When to bore?

[laserspeeddemon]

Was about to order my pistons, it just got me thinking do I need to bore out the cylinders. I picked up caliber and for the most part I measured 85.5x, but then I turned the caliber 90 degrees and got 85.3x-85.4x. Now since I have Manley pistons (85.5mm) they cylinders had to have been bored to 85.5mm to fit them. So now I'm confused on whether or not I am using the caliber, right.

Anywho... at what point do you bore again? Is the 0.1mm enough out of roundness to bore? What if I measured 85.6mm or 85.7mm?

A little history on the engine, built by a professional shop. Started to knock, blew head gasket, over heated. Took home, removed head, saw very slight damage from knock, decided to replace pistons. Motor has less than 10,000 miles on it.

 

[FLASH1970]

I would take it to a machine shop and get their opinion.Take the pistons and piston info with you so the machinist knows what alloy the pistons are and how much they expand and what the acceptable clearances are.

 

[laserspeeddemon]

The engine is still in the car, I have no intention of removing it unless I REALLY have to.

 

[donniekak]

Get a real dial bore gauge. Measure the bore at 3 different depths, and at 90* angles. You really don't want more than about .0004" out of round. You will also want to get a good micrometer to measure the pistons, to find the piston to cylinder wall clearance.

 

[JacksonAuto]

The engine is still in the car, I have no intention of removing it unless I REALLY have to.

You REALLY have to.

Without round cylinders you wont see any benefit of aftermarket pistons and you may as well put the stock ones back in. Will it run? Sure it will but you will sacrifice ring sealing because of the distortion of the bore. Not to mention that the surface finish is not suitable for the rings to seat properly. Two things that will lead to blowby. You also wont have the proper piston to wall clearance which will result in noise, friction and premature failure.

On a side note, a set of calipers is the wrong tool to use to measure the bores. They are not accurate enough for the job for one, and secondly they do not allow you to measure far enough into the bore. Your measurements will be significantly different at the top, middle and bottom of the cylinders. With the calipers you are only measuring the top of the cylinders, above ring travel. There will be very little wear here.

 

[3kgt2nv]

^ This

You need a dial bore gauge to see if your cylinders are out of round. And not taking it to a machine shop is ljust asking for a failure and much more expensive rebuild next time around.

 

[laserspeeddemon]

You REALLY have to.

Without round cylinders you wont see any benefit of aftermarket pistons and you may as well put the stock ones back in. Will it run? Sure it will but you will sacrifice ring sealing because of the distortion of the bore. Not to mention that the surface finish is not suitable for the rings to seat properly. Two things that will lead to blowby. You also wont have the proper piston to wall clearance which will result in noise, friction and premature failure.

On a side note, a set of calipers is the wrong tool to use to measure the bores. They are not accurate enough for the job for one, and secondly they do not allow you to measure far enough into the bore. Your measurements will be significantly different at the top, middle and bottom of the cylinders. With the calipers you are only measuring the top of the cylinders, above ring travel. There will be very little wear here.

Ok, I am on a very tight budget. The engine is 10,000 miles old if that. Could the cylinders get out round in that amount of mileage? What conditions will accelerate the out of roundess? What is the bare minimum work required to get it back running and how much would that cost for you to do it?

 

[delta448]

What is the bare minimum work required to get it back running and how much would that cost for you to do it?

Are your current pistons damaged?

At the risk of sounding like a jerk, I'll say the bare minimum would be accurately measuring the bores with the right measuring tool, as suggested, then deciding whether to bore or to hone.

Bore and hone if out-of-round as donnie noted.
"Hone alone" if you just need to break the glaze and match the PTW for your new slugs.

Either or, you still gotta pull the block, clean it and get precision measurments.

 

[laserspeeddemon]

Are your current pistons damaged?

At the risk of sounding like a jerk, I'll say the bare minimum would be accurately measuring the bores with the right measuring tool, as suggested, then deciding whether to bore or to hone.

Bore and hone if out-of-round as donnie noted.
"Hone alone" if you just need to break the glaze and match the PTW for your new slugs.

Either or, you still gotta pull the block, clean it and get precision measurments.

Yeah, I already talked to the wife about getting a hoist and engine stand. She is not happy and I am at risk of being forced to sell the Laser at this point. I already sold the Talon (thought the buyer hasn't given me the cash yet)

How thoroughly does it need to be cleaned? Do mean like hot tanked or after I bore/hone it blow the shavings off the crank, etc. What I'm trying to do is avoid removing the water pump/oil pump front case, crankshaft, etc. If I have to do that... game over, I'm out of the DSM game.

 

[JacksonAuto]

Hard to say. It could clean up and be round with just a light hone. Do that, clean everything and out it together with new ring and bearings would be a few hundred bucks. It more likely though that it will not clean up with a hone in which case you're looking at hot tanking it, deck, bor and hone. You'll also want to hot tank, mag, mic and polish the crank. For all that labor plus assembly you're looking at $800-1000 to do it right.

 

[JacksonAuto]

Yeah, I already talked to the wife about getting a hoist and engine stand. She is not happy and I am at risk of being forced to sell the Laser at this point. I already sold the Talon (thought the buyer hasn't given me the cash yet)

How thoroughly does it need to be cleaned? Do mean like hot tanked or after I bore/hone it blow the shavings off the crank, etc. What I'm trying to do is avoid removing the water pump/oil pump front case, crankshaft, etc. If I have to do that... game over, I'm out of the DSM game.

I know it's not the answer you want, but to clean it all it needs to come apart down to a bare block. There are metal ahvings in all the passages and oil galleys. The only way to get them out is to hot tank it then run rifle brushes through all of the galleys.

 

[laserspeeddemon]

Hard to say. It could clean up and be round with just a light hone. Do that, clean everything and out it together with new ring and bearings would be a few hundred bucks. It more likely though that it will not clean up with a hone in which case you're looking at hot tanking it, deck, bor and hone. You'll also want to hot tank, mag, mic and polish the crank. For all that labor plus assembly you're looking at $800-1000 to do it right.

I'm already coming up on Friday to drop off a head, I'll PM you about the rest.

 

[GRAVEDIGGER]

What I'm trying to do is avoid removing the water pump/oil pump front case, crankshaft, etc. If I have to do that... game over, I'm out of the DSM game.

Awww c'mon man.... You can't let this end the dsm game for you.
The wife will get over it. If she's anything like mine it won't be the first or the last time she's not been happy with something.

 

[laserspeeddemon]

Awww c'mon man.... You can't let this end the dsm game for you.
The wife will get over it. If she's anything like mine it won't be the first or the last time she's not been happy with something.

It's not that. My wife and I are starting a business, we are in the process of getting the loan, we met with the SBA, wrote out a business plan, met with investors, met with suppliers, found a location, met with architects, contractors, etc.

The last step is the business loan. I can't afford to have my bank account get dry, otherwise my financial standing won't look good and I won't get the business loan.
Once we get the business loan, everything goes into play. We sign the lease, the contractors start building, we start marketing, etc.


I'm not letting a car stop my wife and I's dream.

 

[GRAVEDIGGER]

I'm not letting a car stop my wife and I's dream.

By all means, don't let it stop your dreams. I'm just saying not to give up on it if it IS something you enjoy. Just put it on hold until you can work on it. Or if you DON'T enjoy it.... Give up.

Good luck with your new path.