Fresh hone?

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408 Nova
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Fresh hone?

Post by 408 Nova »

Buddy of mine brought a 421 into the shop that has less than 1000 miles on it. It had Diamond flat tops in it that were vertically gas ported by an engine builder friend of his. For some odd reason, two of the pistons broke between two of the holes that he drilled, adjacent to the intake valve reliefs. His builder is deployed right now, or he would fix it for him. He's got a fresh set of pistons ready to go back in.

My question is, do I need a fresh hone on the block, as per the finish reccomended by the ring manufacturer, with no more miles than it has on it?
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Re: Fresh hone?

Post by mag2555 »

No you do not need to rehone it as long as you can still see crosshatch on the walls where the rings ride!
Non chrome faced rings these days are lapped at the time of manufacture and many OEMs and builders after normal honing use a ultra hone / plateau hone which makes things seat instantly on fire up, and this is where you are now with 1000 miles on the motor.
If you just feel you must then use some wet or dry 1000 grit paper and WD-40 and give the walls a quick go over and call it a day!
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Re: Fresh hone?

Post by BillK »

408 Nova wrote: Fri Jun 15, 2018 3:19 am For some odd reason, two of the pistons broke between two of the holes that he drilled, adjacent to the intake valve reliefs.
Sounds like detonation damage. I would be more concerned with that than the hone. Probably should look at all of the pistons to make sure none of the others are getting ready to do the same thing. Also, check ring end gaps to make sure the rings ends are not butting when hot. If he is running it hard then a little too much ring gap is better than not enough.

As far as honing as long as there are no terrible scratches I am going to agree with mag, leave it alone.
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mag2555
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Re: Fresh hone?

Post by mag2555 »

I may be wrong , but since you state this has 1000 miles on it like what sounds like a street motor , then why the heck where the Pistons gas ported in the first place, and what thickness are these rings?
You can cut a man's tongue from his mouth, but that does not mean he’s a liar, it just shows that you fear the truth he might speak about you!
408 Nova
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Re: Fresh hone?

Post by 408 Nova »

All good questions and advice. After really talking with my buddy, he said the motor has less than 100 miles on it, and that really makes me lean heavily towards not honing it, like you all have said.

We have a fresh set of rings to back in the motor also.

My buddy also told me that he never ran any kind of pump gas in the motor. He ran either Renegade race gas or VP race gas in it. I wouldn't think it would've detonated on those two fuels, even with his near 12:1 compression?

And as far as the gas porting is concerned, I'm with y'all. Eventually carbon will stop up his gas porting, and stop working, and maybe have some other ill effects from the carbon.

The Diamonds I believe were 1.5/1.5/3.0 mm rings, and his new Howards pistons are 1/16"/1/16"/3/16" rings.
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Re: Fresh hone?

Post by David Redszus »

If it were my engine, I would use a surface profilometer to measure the wall surface. Just because it has limited miles does not mean the bores were properly honed in the previous build.

But, I would also be concerned with the reason for failure. Simply replacing parts invites a repeated failure.
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Re: Fresh hone?

Post by Walter R. Malik »

Even IF the finish is correct; when it is not straight and round with a plate installed ... hone it till it is.
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