hone without bore??

[brad92t]

I think this might be a pretty dumb question, but I can't seem to get a consistent answer from the people I have talked to.

I am doing a rebuild right now, and like anyone, the last thing I want to do is spend more money than needed. Is it possible to just hone the cylinders without boring them out and reuse the stock pistons? Or would this remove too much material?

I was reading that the hone should remove .003" to .005" so I am assuming that the cyl clearances would be checked, and if they have that much room left on tolerance, and the surface isn't badly marked up, they can simply be honed and the stock pistons reused..

Good idea/bad idea? Comments?

 

[figgie]

of course

but the question is SHOULD you?

The 7m block are cast Iron and some damn sturdy cast Iron.
Hell with 200,000 mile on my block the damn cyliders STIULL have the OEM cross hatch pattern!!

If you really want to hone you can but keep in mind that requires regapping the rings to the new bore dimensions. Yes Honing DOES take out some material so that requires the new ring gaps.

The bad part is that the new hone might take the old pistons out of tolerance and thereby needing to buy new pistons and the reboring the block and honing to the new piston size.

 

[jdub]

Take a look at this for my suggestions on a re-build:

http://www.supramania.com/forums/showthread.php?p=216122#post216122

And what figgie said is very valid!

 

[brad92t]

The 7m block are cast Iron and some damn sturdy cast Iron.
Hell with 200,000 mile on my block the damn cyliders STIULL have the OEM cross hatch pattern!!

well, reason for rebuild was rod knock, and reason for rod knock (obviously) oil starvation

long story short, the cross hatch definitely is not evident, and there are vertical lines on the walls...but i also cant feel any marks with my fingernail

this is my first time with an engine apart, so i am not that knowledgable and have only been going on the advice of friends so far.

needless to say i am going to be taking all this stuff to an engine building shop for the work.. i just want to be armed with knowledge beforehand

thanks guys

 

[jdub]

long story short, the cross hatch definitely is not evident, and there are vertical lines on the walls...but i also cant feel any marks with my fingernail

Hmmm...I'd bore it .020 over. That means new pistons...take a look at Wisco. I just had a set in my hand a couple days ago and they are nice...don't cost an arm & leg either. Make sure your rod bearing surfaces are not damaged and get dressed properly. Rod bearing clearances are critical and must be in spec..."that's about right" will not work.

 

[MDCmotorsports]

Boring actually removes move than honing.

In your case, I wouldn't worry about to bore or to hone, but you need to make sure your cyl walls aren't egg shaped or tapered.

Then make a choice.

IF the cyl walls are aok and straight and round, then you could go through with a light hone with a generic ball hone and a drill with wd40 or light oil.

You will have to get a new set of rings and gap them, but with a light hone I believe you could reuse the stock pistons or at least new stock size ones.

 

[brad92t]

Rod bearing clearances are critical and must be in spec..."that's about right" will not work.

thats what im afraid of.. i havent been able to find any "import friendly" machine shops around here, although there are plenty of race engine shops..

i just dont want to get a guy that says "why not just drop an SBC in it??"..

we need a thread that people can print out and just hand to the machine shop that details all the requirements and peculiarities for a 7m build lol

 

[figgie]

dude

race engine shops are not that stupid.

They get paid alot of money by race to build to the customers SPEC not thier own. I usually will take a race engine shop over anything else because they know what messing up a clearance does,

btw

You are in chicago

Sound Performance

case closed.

 

[brad92t]

Sound Performance

case closed.

sorry i don't have that much money.

trust me i have looked into it and i would love nothing more than to have them do it.

 

[MDCmotorsports]

sorry i don't have that much money.

trust me i have looked into it and i would love nothing more than to have them do it.

Nor do you have a 2jz or a mk4.

Also, think twice about a "race engine shop" unless you know the shop's ability to do an engine to correct specs.

Alot of race engines are built sloppy due to the fact they want the most performance out of them for a short time.

 

[Nick M]

long story short, the cross hatch definitely is not evident, and there are vertical lines on the walls...but i also cant feel any marks with my fingernail

Overbore .5mm, if the money allows it. Don't rering and hone in this case.

race engine shops are not that stupid

:werd:

Don't use a Sears home special hone. The 7M gets a 400 grit stone. IIRC.

The instruction for the bearings are actually pretty easy. It is first grade addition, follow the TSRM if you rebuild now.

 

[malloynx]

wheni rebuilt my motor with a 167,000 miles on it; my machinist couldn't believe how good the cylinders walls were. i went with just a hone and new ROSS pistons and rings.

car runs very well

 

[Allan_MA70]

My engine only has 29,000km on it ( In japan they spend MANY hours idling in traffic - thus scuffed bores ) but im geting ROSS .017 OS (Yes from HPF! :icon_wink )

If your going a budget build a hone and rings will "work" but if you can afford pistons do it!

 

[figgie]

btw make sure if they bore out the cylinder to use a TORQUE PLATE!!!