got the cilinder diameter measure from machine shop... what would you do ?

[Nacho-RT74]

After 9 years from last engine job ( sleeved ) and 35K miles on it with stock standart pistons, dissasembled the engine. Just got the cilinder measurements: 0.0024" to 0.0025" over the standart bore... so, vote and if you have some opinion, please post.

( KB215s to be used )

I would like to keep standart, but, expert opinions are welcomed

[b5blue]

Your new pistons will dictate finished bore tolerance, my machinist needed new pistons in hand after checking bores to determine the overbore range needed. (.060!)

[Nacho-RT74]

I have to buy pistons IN USA, so I can't buy for example standart and then machinist say me IT WON'T WORK, so That's not an option

If I have to make that, would need to buy 0.010 without think it.... with of course the extra investment on the Rings what I don't have ( I had ready to install standarts )... but If I have to ...

[Nacho-RT74]

HELL NO... THERE IS NOT 0.010 OVERBORE!!!! Dunno why I thought on that ( maybe thinking on stock pistons ratios ) WOULD NEED TO CUT TO 0.020" forgett it, I won't cut a block like that just for 0.0025"-0.0030" over the standart bore!


unless you have other opinion about ?

[John_Kunkel]

I'd say it depends on what you want to do with the motor, if you're looking for maximum performance then bore it and new pistons. If you can live with a little rattle and oil consumption go with honing and new rings.

I'd hone it and go.

[Nacho-RT74]

I think Maximun performance is to be on more race use than street use ratio... I don't think ever race it, more than some traffic light for fun between friends... and couple of pass on track JUST to know 1/4 mile time, but never to enter on a competition.

[b5blue]

For you think "how long" till next rebuild, .0030 isn't much but where on the cylinder wall it is "out of round" will only get worse. I assumed you were replacing the pistons. (I waited and saved extra money to do a total rebuild.) (It took much longer than I ever thought it would!    )

[Nacho-RT74]

well machine shop didn't told me anything about walls are out of run ( I guess you mean elongated cilinder ). I'm seeing on this way, the engine never asked for a rebuilt, is just that I was to work on it to add some power no matter which option I was to go, using 383 forged crank with standart bore KB240s what I already had as the initial project, or once I got accidentally the 440 crank and now needing the KB215s to the 451. If wasn't for that, engine would keep running on same way, same stock pistons day after day, same bore and natural cilinder wall worn day after day untill REALLY NEED a rebuilt job, and thats maybe around 50-60K miles added to the actual 35K the engine has... maybe 7 to 10 years more from now ( if we think I got 35K miles in 9 years on an allmost driver use )

how many miles you wait to rebuilt an engine in USA ?. Down here an engine is rebuilt after around maybe 150K Kilometers... of course that's if you don't get any trouble with engine, as an earlier bad failure for any reason.

and I'm thinking on somekind of work on cilinders ( hone ) because the diff ring height, what will get over the 0.0025" step "made" no matter which way of the project I use.

[firefighter3931]

If it were mine : The overbore would be .030 with a fresh set of pistons/rings. 


Ron

[Nacho-RT74]

LOL, same than a friend told me, who prep his cars for race ( 70 Chally and 68 Charger  ).

he gave me a valid reason and is not for performance purpouse... in case of a block damage or earlier failure somehow, I can get any street block around to bore it .030 and keep the pistons.

HOWEVER, 400 blocks doesn't grow on trees around here either, but still a valid opinion

[femtnmax]

Since the block is worth more than a set of hyper pistons, how about buying a set of forged pistons?  The forged will need more piston/cylinder wall clearance...possibly just hone what you have and end up with perfect clearance, and not have bored .03 over.

[Nacho-RT74]

no forged pieces on that diameter nor to 383/400 rod from the shelf, would need custom