Help me determine my piston-to-head clearance!

[wed3k]

i believe you're missing the wrist pin weight

[GhostAccord]

i believe you're missing the wrist pin weight

I didn't add in rings or bearing weights ether. I didn't really see the point when comparing piston and rod weights! Are you saying that the wrist pins and rings are going to be that much different between manufacturers?

Here is my complete rod and piston assembly.....

976 grams @ 16.5°C..... including wrist pin, clips, rings, rod bolts and bearings.

[SOHC-FTW]

I don't see rod bolts or the oil ring rails just see the oil expansion ring.... redo damnit ha!

To address the OP i know some company on ebay used to sell cooper high and low compression head gaskets for around $90+ i think i seen a f22b/f23 2mm on there a good while back.

[wed3k]

I didn't add in rings or bearing weights ether. I didn't really see the point when comparing piston and rod weights! Are you saying that the wrist pins and rings are going to be that much different between manufacturers?

Here is my complete rod and piston assembly.....

976 grams @ 16.5°C..... including wrist pin, clips, rings, rod bolts and bearings.

different diameter wrist pins obviously yields different weights. for a NA application where you aren't making gobs of power, id rather sacrifice a little bit of durability for weight.

ive seen quality pistons where the wrist pin is really narrow and also tapered for strength.

[GhostAccord]

I looked at a set of light weight chamfered Ti wrist pins that were lighter than mine. I'm really not willing to go any thinner on the wall thickness than the 63 gram pins that they quoted me. @ $180 a piece the weight savings isn't quite worth it ......

I'm not 1/4 mile racing to pay the bills. Shaving 27 grams is not worth $720 for a set of wrist pins. Most guys around here won't even pay $550 for custom pistons.......

[Jarrett]

I could spend less and get better results by reducing valvetrain mass before I'd plop that much on the table for wristpins.

[ON_N20]

$210 is a hefty price to pay to have a set of brand new pistons machined. To be honest, I would have sold them and bought new ones.... Probably would have saved yourself $150-$200.

Anyway back on topic , the machinest called today and the pistons are done. My cost is less than $200 in the end. They would have been done on saturday as I planned but he needed the other piston jig to hold them. I'll be picking them up wednesday and hopefully can post pics if I can locate my camera.

The reason I opted to machine my current pistons is because:
A: I have perfectly good pistons currently other than the fact they now extend the block, machining them costs me far less money, and time, than waiting for new pistons.
B: Yes, I could sell the pistons I have now, and buy new custom pistons, netting my total cost most likely more than $200, however mainly I dont want to hinge my entire engine build to wait for someone to hopefully buy my used set of pistons here in south central wisconsin. It very well could be winter by then IF they sell, and in the event they dont, I cant just bite it and shell out another $500 to get new pistons, Im at the end of my budget with a house and bills to pay for.

As for piston rock, I mentioned that already and no one seemed to take any interest in it. Guess all it takes is having to spend extra money to fix an issue for people to realize what it takes to build an engine.

Hopefully everything will work out for you now.

I appreciate your input, and I apologize for not catching what you posted earlier regarding the piston rock. I was aware that there would be some piston rock at the time, but did not realize that it could be measured properly and calculated in the final equation to find my clearance number. Now that I know this, if there is a next time around I am prepared better with this knowledge.

[Youngill726]

So are you happy with your decision? I dont think I could cut my pistons. I decided to go with a thicker headgasket from cometic once I figure what size I will need. I would sell the pistons but couldn't be sure how long it would take to sell them but I'm only .018 out the block but still enough to mess with compression. I don't know as much as you guys do and nor am I that mechanically inclined. I know a little over the basics but am learning from my mechanic. What's does piston rock affect?

[wed3k]

piston to head clearance.

i don't like copper headgaskets. good for cylinder sealing especially if the sleeves are o-ringed but ive heard of oil drain and coolant sealing issues.

[toycar]

piston to head clearance.

i don't like copper headgaskets. good for cylinder sealing especially if the sleeves are o-ringed but ive heard of oil drain and coolant sealing issues.

Ive personally experienced this.


And its bullshit BTW. They are awesome when they work correctly, but, well honestly its a big fucking hassle to rip the motor apart for no damn reason other then this.

[wed3k]

Ive personally experienced this.


And its bullshit BTW. They are awesome when they work correctly, but, well honestly its a big fucking hassle to rip the motor apart for no damn reason other then this.

especially in a car thats difficult to remove the head.

my shop just finished building a volvo s60 r motor and the only option was a copper head gasket. i hope that shit don't leak but we used good silicone to seal everything.

[toycar]

especially in a car thats difficult to remove the head.

my shop just finished building a volvo s60 r motor and the only option was a copper head gasket. i hope that shit don't leak but we used good silicone to seal everything.

I cringed at volvo....

I cannot believe they shoe horn that motor in there like they do

[ON_N20]

So are you happy with your decision? I dont think I could cut my pistons. I decided to go with a thicker headgasket from cometic once I figure what size I will need. I would sell the pistons but couldn't be sure how long it would take to sell them but I'm only .018 out the block but still enough to mess with compression. I don't know as much as you guys do and nor am I that mechanically inclined. I know a little over the basics but am learning from my mechanic. What's does piston rock affect?

Yes I'm happy with my decision, the pistons look fantastic, the machinework was great. It was a little hard at first to fatham the tought of machining my pistons untill I realized after talking with the machinest that its a pretty common practice under circumstances such as mine. They pretty much look identical as they did before but with .030" taken off the outer upper edge, and the valve relief's deepened the same amount.

Now, when I got home, I figured before assembling my engine again that it would be wise to figure out my new actual compression ratio. I bought myself a graduated cylinder and an syringe and measured the new volume of the piston top, and the combustion chamber, and along with other measurements and the help of a CR calculator, I came up with a new compression ratio of 9.22:1. Before my compression ratio would have been 8.2:1. So between machining the block, piston and head, I gained 1 CR point. 9.2:1 will still be easy to boost, although I anticipate I will have to modify my tune when I get everything running again.

Also to answer your question about what piston rock affects:

Imagine your piston sitting at true top dead center, as high as the piston will ever reach (excluding temp. expansion and stretch) - the amount of space between that highest point on the piston and the block is your piston-to-head clearance, also called squish or quench. Too much space can cause poor performance and detonation, to little space and contact between the piston and head can occur = BAD. You can measure piston-to-head clearance. Piston rock comes into play because every piston can rock side to side to some degree (side to side as in parallel to the piston pin axis). Imagine the top of your piston as a teter totter - as it rocks one way or another, the height on side one will rise as the other falls, and the height at the highest point can never be exceeded from there. If you measure your piston rock at the highest and at the lowest point, then you can know exactly how high your piston will ever reach, and you can then determine the exact piston-to-head clearance you have, and you can decide where to set piston-to-head clearance (for instance if you were waiting to order a custom thickness head gasket).

BTW, Here is today's progress!

[ON_N20]

i don't like copper headgaskets. good for cylinder sealing especially if the sleeves are o-ringed but ive heard of oil drain and coolant sealing issues.

I agree. Copper head gaskets are great ONLY if the block is made to accept them, which means having it o-ringed like you said. Some people will use copper head gaskets and use sealing compounds to attempt to create a lasting seal, but most of the time it will fail with time. Not to mention the Honda F22A and F22B sohc blocks are an open-deck design with very little cylinder material at the top seperating the combustion chamber from the coolant passage. I would imagine that would be the first failure point if a copper head gasket were to be used in those engines.

[wed3k]

Yes I'm happy with my decision, the pistons look fantastic, the machinework was great. It was a little hard at first to fatham the tought of machining my pistons untill I realized after talking with the machinest that its a pretty common practice under circumstances such as mine. They pretty much look identical as they did before but with .030" taken off the outer upper edge, and the valve relief's deepened the same amount.

Now, when I got home, I figured before assembling my engine again that it would be wise to figure out my new actual compression ratio. I bought myself a graduated cylinder and an syringe and measured the new volume of the piston top, and the combustion chamber, and along with other measurements and the help of a CR calculator, I came up with a new compression ratio of 9.22:1. Before my compression ratio would have been 8.2:1. So between machining the block, piston and head, I gained 1 CR point. 9.2:1 will still be easy to boost, although I anticipate I will have to modify my tune when I get everything running again.

Also to answer your question about what piston rock affects:

Imagine your piston sitting at true top dead center, as high as the piston will ever reach (excluding temp. expansion and stretch) - the amount of space between that highest point on the piston and the block is your piston-to-head clearance, also called squish or quench. Too much space can cause poor performance and detonation, to little space and contact between the piston and head can occur = BAD. You can measure piston-to-head clearance. Piston rock comes into play because every piston can rock side to side to some degree (side to side as in parallel to the piston pin axis). Imagine the top of your piston as a teter totter - as it rocks one way or another, the height on side one will rise as the other falls, and the height at the highest point can never be exceeded from there. If you measure your piston rock at the highest and at the lowest point, then you can know exactly how high your piston will ever reach, and you can then determine the exact piston-to-head clearance you have, and you can decide where to set piston-to-head clearance (for instance if you were waiting to order a custom thickness head gasket).

BTW, Here is today's progress!

hell id rather start at 9:1 before 8:1 any day of the week. it makes daily driving so muchbetter.