Chuck's Engine Build

[cdigerlando]

I checked the crank. It is out about 0.0005 at 7 & 6 and a slight movement on Journal 3. The rest are not measureable. The dial guage I used measures up to 15 thousands per revolution, so the resolution between thousands is pretty high. Almost as high as the original dial guage where I measured about 0.75 thousands. I also checked this on a second gauge.

I was unable to double check the bores. Was supposed to do that today but got sidetracked with my son. Harry's bore guage was not set up (brand new). He was going to have one of the guys at his shop set it up this week. I don't want to bolt it up and find out I have a problem with the bores. As I said before the shop said they bored it to 0.004. This should put the bore diameter at about 3.823 if it was done correctly.

[longassname]

Did you check for round first? The numbers sound more like out of round than a bend.

Your bore should definitely not be 3.823 if done correctly. You added an extra 4 thou to what the bore should be there instead of to what the piston should be. Your bores should be right around 3.819. Whatever it is you'll find some fluctuation in it. You want to write down your measurements and take them as follows:

measure each bore relatively close to the top but not the tipy top
repeat that measurement 90 degrees off to check for round
measure each bore close to the bottom to check for taper

Unlike most automotive engines the cyllinders are blind holes on subaru engines which makes them dificult to hone for someone not experienced in honing blind holes. That means to take your looking for taper seriously; many machine shops will mess this up. (A tip for others: machine shops that do outboard boat engines are used to honing blind holes)

After you have your actual bore measurements you want to measure your pistons with an outside micrometer. Because you have my pistons you will find they all measure within a ten of each other (ie + or - .00005") but still you can put the bigger ones in the bigger cyllinders and the smaller ones in the smaller cyllinders and at any rate subtracting the piston diameter from the bore tells you your sidewall clearance. (it's a safe bet anything beyond 3.8200 is bad)

Originally Posted by cdigerlando

I checked the crank. It is out about 0.0005 at 7 & 6 and a slight movement on Journal 3. The rest are not measureable. The dial guage I used measures up to 15 thousands per revolution, so the resolution between thousands is pretty high. Almost as high as the original dial guage where I measured about 0.75 thousands. I also checked this on a second gauge.

I was unable to double check the bores. Was supposed to do that today but got sidetracked with my son. Harry's bore guage was not set up (brand new). He was going to have one of the guys at his shop set it up this week. I don't want to bolt it up and find out I have a problem with the bores. As I said before the shop said they bored it to 0.004. This should put the bore diameter at about 3.823 if it was done correctly.

[cdigerlando]

Originally Posted by longassname

Did you check for round first? The numbers sound more like out of round than a bend.

Your bore should definitely not be 3.823 if done correctly. You added an extra 4 thou to what the bore should be there instead of to what the piston should be. Your bores should be right around 3.819. Whatever it is you'll find some fluctuation in it. You want to write down your measurements and take them as follows:

measure each bore relatively close to the top but not the tipy top
repeat that measurement 90 degrees off to check for round
measure each bore close to the bottom to check for taper

Unlike most automotive engines the cyllinders are blind holes on subaru engines which makes them dificult to hone for someone not experienced in honing blind holes. That means to take your looking for taper seriously; many machine shops will mess this up. (A tip for others: machine shops that do outboard boat engines are used to honing blind holes)

After you have your actual bore measurements you want to measure your pistons with an outside micrometer. Because you have my pistons you will find they all measure within a ten of each other (ie + or - .00005") but still you can put the bigger ones in the bigger cyllinders and the smaller ones in the smaller cyllinders and at any rate subtracting the piston diameter from the bore tells you your sidewall clearance. (it's a safe bet anything beyond 3.8200 is bad)

I noticed in your thread that your bores match what you just told me, however, when I measured the piston skirt, I came up with 3.819" which is close to 97.0 mm, which is what I thought the listed diameter of the piston was. When Harry measured the piston bores with a telescopic gauge, he came up with measurements at 3.818 to 3.822. A lot of out of round and a lot of some difference between top and bottom. Not very repeatable. We were using a telescopic gauge and vernier caliper to measure. I don't really trust the telescopic gauge, so we'll be using a bore gauge next time. If the bores don't work out I will take it back.

If I had to go with a coating, about how much does this typically add to the piston diameter?

[longassname]

Yikes that sounds aweful but ya you won't get good measurements with a telescopic gage. I would guess all that fluctuation in measurements is from the measuring not the machining. Who's Harry? Your machinist doesn't have the tools to measure your bores? How did he hone them?

Sounds like you need to work on your outside micrometer skills/tools too--there is no way your piston skirts measure that. Feel free to call if you need assistance.

Originally Posted by cdigerlando

I noticed in your thread that your bores match what you just told me, however, when I measured the piston skirt, I came up with 3.819" which is close to 97.0 mm, which is what I thought the listed diameter of the piston was. When Harry measured the piston bores with a telescopic gauge, he came up with measurements at 3.818 to 3.822. A lot of out of round and a lot of some difference between top and bottom. Not very repeatable. We were using a telescopic gauge and vernier caliper to measure. I don't really trust the telescopic gauge, so we'll be using a bore gauge next time. If the bores don't work out I will take it back.

If I had to go with a coating, about how much does this typically add to the piston diameter?

[cdigerlando]

Originally Posted by longassname

Yikes that sounds aweful but ya you won't get good measurements with a telescopic gage. I would guess all that fluctuation in measurements is from the measuring not the machining. Who's Harry? Your machinist doesn't have the tools to measure your bores? How did he hone them?

Sounds like you need to work on your outside micrometer skills/tools too--there is no way your piston skirts measure that. Feel free to call if you need assistance.

In all likelyhood my machinist probably did a better job measuring all of this stuff than I did. Harry is a Nasioc member, and a pretty high level engineer in Central Florida. He has a lot of good measurement tools, but we engineers don't really use them that much. I trust a good practiced machinist for measurment better than myself.

I worked on a new technique to get around the piston and into the bores. Everything is looking pretty good. 3.816 on the pistons, about 3.8195 on the bores. I still want to check the bores with a bore caliper though so I can get top and bottom measurments.

[longassname]

The best way to use an outside micrometer on something cyllindrical like your pistons is to (after zeroing it on a certified standard) set it to what you think the measurement should be and lock it at that setting (alternatively close the micrometer on the piston until the ratchet clicks then back it off about 5 tens and lock it). Then try to slip it around the piston. If the piston is larger than what you have the micrometer set at it won't go if it's smaller it will. It's easiest to work from the direction of having the micrometer set too big so in short what you are doing is getting the micrometer set just a little too big as your starting point. From there close it down one ten and lock it and try again repeating until it won't slide around the piston and then backing it off half a ten and locking it. If it slides over the piston then you have your measurement if not back it off another half ten. This method will give you the correct measurment including the guesstimate digit (the fraction of a ten)for scientific notation.

Originally Posted by cdigerlando

In all likelyhood my machinist probably did a better job measuring all of this stuff than I did. Harry is a Nasioc member, and a pretty high level engineer in Central Florida. He has a lot of good measurement tools, but we engineers don't really use them that much. I trust a good practiced machinist for measurment better than myself.

I worked on a new technique to get around the piston and into the bores. Everything is looking pretty good. 3.816 on the pistons, about 3.8195 on the bores. I still want to check the bores with a bore caliper though so I can get top and bottom measurments.

[longassname]

oh ...

just fyi The reason for the locking in the methodology is otherwise the thimble turns on you while you are sliding the micrometer around the piston.

[SVXRide]

Good stuff...brings back memories of my early days working in a Navy machine shop
-Bill

[cdigerlando]

I finally got a good bore gauge. I found a couple of issues. One I have a spot at the top of one of my cylinders about 25 tens deep. The piston was honed out to a clearance of about 37 tens, so I don't want to go much more. I would rather not scrap the block, but I also don't want to take a chance that this would be a problem in the future. I'm thinking about doing a swain heavy skirt coating which adds about 40 tens to the diameter. This might not even be enough to hone out this spot though, so I may need to go to 45 tens total clearance with the coating. This would mean honing another 50 tens clearance. I'm going to talk to my machine shop and see if they will let me camp out next to the CNC machine with my bore gauge.

Also my other bores varied from 15 to 25 tens clearance. I would prefer to have them all closer to 35 tens. Also the cylinder that was bored to 37 tens showed a lot better roundness and less taper. One cylinder I measured did not meet subaru's taper tolerance, so it definitely needs more work.

This would leave me a bit lopsided though. I don't know if I should just coat one piston or do all of them. If I do all of them, I'll have to see if one of you guys wants to trade my cut rings for your uncut rings. Could save you the bother of doing it. It's basically set up to run the same clearances that Mike ran with a 35 tens clearance. Slightly smaller would probably not matter much.

Another option that I am considering is sleaving. I have a call into AR fabrication to see how much that would cost. They typically charge about 1850 for a 4 cylinder so I'm thinking for a 6 cylinder he is probably going to charge me after honing and decking about $3000. I'm not too happy about that.

I know that when I talk to chris about the spot he is not going to think it is a problem, however I just don't want to take the chance. I'm also not too happy about the taper in the bores.

Fun fun stuff.

[longassname]

Got any pictures? The quality of the machine work doesn't sound very impressive so far so I'd be interested in seeing the cyllinder finish. I'd also be interested in seeing what this spot you are talking about is.

cnc machine? He's not using a real honing machine?

Originally Posted by cdigerlando

I finally got a good bore gauge. I found a couple of issues. One I have a spot at the top of one of my cylinders about 25 tens deep. The piston was honed out to a clearance of about 37 tens, so I don't want to go much more. I would rather not scrap the block, but I also don't want to take a chance that this would be a problem in the future. I'm thinking about doing a swain heavy skirt coating which adds about 40 tens to the diameter. This might not even be enough to hone out this spot though, so I may need to go to 45 tens total clearance with the coating. This would mean honing another 50 tens clearance. I'm going to talk to my machine shop and see if they will let me camp out next to the CNC machine with my bore gauge.

Also my other bores varied from 15 to 25 tens clearance. I would prefer to have them all closer to 35 tens. Also the cylinder that was bored to 37 tens showed a lot better roundness and less taper. One cylinder I measured did not meet subaru's taper tolerance, so it definitely needs more work.

This would leave me a bit lopsided though. I don't know if I should just coat one piston or do all of them. If I do all of them, I'll have to see if one of you guys wants to trade my cut rings for your uncut rings. Could save you the bother of doing it. It's basically set up to run the same clearances that Mike ran with a 35 tens clearance. Slightly smaller would probably not matter much.

Another option that I am considering is sleaving. I have a call into AR fabrication to see how much that would cost. They typically charge about 1850 for a 4 cylinder so I'm thinking for a 6 cylinder he is probably going to charge me after honing and decking about $3000. I'm not too happy about that.

I know that when I talk to chris about the spot he is not going to think it is a problem, however I just don't want to take the chance. I'm also not too happy about the taper in the bores.

Fun fun stuff.

[cdigerlando]

Originally Posted by longassname

Got any pictures? The quality of the machine work doesn't sound very impressive so far so I'd be interested in seeing the cyllinder finish. I'd also be interested in seeing what this spot you are talking about is.

cnc machine? He's not using a real honing machine?

I'm probably not using the correct wording for his equipment.

The finish looks good. I'll take pics before I put it together.

Looking at the numbers it is obvious to me that the cylinders needed much more honing due to the engine's age. The greater the clearance honed, the better the roundness and taper of the bore. Well within spec. The question is how much honing will I need to do to smooth out my corrosion pit. I won't know that until I hone the cylinder. I'm hoping that the skirt coating will increase the diameter of the piston enough and require a large enough bore to open up this area. From the numbers I saw looking at the bores, I'm confident that his machine is true. I will pick my largest diameter piston following coating and use this in my problem cylinder 3. Hopefully the new required diameter will not require too much clearance. With the skirt coated piston I may actually not go with 35 tens clearance if I can help it. I may keep the clearance somewhere closer to 20 or 25 tens with this coating on the piston. I don't think that would be enough boring though, based on the pit depth. Whatever I need to take off around the pit I have to take off the other side so the numbers would double. So for 25 tens of pit I would need to take off 50 tens of diameter. Since I am only adding 40 tens of diameter from the coating, and already have 37 tens of clearance I may be short of my goal.

[longassname]

Maybe it would be easier to use different pistons with this block or a different block with these pistons.

Originally Posted by cdigerlando

I'm probably not using the correct wording for his equipment.

The finish looks good. I'll take pics before I put it together.

Looking at the numbers it is obvious to me that the cylinders needed much more honing due to the engine's age. The greater the clearance honed, the better the roundness and taper of the bore. Well within spec. The question is how much honing will I need to do to smooth out my corrosion pit. I won't know that until I hone the cylinder. I'm hoping that the skirt coating will increase the diameter of the piston enough and require a large enough bore to open up this area. From the numbers I saw looking at the bores, I'm confident that his machine is true. I will pick my largest diameter piston following coating and use this in my problem cylinder 3. Hopefully the new required diameter will not require too much clearance. With the skirt coated piston I may actually not go with 35 tens clearance if I can help it. I may keep the clearance somewhere closer to 20 or 25 tens with this coating on the piston. I don't think that would be enough boring though, based on the pit depth. Whatever I need to take off around the pit I have to take off the other side so the numbers would double. So for 25 tens of pit I would need to take off 50 tens of diameter. Since I am only adding 40 tens of diameter from the coating, and already have 37 tens of clearance I may be short of my goal.

[cdigerlando]

Originally Posted by longassname

Maybe it would be easier to use different pistons with this block or a different block with these pistons.

The thought of getting a new block crossed my mind. Hence why I asked my machinist to do number 3 first before semi closing the deck. I think I'll be OK with the coating though.

Different pistons? Who sells them?

Anyone want to trade uncut rings for my precut rings? Would save you time and save me money. If there is an issue I would be happy to compensate, but they are set to run at 35 tens. If you run less clearance you would just have to file a little more.

Mike how much for a 6 new set of rings?

[longassname]

Chuck how did you file your rings without your bores being done first?


To get the sameish pistons for a larger bore we'd have to order them. If you wanted to run more compression I have the 9.3 CR pistons coming in soon though I think there are a couple of other people who want them too.

I'll have to check on the price for rings.

[cdigerlando]

Originally Posted by longassname

Chuck how did you file your rings without your bores being done first?


To get the sameish pistons for a larger bore we'd have to order them. If you wanted to run more compression I have the 9.3 CR pistons coming in soon though I think there are a couple of other people who want them too.

I'll have to check on the price for rings.

Apparently he filed them using number 3 bore as a guide. When I checked them so they are running less gap with the smaller bore diameters. They came out right around the same clearance as yours. Basically he said that they were all the same bore diameter so it would not matter.

Buying new rings at this point seems like a waste, but unless any of the guys who bought pistons want to trade, I will be stuck with them. It would be better for them since they are cut to fit the 37 tens bore, with the same clearances you used.

I'm not thinking about new pistons. I would sleeve the motor before I would do that.