What's considered EXCESS wear, 340 bore

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Captainkirk

Captainkirk

Old School Mopar Warrior
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FOR A PERFORMANCE BUILD....what is considered an excess amount of cylinder wear/taper before considering oversize boring?
One book puts it at .006 taper/out of round. But I am referring to a street/strip PERFORMANCE build with no desired piston slap or oil burning...in other words, done right.
I'm in the process of mic-ing out my bores right now so would appreciate hearing from any pro builders ASAP....
 
Man I dont like to see anything more than .0005". The most I would deal with from a std factory bore is .002. Anything more than that and I would bore it for a fresh true, straight round bore with torque plates. Some pistons like to see .001-.0015 piston to wall, anything more than that and piston slap is inevitable.
 
My answer is it depends on what type piston you run and what you are doing with said engine.
 
MRL Performance said:
Man I dont like to see anything more than .0005". The most I would deal with from a std factory bore is .002. Anything more than that and I would bore it for a fresh true, straight round bore with torque plates. Some pistons like to see .001-.0015 piston to wall, anything more than that and piston slap is inevitable.
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Thanks. Right now, from the cylinders I've checked with the bore gauge, looks like maybe .001 taper on the thrust sides. Forged Speed Pro pistons
 
I would run it and never look back. But I am sure there are those who will scoff at me.
 
I have a buddy who had .008 thou in his Clevo, Liberty 4 speed and 150 shot of N2o..Against all odds it hung together...
 
"Right" to me means bringing it up to what is technically possible now. From that point of view MRL's right - less than a thou is what I'd want to see and on a fresh bore/hone it better only have some at the bolt bosses from using the torque plate. Otherwise understand it's not "right" by my standard but it should run acceptibly given you're not racing it. You mention taper, but there's out of round, and piston to wall clearance to take into account too never mind it being not perfectly perpendicular to the crank centerline.
 
ir3333 said:
isn't the L2316 a flat top that sits about .020 out of the bore
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Yes. The old ones were domed L2322's with a static CR of 13:1 but the skirts and ring grooves have enough pitting to make me leery of using them. The L2316's are a static CR of 10:1 with standard cc chambers
 
moper said:
"Right" to me means bringing it up to what is technically possible now. From that point of view MRL's right - less than a thou is what I'd want to see and on a fresh bore/hone it better only have some at the bolt bosses from using the torque plate. Otherwise understand it's not "right" by my standard but it should run acceptibly given you're not racing it. You mention taper, but there's out of round, and piston to wall clearance to take into account too never mind it being not perfectly perpendicular to the crank centerline.
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The issue at hand is, well...to bore the standard block I have, buy pistons, rings and pins and fit them and possibly deck the block will add around $1200.00 to the bottom end of the motor.....which could well be used elsewhere. That being said, I don't wanna half-a$$ it and have problems down the line with piston slap, blow-by or oil consumption. This is why I decided not to mill the domes on the 2322's.
But again; I don't plan on racing, and if I do, it will just be to establish a baseline ET for my own information. Not into competitive racing at this point.

FWIW, I miked the thrust side of all 8 bores and came out with pretty much .001 across the board...one might have been a bit closer to .0015 but none of them were as bad as .002. But some of you make a very valid point WRT torque plates.

Sounds to me as if you are recommending boring (with torque plates) as well. This is what my engine guy is recommending.
 
You're really the only one that can determine if "good enough" ...is. It will run. It might run well, for years and years, abuse or not. It also might only do it for a while, or not run well at all. Or it might have some noise, and/or some oil leaks or smoke from blow by after a while.
If peace of mind is worth $1200 there's one return on investment right there. It's not all about drag racing. It's about efficiency and longevity, both which come with "doing it right" and then not worrying about it.
None of the posts here are wrong, nor is your machinist. Ultimately it's your money, it's your decision.
 
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