This may sound ridiculous... Hand Honing

[Pablo]

So during my blueprinting procedure I have discovered that my piston to cylinder wall clearance is too tight. With the forged TRW pistons I have I told the machinist that I wanted a .004 to .0045 skirt to wall clearance.

After measuring the pistons with a micrometer and then measuring clearance from that with a dial bore gauge (At least 5-6 times now) I have determined that he gave me clearance generally ranging from .32 to .45 if I put the pistons in the bores he numbered them for. Mixing and matching gives me a tighter spread. I'm up to .0037 to .0044 spread from the smallest to the largest.

I really would prefer not to take this to another machine shop mostly because I hate having people do work for me, and secondly, I'd rather save money if...

..I can hand hone it out to the spec I want... is this completely out of the question? I know the typical response, but I'd like to hear from someone with actual experience or firsthand knowledge or data that shows that this is either total crap or acceptable even if I might lose 5 hp to leak down. 5 hp is not really worth the time or money to me.

 

[BEATAV8]

You could try a ball hone, available at most auto parts stores. It works with a hand drill. Old school.

 

[Nick Micale]

Doing a hand hone or ball hone will screw up the precision work and finish on the cylinder walls, assuming this was done with a "real" honing machine and sounds like it was.

If the pistons were matched to their respective cylinders, use them like that.

When we finish hone cylinders, it is an all day process as we allow the block cool down between steps. You cannot even come close with hand honing.:smile:

 

[Jerryl]

....... When we finish hone cylinders, it is an all day process as we allow the block cool down between steps. .......

Hey Nick. (Just trying to learn)

In a perfect world ..........
Would you not want to bore and hone the cylinders with the crank and torque plates installed, and at close to operating temperature as possible?

 

[Nick Micale]

Torque plate is installed during the block hone process.

No, we do not have the block at 200 or so degrees during any machine operation. It is secured to a bar in the hone machine by the main bearing caps.

 

[Pablo]

Doing a hand hone or ball hone will screw up the precision work and finish on the cylinder walls, assuming this was done with a "real" honing machine and sounds like it was.

If the pistons were matched to their respective cylinders, use them like that.

When we finish hone cylinders, it is an all day process as we allow the block cool down between steps. You cannot even come close with hand honing.:smile:

It was done with a honing machine but I think the guy did a crap job. I've measured as much as .001 of runout on some of the cylinders. I specifically told him I wanted .004-.0045 and what I got looks like a shotgun blast spread of numbers.

If I were to use the pistons in the cylinders that they were matched to, I would have one cylinder at .0032 cyl to wall clearance which I think is a sure way to scuff the cyl walls. I defer to your expertise on this though since this is my first shortblock build.

I also should run through the procedure I am using to measure this just so you guys can tell me if I am doing this wrong

First I grab the piston for a respective cylinder. I take an outside mic and very carefully measure the skirt diameter about mid way on the skirt 90 deg from the pin centerline. I try to take this measurement several times to ensure I'm measuring correctly (that I am perfectly centered)

I then lock out the micrometer at this measurement. Then I grab my dial bore gauge and I put it in between the faces of the micrometer. I very carefully center it so that I get the lowest reading. I then zero out the dial bore gauge.
From there I take the dial bore and place it into the cylinder that the piston is for. The piston clearance shows right on the gauge.

Is this the proper method? I also tried using a feeler gauge slid up the skirt of the piston with the piston installed in the cylinder. With this method I got significantly smaller piston to sidewall numbers but I believe this isn't very accurate.

Any tips or suggestions would be appreciated

 

[ChavoLC2]

Honed

Pablo you probably would be better off taking it to another machinist and have them correct redo to the specs you need.

 

[turbodave231]

If your bore/hone job was done with a deck plate you better have a deck plate on the block when you measure. Remember, the bores may not be round without the deck plate on the block (that's why we use em!).

It is very hard to measure a piston accurately and then transfer that to a bore gage. And unless you have a high precision bore gage it even gets worse. What I'm trying to say is you may be introducing error into your measurements.

Get some long strips of feeler stock in .003, .0035, .004 and .0045. Place the feeler in the bore on the major or minor thrust surface, then the piston in the bore face down. Center the piston in the bore and see how much pressure it takes to pull the feeler stock out.

Hand honing is not accurate and poor way to increase your clearance. The bores may not be round when you're done.

 

[Pablo]

If your bore/hone job was done with a deck plate you better have a deck plate on the block when you measure. Remember, the bores may not be round without the deck plate on the block (that's why we use em!).

It is very hard to measure a piston accurately and then transfer that to a bore gage. And unless you have a high precision bore gage it even gets worse. What I'm trying to say is you may be introducing error into your measurements.

Get some long strips of feeler stock in .003, .0035, .004 and .0045. Place the feeler in the bore on the major or minor thrust surface, then the piston in the bore face down. Center the piston in the bore and see how much pressure it takes to pull the feeler stock out.

Hand honing is not accurate and poor way to increase your clearance. The bores may not be round when you're done.

I can vouch for measuring the bores being difficult. It is a real pita and very tedious. I have tried my best to eliminate any possible inaccuracies outside of an inaccuracy in the tool which I dont believe to be an issue.
So far I have been able to achieve consistent enough results though to convince me I am getting reasonably accurate numbers. I will go through them again here in a little bit using a slightly different method just to check for the 15th time or so

I do have shim stock on hand in .003 thickness. Since all of my bores are over .003 I should be able to pull it out easily correct?

By the way, I have found some interesting information on hand honing online. Apparently results that are just as good or better than machine honing can be accomplished with a skilled operator and the proper equipment. All the sources talk about sunnen portable equipment and various stones, sunnen oil, etc. Unfortunately the sunnen hone for this purpose is like almost 400 dollars. Haven't found anything specific to the cheap glaze breakers you can buy anywhere other than a few buildups using them just to refinish good but glazed cylinders.

 

[gnxtc2]

Hot hone = $$$$$$$

If you are checking the machine shop's work, then you must install the torque plate to measure. Also, you are measuring with two different dial bore gauges.

Billy T.
gnxtc2@aol.com

 

[Pablo]

Hot hone = $$$$$$$

If you are checking the machine shop's work, then you must install the torque plate to measure. Also, you are measuring with two different dial bore gauges.

Billy T.
gnxtc2@aol.com

Do you mean to say that I need to use two different dial bore gauges to be sure my measurements are correct?

I just went out and measured again and got the same result with the dial bore.. too tight. Actually its tighter if i measure at the bottom of the skirt on the pistons. They seem to be slightly wider there. I'm down below .003 with that measurement.

To back up that measurement I used .003 shim stock and tried the method outlined by turbodave. I cant get the piston to go all the way in, and the shim stock does not want to come out when its in there.

No this was not honed with a torque plate. Though this would be a debate for another post I question the usefulness of the torque plate for our application. No one on the pro side seems to have any actual measurements to support their arguments. Just second hand information. The only person who has actually measured bore distortion with the heads on (that has posted on this forum) could not find any appreciable bore distortion at all and he honed without a deck plate. I also don't think you can totally account for the differing rates of thermal expansion of the bolts, the hotter side of the chamber, the top being hotter than the bottom, cyl distortion from the insane cylinder pressure during actual engine operation, and actual combustion chamber temps transferring to the top of the bore (would be a lot warmer than 200 deg water)
Of course these are all just my own theories at this point since I have not actually tested this. I could bolt my heads on and check bore distortion for myself but the rest of the variables cant be practically checked. If anyone has -no bs- measured this and has data to show one way or another I would really be glad to hear it. Also, I've always figured that the power is in the airflow side of the house. It seems to me that you can spend 10 grand on a shortblock and only make marginally more power than a 2 grand shortblock with the same heads/cam etc. Sure you might throw away 25 hp in leak down but that 25 hp in leakdown will cost you an arm and a leg to get. Would make more sense to put that into cylinder heads, cam, or something else that gave you more bang for the buck.
Anyway I'm sure a lot of people probably think I am a moron for typing this and I may be one. I just like to see the numbers add up.

 

[S2V6RACER]

Do you mean to say that I need to use two different dial bore gauges to be sure my measurements are correct?

I just went out and measured again and got the same result with the dial bore.. too tight. Actually its tighter if i measure at the bottom of the skirt on the pistons. They seem to be slightly wider there. I'm down below .003 with that measurement.

To back up that measurement I used .003 shim stock and tried the method outlined by turbodave. I cant get the piston to go all the way in, and the shim stock does not want to come out when its in there.

No this was not honed with a torque plate. Though this would be a debate for another post I question the usefulness of the torque plate for our application. No one on the pro side seems to have any actual measurements to support their arguments. Just second hand information. The only person who has actually measured bore distortion with the heads on (that has posted on this forum) could not find any appreciable bore distortion at all and he honed without a deck plate. I also don't think you can totally account for the differing rates of thermal expansion of the bolts, the hotter side of the chamber, the top being hotter than the bottom, cyl distortion from the insane cylinder pressure during actual engine operation, and actual combustion chamber temps transferring to the top of the bore (would be a lot warmer than 200 deg water)
Of course these are all just my own theories at this point since I have not actually tested this. I could bolt my heads on and check bore distortion for myself but the rest of the variables cant be practically checked. If anyone has -no bs- measured this and has data to show one way or another I would really be glad to hear it. Also, I've always figured that the power is in the airflow side of the house. It seems to me that you can spend 10 grand on a shortblock and only make marginally more power than a 2 grand shortblock with the same heads/cam etc. Sure you might throw away 25 hp in leak down but that 25 hp in leakdown will cost you an arm and a leg to get. Would make more sense to put that into cylinder heads, cam, or something else that gave you more bang for the buck.
Anyway I'm sure a lot of people probably think I am a moron for typing this and I may be one. I just like to see the numbers add up.

Each to their own, but my leak down numbers tell me my engine builder is doing something right.....

 

[gnxtc2]

Do you mean to say that I need to use two different dial bore gauges to be sure my measurements are correct?

You have a differrent gauge than the guy that honed the block. There might be difference/tolerances between the two gauges.

I just went out and measured again and got the same result with the dial bore.. too tight. Actually its tighter if i measure at the bottom of the skirt on the pistons. They seem to be slightly wider there. I'm down below .003 with that measurement.

To back up that measurement I used .003 shim stock and tried the method outlined by turbodave. I cant get the piston to go all the way in, and the shim stock does not want to come out when its in there.

No this was not honed with a torque plate. Though this would be a debate for another post I question the usefulness of the torque plate for our application. No one on the pro side seems to have any actual measurements to support their arguments. Just second hand information. The only person who has actually measured bore distortion with the heads on (that has posted on this forum) could not find any appreciable bore distortion at all and he honed without a deck plate. I also don't think you can totally account for the differing rates of thermal expansion of the bolts, the hotter side of the chamber, the top being hotter than the bottom, cyl distortion from the insane cylinder pressure during actual engine operation, and actual combustion chamber temps transferring to the top of the bore (would be a lot warmer than 200 deg water)
Of course these are all just my own theories at this point since I have not actually tested this. I could bolt my heads on and check bore distortion for myself but the rest of the variables cant be practically checked. If anyone has -no bs- measured this and has data to show one way or another I would really be glad to hear it. Also, I've always figured that the power is in the airflow side of the house. It seems to me that you can spend 10 grand on a shortblock and only make marginally more power than a 2 grand shortblock with the same heads/cam etc. Sure you might throw away 25 hp in leak down but that 25 hp in leakdown will cost you an arm and a leg to get. Would make more sense to put that into cylinder heads, cam, or something else that gave you more bang for the buck.
Anyway I'm sure a lot of people probably think I am a moron for typing this and I may be one. I just like to see the numbers add up.

My engine builder uses a torque plate when he hones the blocks. When he line hones the mains, he bolts the heads on the block.

Do yourself a favor, bolt the heads on the block then take your measurements. You will see that the cylinders have distorted themselves.

Billy T.
gnxtc2@aol.com

 

[Pablo]

You have a differrent gauge than the guy that honed the block. There might be difference/tolerances between the two gauges.




My engine builder uses a torque plate when he hones the blocks. When he line hones the mains, he bolts the heads on the block.

Do yourself a favor, bolt the heads on the block then take your measurements. You will see that the cylinders have distorted themselves.

Billy T.
gnxtc2@aol.com

I will check it against my micrometer and also swap out to a different dial indicator just to be sure. Thanks for the tip.

As for the torque plate, not trying to be a smart ass here but, have you measured it? If you have, save me the time of doing it myself and let me know how much the cylinders distorted. I'll take you for your word. I understand that many engine builders use one and I believe this is well intentioned, but I also believe that people are trying to "upsell" so many things in the turbo buick world that I'd like to see the numbers. Also, please include whether or not you had the mains and or girdle torqued down when you did this. According to Vizard et al. the mains typically distort the block more than the heads. Ill see about giving it a try if no one has any measurements.

 

[Pablo]

http://www.turbobuick.com/forums/ge...h/149265-first-time-rebuild-torque-plate.html

Ttype6 brings up some interesting points regarding the torque plate.

 

[87GN_70GS]

Have you had your micrometer calibrated? He probably has a good US made set and at some time or another was cal'd. Same for the dial bore gauge. Temperature also makes a difference. All pieces need to be at the same temp and also have been at that temp for awhile. Are you measuring at the point on the skirt spec'd by the piston manufacturer?

 

[Pablo]

Have you had your micrometer calibrated? He probably has a good US made set and at some time or another was cal'd. Same for the dial bore gauge. Temperature also makes a difference. All pieces need to be at the same temp and also have been at that temp for awhile. Are you measuring at the point on the skirt spec'd by the piston manufacturer?

Well the micrometers calibration doesn't really play a part in the determination of bore clearance. When you set the micrometer to the O.D. of the piston skirt you just lock it and regardless of the reading on the micrometer the dial bore is then placed in between the micrometer faces and set at zero. Regardless of that, I have checked the micrometer against some standards that I have and the micrometer is accurate if the standards are accurate.
When I measure the bore clearance I was measuring half way up the skirt 90 deg from the pin bore axis. But I have since concluded that the pistons are actually a little wider at the bottom of the skirt so I think that might be a better place to measure them at.
As for the dial indicator on the dial bore gauge, I have not checked that it is measuring in a linear fashion (actually i have everything written down so i can just double check the numbers) but I will. From what I understand they don't really go out of calibration per se but will start to get some hysteresis in the readings (i.e. a bigger number going up than when going down) that doesn't seem to be happening. But like I said I will definitely swap to another micrometer I have here.

 

[ijames]

Pablo, I think that the only way you will know for sure about your block is to torque the heads on and measure the bore at a couple of distances from the deck. Actually, measure parallel and perpendicular to the crank to get an idea on roundness. Then compare with the same measurements with heads off. Check with trw to get their instructions on exactly where to measure on the pistons.

 

[forcedfedv6]

TRW pistons should have a clearance of .0045 to .0050 but no more, call TRW and ask what they recomment but i am sure thats what it is.. also one mistake that people make with too loose clearance and driveability is that as soon as they start the car is the morning they go out and do A WOT blast which is the worst thing you can do to cold pistons and cylinder walls ,that's how you end up scorching the side of the rings with the skirts which is normally called piston slap this is due to the piston being cold and having too much clearance at start up, the piston has to reach a certain temp to swell to the right clearances..

 

[Pablo]

the data sheet with the pistons calls for a .0035 clearance only and to just measure perpendicular to the pin bore.

Obviously .0035 is too tight for a high perf. turbo setup. Thanks for the tip forcefed. I was thinking about going looser than my 004-0045 just to be safe. Good to hear I can.