the cylinder any farther than the piston to wall clearance specs of your aftermarket pistons. If the walls are damaged, I would bore the cylinder and then have it honed to the correct size. Too large of a piston to wall clearnce can cause piston slap and stress cracks on the skirts. But ultimately the machinist should be able to tell you how bad the damage is and how far they need to bore/hone the cylinder.

 

[bullettdsm]

As stated, the machinist should tell you if you can just hone the walls or if you need to bore to a bigger size.

You should have no problem finding/using .040 over pistons. We have plenty of wall in our blocks.

MB

 

[Fotowntalon]

Risk Vs Reward, I might be getting a little to into it for the OP, but going .040 will net more power and pistons will still be pretty available, then again if something ever goes wrong and you need to bore more out you will need to have a custom piston made, for I don't believe they make .060 shelving pistons. If its just your DD that you just want to run right, do as little as possible to get it all cleaned up (your machinist will tell you if you can get away with a hone or need it bored out. If you are seeking max power, no reason not to bore to the max with a custom piston imo.

 

[ryan's rs]

well they only make .20 over pistons and .40 over pistons for the 420a witch i knew already so it wont be hard getting the pistons.This is why i asked if the rings will seat after a .005 is taken off or not. I dont even want to go any more then .20 over to be truthful but i dont have any choice in the matter since it has already been done from the person that had the motor built before me. I dont need rings by the way i need new pistons because they are melted on one side and the melted pistons are .20 already that is why im asking if i can go to .40 over or if a new set of .20 pistons will seat after it getting honed half of a thousands of an inch.

 

[TheEagle]

you can get a .030 racing piston around, if my memory isn't failing me. Maybe DSM graveyard will have more info on this.

 

[ryan's rs]

they do have the .030 over piston but they will not work with my forged eagle rods since they are a floating rod.