Cmb 21 Beta head clearance

[Mike lasorsa]

Running 40% nitro what should the clearance be? I believe it came with no shims

 

[Danny King]

.007-.010” hydro
.010”-.015” mono

 

[Mike lasorsa]

.007-.010” hydro
.010”-.015” mono

So basically leave it with no shim? Don’t really have the correct tools to check it

 

[Danny King]

No. Not at all. You need to know what the clearance is.

 

[Mike Hughes]

So basically leave it with no shim? Don’t really have the correct tools to check it

Find someone that does or invest. Worth the money IMO.
Mike

 

[Mike lasorsa]

No. Not at all. You need to know what the clearance is.

Ok didnt know that these things varied so much. Figured there would be .001 difference between motor to motor

 

[Mike lasorsa]

Find someone that does or invest. Worth the money IMO.
Mike

What is all needed tool wise? I have to many boats to not invest

 

[Mark Anderson]

An inexpensive pair of calipers is all you need. I run mine at .008 mono and hydro.

 

[Mike Hughes]

https://www.amazon.com/Digital-Cali...80832612&sprefix=calipers,aps,167&sr=8-3&th=1These will get you close.

https://www.amazon.com/Neiko-01407A...80832749&sprefix=calipers,aps,167&sr=8-5&th=1A little better quality being made of stainless steal.

Mike

 

[David Ashcroft]

Running 40% nitro what should the clearance be? I believe it came with no shims

Depend on bowl cc..
19cc is OK ..

 

[Bradley Maglinger]

OTHER-PRODUCTS

Scroll down to SPDG-100S Gauge Assy.

Many ways to check it, this is what I use. You can choose to buy the kit or get one of each adapter and buy a digital gauge at harbor freight.

 

[Terry Keeley]

https://www.amazon.com/Kester-Rosin-Core-Solder-Dispense-Pak/dp/B017WK9HQS

 

[Rod Fonda]

I get close with a vernier caliper,then use the solder trick down the plug hole to recheck,,make sure the solder is touching the cylinder wall,,biggest problem is with the piston pushing the liner up at TDC because of the nip,,Either shim up the liner a 1/4 inch and subtract or with the head on, turn the engine over till you feel its at TDC, then remove head and measure,,I think I've also heard of some guys using plastigage to measure

 

[Mike lasorsa]

Find someone that does or invest. Worth the money IMO.
Mike

So I did the solder trick and with no shims it’s .015

 

[Mike lasorsa]

No. Not at all. You need to know what the clearance is.

With no shims it’s .015

 

[Danny King]

With no shims it’s .015

That doesn’t sound right.
Is the engine brand new? Was it in a sealed box? Most engines come with shims. Not seen an engine come in with .015” with no shims.

 

[Mike lasorsa]

That doesn’t sound right.
Is the engine brand new? Was it in a sealed box? Most engines come with shims. Not seen an engine come in with .015” with no shims.

New engine I bought it with the boat I did take it fully apart and you can see if has never been run. It did include 2 shims they just were not installed. Shims are .001 and .002

 

[BrianNeumann]

Daniels Racing on IW occasionally builds & sells a dial indicator similar to the Speedmaster shown above. Has a sleeve on the base w/standard glow plug threads. And can make an adapter for turbo glow plug buttons. W/O any shims in place, 1st Install tool into plug hole & use it to locate piston ATDC. Remove button with tool attached, place button on a flat surface and set it to 0. Reinstall button on engine w/tool attached, zeroed & no shims gives you the true head clearance measurement. Remove button, add shims required to raise button to preferred head clearance & your done. This is the method I like best & compensates for any dished/domed piston as well.
Brian Neumann

 

[Mike lasorsa]

Daniels Racing on IW occasionally builds & sells a dial indicator similar to the Speedmaster shown above. Has a sleeve on the base w/standard glow plug threads. And can make an adapter for turbo glow plug buttons. W/O any shims in place, 1st Install tool into plug hole & use it to locate piston ATDC. Remove button with tool attached, place button on a flat surface and set it to 0. Reinstall button on engine w/tool attached, zeroed & no shims gives you the true head clearance measurement. Remove button, add shims required to raise button to preferred head clearance & your done. This is the method I like best & compensates for any dished/domed piston as well.
Brian Neumann

Ok I did the solder trick and im
Showing .015 with no shims which seems way off

 

[Mike lasorsa]

That doesn’t sound right.
Is the engine brand new? Was it in a sealed box? Most engines come with shims. Not seen an engine come in with .015” with no shims.

Maybe since it’s not broken in it’s showing more clearance?