Cylinder bore questions.

[CTS13]

I dont have a bore gauge and don't really have 100 bucks to spend on one. Is there anyway to do this without anything more than a micrometer or feeler gauge. Also how crusial is gettin rid of the cylinder ridgline that forms on top. I'm not boring or honing the walls because they are in spec with no damage to the walls whatsoever so im just gonna deglaze them for the new piston/rings.

Thanx.

[seang]

A Ridge Reamer

[CTS13]

can this be done with just honing stones?

[seang]

I don't know. I would just rent the tool for free at autozone, or a similar store.

[seang]

I don't know what to tell you about the bore gauge. Maybe you can rent that, too. I think autozone rents every rebuild tool.

[sx moneypit]

My old school rule of thumb is as long as you dont hang a fingernail on the ridge a hone should be fine.

[CTS13]

See you can deff feel the ridge when you put your finger over it. and when you slide your nail over it, it doesnt get stuck, its smooth and goes over. it doesnt catch your nail.

After doing some research, people are saying not to use a ridge reamer as a noob because you can mess up the block.

The block itself has over 150k miles on it. Im debating on if i should just do the .020 over or just use standard size pistons and just get rid of the ridgeline. The walls are in excellent shape and taper is at its minimum. Idk.

[Terrorinc17]

With out a bore gauge you will never know what the taper is. Go .20 over call it a day.

[CTS13]

If funds werent tight, i woulda caled it a day few weeks ago.

And you dont needa bore gauge for taper. You can use a piston ring to find out taper. I need a bore gauge to check if my bore is out of round or not.

[Terrorinc17]

Good Luck, I think I have a set of std bore Weiscos with like 500 miles on them if your interested.

[sx moneypit]

If it is a KA, i would just give it a good hone and go standard size. I would not be scared of just ringing it as long as the pistons are good.

[CTS13]

Well im going with cp pistons and eagle rods.

[sx moneypit]

Sounds good!

[CTS13]

See the only thing was i didnt want to hone it mainly because the taper is actually within specs and i didnt want to mess that up in any way. On top of that, i didnt want to take anything off the walls to increase the piston to wall clearance. I was just gonna get rid of the ridgeline and deglaze the walls with a brush hone.

[seang]

When you have the new pistons, you could check piston to cylinder wall clearance just to be sure.

[CTS13]

I can just do that with the old pistons right. Cuz i dont want to order new ones and then gotta find out i need oversize parts cuz the theres too much clearence.

[seang]

I can just do that with the old pistons right. Cuz i dont want to order new ones and then gotta find out i need oversize parts cuz the theres too much clearence.

Correct me if I'm wrong, but forged pistons can require different clearances than stock cast (and probably hypereutectic) pistons.

[CTS13]

I'm not sure about that one but it would make sense.

also another question that popped into my head was, if you order oversize pistons, lets say .020 over. Does that mean the piston is smaller than 3.524 or does that mean the piston is 3.524 and you have to bored to walls over 3.524 for the clearence.

[seang]

If you bored it .020 over, the pistons would also have to be .020 over stock.

[CTS13]

Well ya i understand taht part. But usually piston to wall clearence is around .001 right? So does that mean i have to hone the walls after the bore for another thousands of an inch or after the .020 bore, i can just drop them in.

[Terrorinc17]

If your spending the money for new pistons and rods, do yourself a favor. Take it to a machine shop and have it done correctly. It will save you a ton of $$$ later!

The typical piston to wall clearance is about 3 to 3.5 thousands. If your going turbo you may want to increase it to around 4 to 4.5 depending on what the piston mfg says you need and how much boost you will be running for your application.

If your going to be going .20 over then the bore needs to be 3.5 over that. You will never ever do a good job with a drill and hone trying to go .023 over stock. Besides it will probably be under $200 to have it done correctly.

Just my 2 cents.

[liquid_cool]

If your spending the money for new pistons and rods, do yourself a favor. Take it to a machine shop and have it done correctly. It will save you a ton of $$$ later!

The typical piston to wall clearance is about 3 to 3.5 thousands. If your going turbo you may want to increase it to around 4 to 4.5 depending on what the piston mfg says you need and how much boost you will be running for your application.

If your going to be going .20 over then the bore needs to be 3.5 over that. You will never ever do a good job with a drill and hone trying to go .023 over stock. Besides it will probably be under $200 to have it done correctly.

Just my 2 cents.

this is good advice......remember that your aftermarket pistons are more than likely forged aluminum..and aluminum expands at a different rate than your cast block...hence the clearencing issues with aftermarket pistons...allso..there is alot of reaserch you should be doing...what type of piston fits your build?...long skirts or short?...gas passageways for the comp ring?...coatings on the piston to reduce drag?..strait...taperd or barrled?...what type of pin locks are you going to order?..wire rings..or snap style?...bushingless or with bushing (bearing)?.....what alloy for the pistons?...i could go on and on...

next thing...never just overbore and call it good!...there is a way to meshure without a boreguage....they make "T" style insterments just for this...you can get a cheep set at harbor frieght for $8. bucks or so...you just colapse the tool...insert into the cylinder...release the lock to expand it..then relock and remove carefully..then meshure the top of the insterment with your micromeater.....i recomend taking at least 6 different meshurments on top of the cylinder ..in the middle and in the bottom...you should allso note what direction you are meshuring the cylinder in...write them all down and look for out of roundness...i allso recomend doing this with a torque block in place if you have one...anyways..this will set ya on the right path...good luck

[CTS13]

Damn it, i might as well go overbore then. lol. Thanx for all the advice. I was actualy just gonna order CP 9:1 pistons/rings and Eagle rods and ACL bearings. I didnt really look into all the different coatings and pistons skirt sizes.

[rioredstang]

You are going to spend good money on pistons and rods then cheap out on boring the block. Don't do it. Getting good ring seal is everything. Also rings need proper hone grit and crosshatch for break in. I would also let them check the crank and balance everything.

[liquid_cool]

Damn it, i might as well go overbore then. lol. Thanx for all the advice. I was actualy just gonna order CP 9:1 pistons/rings and Eagle rods and ACL bearings. I didnt really look into all the different coatings and pistons skirt sizes.

all you need to do is gather the information on your curent bore size and talk with your piston rep so he can order you the correct size pistons...you might allso want to read a really small book on the subject..maybe an hours read...."engine blueprinting" its a SA brand book found at any bookstore or online..you will walk away understanding more in one hour..then reading post here for days...just take your time..dont be in a rush..and plan the build bro..thinks will work out and you will have a b0mber KA under your hood for happy nissan funess!

[CTS13]

So i called the machine shop and it costs 168 bucks for a bore and hone. 235 for a line hone and all that but i dont think ill need a line hone. Eitehr way, its gonna come to less than 400 bucks to get it preped for assembly. Not bad i guess. Gonna order my pistons, rods and bearings next week.