head check

[Guest]

Dave,

If that is what you been doing and it works for you by all means, keep doing it. Like the saying goes, If it aint broke don't fix it. I can certainly relate to the toys just seeting in the tool box to look pretty. Only time I use them is in the winter, when I rebuild the motors for the next season.

Gene,

.020 solder is what I also use also, keep some handy in the tool box, if I need it in a pinch. There is more than one way to skin a cat! In boating I learned a long time ago what works for one guy does not necessarily means it will work for another, just keep an open mind and use what you can use.

Bill Heacock

 

[boaterbill]

Gotta stop looking thru the post without logging in, seems like there is always something that is interesting to reply, then after I have to go log in. Horse before the cart!

Later.

Bill Heacock

 

[Tim Kish]

I personally prefer using the dial indicator method myself

and I have also made a depth gauge that uses the same indicator to measure the

dish in the piston.

The main reason I prefer this method is because I like to look at the head button

so I can see what is going on in the engine. You can learn alot about how your engine is performing buy the head button.

To me for the time it takes to remove the head it is well worth it.

Tim

 

[GTR]

Hi Guys

I agree that it's horses for courses - I use the solder (fine pc board type) regularly. Works for me.

There was another method nobody mentioned - take the head of, using a depth gauge (or end of verniers) measure from top of liner to piston. Measure from top of squish band to seating face on head - subtract the 2 measurements and you have head clearance. Piston rock mentioned is not really an issue in small nitro engines.

I don't think any method is totally accurate because of operator error but as long as you do it the same way each time you will always get similar results. Provided you use this knowledge and keep an eye on piston/squish condition you will get th results. Just chasing a magical head clearance is not the answer - some engines, same brand and all respond differently to head clearance because of the other variables - height above sea level, fuel % and type of oil, temperature, water temp and density. The variables are all there for everyone.

Have fun.

GT

 

[Don Ferrette]

"In gas engines I've found the solder method indicates about .004" more clearance than using a dial gauge. I believe it's because the piston tilts in the bore when solder is inserted on one side. Given that the piston has about .004" of clearance in the bore, that seems to be about what one would expect."

I can see getting .004" or more with a gas engine because of piston rock since there is far more cyl. wall clearance due to it being a ringed motor & the ring will compress allowing lateral movement. The nitro engines on the other hand, have a much smaller bore & tighter fit since they rely on cylinder to liner fit for it's seal. I went back thru some of my engine notes & found a page where I compared dial indicator vs. the Keeley gauges on some Picco's I used to run. The readings were all within .002" or less which in my notes I attributed to rod clearance, newer the rod the closer the difference. The solder method should work just fine based on two things, use soft solder & take your measurements in line with the wrist pin. Personally, I like the solder or gauge method as it takes into account rod/wrist pin clearance which, since the motor is constantly running under compression/explosion forces, would be preferred as these combustion forces are constantly pushing down on the piston trying to compress these clearances. Just my 2 1/2 cents ...........

 

[Terry Keeley]

We're getting ready to make another batch and will try to have them go down to 0.006" or so.  After you find what your head clearance is you can remove shims (which are normally 0.1 & 0.2mm or 0.004 & 0.008") to get down below 10 thou...

Terry-

Tried to send you a P/M but it bounces back as not good e-mail address.

Don my new e-mail address is [email protected], I'll try to change it in my profile...

 

[mark voorhies]

Terry,

Call me crazy, but I would sure like to see your head gauges

go down to .004. I'd buy a set.

 

[Terry Keeley]

Terry,Call me crazy, but I would sure like to see your head gauges

go down to .004. I'd buy a set.

Thanks Mark, our next run will be with gauges between 0.006" and 0.016" a more practicle range. Careful running down to 0.004", gets real easy to start "kissing" the head down there.

 

[Don Ferrette]

Terry-

You got an ETA on the next batch?? :blink: :blink:

 

[Terry Keeley]

Terry-You got an ETA on the next batch?? :blink: :blink:

Oh, sometime this year.

 

[Terry Keeley]

Probably sometime this spring...