piston fit

[Jim Allen]

"Jim in the ops bi metal are you saying the outer aluminum on the sleeve is maybe a stabilizer temp wise - holds it at a certain temp- as it heats(brass) the aluminum dissipates holding it? thermal imaging would be extremely useful in analyzing whats going on."

I don't know & maybe OPS didn't know. Looks really sharp though. Maybe it was done in an attempt to cool the incomming charge even though it would be in contact for less than a few micro seconds.

 

[dwilfong]

I had a chance to use the flex hone and it is the bomb.

I had the privilege of having a few cylinders honed by Stu Barr and this flex hone leaves a comparable finish.

The piston slides to the pinch with a smooth as silk feel then just stops.

We will see how it goes after a few tanks.

David

 

[Terry Keeley]

Just found out the material I made pistons from was Dispal S226 (30% Si).

Any comments on this material?

http://www.matweb.com/search/DataSheet.aspx?MatGUID=08beb0681bd04fe8896e8f645d113ac9&ckck=1

 

[Jim Allen]

I never used this alloy, but many of the dispal alloys that can be used for pistons require heat treating before final machining.

 

[Terry Keeley]

I never used this alloy, but many of the dispal alloys that can be used for pistons require heat treating before final machining.

Thanks Jim, found this on a German C/L site, they talk about stabilizing the material:

http://www.control-l...n/index_en.html

(click link to Google translation)

 

[dwilfong]

I had the privilege of spending a day with Mart Davis in the shop. he showed me a liner pincher that was made with a tapper cut into it.

He used it on one of my RS7 sleeve. he would turn the liner to preset marks on the jig using the centering pin notch as a reference. he used a torque wrench to tighten it at every mark.

He said this would give a .002 taper from the top of the ex to the top of the liner.

I still run this sleeve with new piston from CMB and it holds the pinch for a very long time.

The only reason I have changed pistons one time was the skirt broke at the bottom of the ex side.

For those of use that can't make are own liners we are stuck with what ever the factory gives us.

Now this specialized pincher dose give a chance to try different tappers.

But building one is probably just as involved as making the sleeve.

David

harder to make than a straight one.just have to mount the block in a lathe and cut the bore with the compound

Tried what you said and made a squeezer today .004 taper over 1/2" . Gave it a try and it works nice.

 

[Gator 340]

I had the privilege of spending a day with Mart Davis in the shop. he showed me a liner pincher that was made with a tapper cut into it.

He used it on one of my RS7 sleeve. he would turn the liner to preset marks on the jig using the centering pin notch as a reference. he used a torque wrench to tighten it at every mark.

He said this would give a .002 taper from the top of the ex to the top of the liner.

I still run this sleeve with new piston from CMB and it holds the pinch for a very long time.

The only reason I have changed pistons one time was the skirt broke at the bottom of the ex side.

For those of use that can't make are own liners we are stuck with what ever the factory gives us.

Now this specialized pincher dose give a chance to try different tappers.

But building one is probably just as involved as making the sleeve.

David

harder to make than a straight one.just have to mount the block in a lathe and cut the bore with the compound

Tried what you said and made a squeezer today .004 taper over 1/2" . Gave it a try and it works nice.

David very nice...on your next one...make it bigger so you can put an indicator on it so you can read on how much you squeeze it down at a time, not just by FEEL. JMHO

 

[Gator 340]

Well I was hoping that the Brass Head Button Topic would not come up till after the next couple of BIG Races!!!!! Steve is making them & I have never seen anything like them as for Performance they Provide. There is NO DOUBT that they Allow the Engine to Burn More of the Nitro Percentage that is Already in the Fuel by providing a higher heat to the prechamber. They are made out of what ever Steve Wood says they are made out of?? But the Alum ones will NEVER be back on my RS101s. & You better hope you got a pair or two for Hobart in a few weeks?? & Ralph already has some for Charleston........ Thats all I`am saying for now!! Done.....Now Back to the original reason for this thread!!!

**** Joe how fast you guys going...should be a Hundred by now with them 101 Peep Peeps...Brass heads,squeeze the water down,hell why use the water...

 

[dwilfong]

Just figured I would give a update on my testing.

I want to thank Scott Bouchie for the great pistons he made for me.

I have bin running the same Eng for 6 months now thew 4 races and testing with no problems.

The piston fit is perfect after all this running. must have more than 10 gal of 60% thew this Eng and bottom end has not bin apart.

Have gone thew a few button changes but no maintenance to the bottom end.

The 30% Si pistons did not work on the 1.01 thy where to brittle and would break the skirts. the new pistons where made from what Scott suggested from the start 12% Si.

The tapper at the top was done by my self with some sand paper in the lath and then lapped to fit.

This has worked very good. the fit was perfect after only a few tanks and has not changed after that.

The softer material seated real quick and once it found its own it has maintained that fit.

The material is more for giving and dose not break under high stress.

Again thank you Scott for the good advice and killer pistons.

David

 

[dwilfong]

I have run this new 12% SI piston now for 9 months have well over 20gal of fuel thew it.

In testing have taken plugs many times on lean runs trying to find the needle.

It seams this piston was losing some seal so I raised the CR to 10.5 and with a few runs finding the needle and taking some plugs the pinch got better. this material loves the heat! It seams to grow at the top with more heat and reseals its self. the sealing wear band on the piston is growing as the CR and heat build up.

I have never had a seal get better ever.

This just blows my mind would have never expected this result.

Just figured I would pass on my observations.

 

[Joe Warren]

David are you bringing Scotts piston size to the liner? How close are they?

 

[lohring]

This CMB piston grew a little too much. A round liner also helps.

Lohring Miller

 

[dwilfong]

David are you bringing Scotts piston size to the liner? How close are they?

Scott will fit it to the liner if you want.

The ones he made me stop at the top of the ex port. I fit them from there.

He fit one to the liner I sent for size but I lost that one with the bearing failure in the VAC 1.05.

Have two left from this last batch mad from the 12% Si

I am going to spend the cash on a diamond flex hone for the next fitting in this liner.

 

[dwilfong]

This CMB piston grew a little too much. A round liner also helps.

Lohring Miller

Lohring I think there where a few thing that added up to what you see.

As for me I am sold on this 4032 material from what I have seen so far.

Also 20% oil with Castor I think also helps.

 

[richard jones]

I had the privilege of spending a day with Mart Davis in the shop. he showed me a liner pincher that was made with a tapper cut into it.

He used it on one of my RS7 sleeve. he would turn the liner to preset marks on the jig using the centering pin notch as a reference. he used a torque wrench to tighten it at every mark.

He said this would give a .002 taper from the top of the ex to the top of the liner.

I still run this sleeve with new piston from CMB and it holds the pinch for a very long time.

The only reason I have changed pistons one time was the skirt broke at the bottom of the ex side.

For those of use that can't make are own liners we are stuck with what ever the factory gives us.

Now this specialized pincher dose give a chance to try different tappers.

But building one is probably just as involved as making the sleeve.

David

harder to make than a straight one.just have to mount the block in a lathe and cut the bore with the compound

Steve:

EXACTLY using steel for the lap and a 4 jaw chuck. I make a piece of aluminum that I turn using tyhe compound and moving until I get the correct taper. Then I bore the squeezer. with that setting.

I am not sure that my tapered squeezer is better than the one that Steve sells. I have used both and I am not sure I can tell the difference. For less than $50, I think that I will use Steve's for my other engines. After running the new Go Engines for a little bit, and using Steve's squeezer, I am happy with the results.

What a great thread..... People that are curious about the really technical side of the hobby can gain a LOT from this exchange!!

Interesting, I remember some years ago, when U and many others told me the liner squeezers that I made would not work and would ruin the liners, I originally made over 90 different liner squeezers for almost all of the boat engines and lots of car and truck engines, one of the 21 liners would take care of 14 different engines made by the same manufacturer, I am positive, I have squeezed over 10000 engines over these many years including car and truck engines and lots and lots of boat engines, in fact I still carry over 40 squeezers with me all the time. The biggest problem I have seen with most of the engines I have squeezed over these many years, is the liner fit was to tight in the case which would only let the liner expand very little into the case, especially during lean runs when the combustion chamber is super hot, which would result in the piston crown experiencing very quick wear and loosing a good seal. most of the engines I squeezed, the liner was so tight in the case, it took a lot of work and time to remove the liner from the case, and some were so tight I had to build a special fixture to remove them. JM2CW dick

 

[dr gary turner]

Dick, You squeezed my 67 CMB at least 4-5 yrs ago and has been the best motor I have had and am still running it. Crazy power!!!!!!!!!!!!!!!! Gary

 

[julianconde]

This CMB piston grew a little too much. A round liner also helps.

Lohring Miller

Ouch that hurts. I never had that problem with 101RS engines yet and I'm running 60% nitro 18 % oil and I add 3oz of Klotz kl100 per gallon and I mix 5 gallon batches at a time.

 

[eekern]

I had the privilege of spending a day with Mart Davis in the shop. he showed me a liner pincher that was made with a tapper cut into it.

He used it on one of my RS7 sleeve. he would turn the liner to preset marks on the jig using the centering pin notch as a reference. he used a torque wrench to tighten it at every mark.

He said this would give a .002 taper from the top of the ex to the top of the liner.

I still run this sleeve with new piston from CMB and it holds the pinch for a very long time.

The only reason I have changed pistons one time was the skirt broke at the bottom of the ex side.

For those of use that can't make are own liners we are stuck with what ever the factory gives us.

Now this specialized pincher dose give a chance to try different tappers.

But building one is probably just as involved as making the sleeve.

David

harder to make than a straight one.just have to mount the block in a lathe and cut the bore with the compound

Steve:

EXACTLY using steel for the lap and a 4 jaw chuck. I make a piece of aluminum that I turn using tyhe compound and moving until I get the correct taper. Then I bore the squeezer. with that setting.

I am not sure that my tapered squeezer is better than the one that Steve sells. I have used both and I am not sure I can tell the difference. For less than $50, I think that I will use Steve's for my other engines. After running the new Go Engines for a little bit, and using Steve's squeezer, I am happy with the results.

What a great thread..... People that are curious about the really technical side of the hobby can gain a LOT from this exchange!!

Interesting, I remember some years ago, when U and many others told me the liner squeezers that I made would not work and would ruin the liners, I originally made over 90 different liner squeezers for almost all of the boat engines and lots of car and truck engines, one of the 21 liners would take care of 14 different engines made by the same manufacturer, I am positive, I have squeezed over 10000 engines over these many years including car and truck engines and lots and lots of boat engines, in fact I still carry over 40 squeezers with me all the time. The biggest problem I have seen with most of the engines I have squeezed over these many years, is the liner fit was to tight in the case which would only let the liner expand very little into the case, especially during lean runs when the combustion chamber is super hot, which would result in the piston crown experiencing very quick wear and loosing a good seal. most of the engines I squeezed, the liner was so tight in the case, it took a lot of work and time to remove the liner from the case, and some were so tight I had to build a special fixture to remove them. JM2CW dick

I recently pulled apart a new picco .12 to blueprint for a .12 JAE I'm building. I had to heat the case in the oven to get the sleeve out....first time ever. I'm guessing this is way too tight. What is the proper way to fit the sleeve to the case?

 

[seaducerpete]

Wd40 and sandpaper should be a slip fit

 

[dwilfong]

Use WD40 and just spin the sleeve in the case till it slides in and out real nice.

You only want to relieve the top of the sleeve where the heat is.

This is the part that need to grow.

When you push the piston up in the sleeve See where it stops this is where the lose fit needs to be.

Do not do the whole length of the sleeve.