MAC 45 Head clearance

[Heartbeat]

I am using a head clearance dial, like the ones sold at Speedmaster.

When checking the head clearance I noticed the MAC piston has a concave shape

So what numbers do I want to see. Accorind to CMD Website .008 is right But that can't be right using this tool.

Thanks Mike

 

[David Homer]

Mike, what you'll need to do is to pull out the piston and measure the depth of the dish. I have a CMB 3.5 greenhead, and the dish in my piston measures .020. Knowing that, you can then measure your deck clearance like you would normally, just set 0 at .020 on your gauge...

 

[Heartbeat]

Thanks David

Does anybody know the Dish Depth in a 45 MAC? Are they all the same?

Mike

 

[Don Ferrette]

Just get a set of (Terry)Keeley head guages which go in thru the plug hole & measure out at the squish band. B)

 

[Jerry Wyss]

Does anybody use "Plasti-gage" on this site? :huh:

Gawd! I'm Shocked

 

[Heartbeat]

Thanks Guys

I pulled the piston and did it that way for now.

Thats not my problem

Mike

 

[P THOMAS]

The piston dish should be .036 deep

zero the speedmaster tool using the head button flat on the table.

then you can assemble the head to the cylinder,, tigheten two screws

now screw in the tool and measure

be sure to read the dial the correct way around from zero

with the 004 shim you may get .046 subtract the .036 dish depth = head clearance .010.

the motor comes with a .008 shim only thing you need do after it is broken in is replace the .008 with the .004 shim

Power surge sells a mac 45 shim kit of different size shims to get what you want.

 

[Heartbeat]

Thanks Phil

My Piston Dish is .017 deep, motor reassembled I get .027 so I am getting a head clearance of .010

Mike

 

[P THOMAS]

Thanks Phil
My Piston Dish is .017 deep, motor reassembled I get .027 so I am getting a head clearance of .010

Mike

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OK guess you are good there,, those pistons must have some variance best to check for sure..

PHIL

 

[Dan_Cousin]

On my CMB I take the piston out and put the head in the piston and zero the depth gauge there. This takes the dish into account. Then the reading is directly the clearence.

 

[Don Ferrette]

On my CMB I take the piston out and put the head in the piston and zero the depth gauge there.  This takes the dish into account.  Then the reading is directly the clearence.

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Boy you guys sure create alot of extra work for yourselves.

 

[mark voorhies]

On my CMB I take the piston out and put the head in the piston and zero the depth gauge there.  This takes the dish into account.  Then the reading is directly the clearence.

105227[/snapback]

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Boy you guys sure create alot of extra work for yourselves.

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GEEZ,

Measure your head clearance at the outside of the head inside liner!

Use keely gauge, solder, or make your own from feeler gauges.

It's just got to be the outside measure where head fits into liner!

 

[Jerry Wyss]

I'll just sit here and shake my head :lol: :lol: solder :lol:

 

[Jerry Wyss]

Ok Guy's, I just couldn't let this "slide by"

Go to a NAPA auto parts store or most any auto parts store and ask if they have, OR can get you some "PLASTIGAGE". It's usually used for finding the clearance in all sort's of Auto Engine and Drivetrain clearances. It's works great in getting the headspace in your model engines FAST! In 1/100th the time of other methods. All it is , is a exact dia soft plastic that is flattened between the piston and squishband,

you can cut off a 1inch plus piece and bend it in a "L" shape, stick it thru the plug hole, turn the piston up until it's completely flattened the Plastigage, gently pull it out and measure the thickness with a caliper. Don't have a caliper? There's a "scale" on the side of the package that will tell you what your clearance is by how "wide" the gage has flattened.

Plasigage comes in different colored packages, GREEN for .001 to .003,, RED for .002 to .006, BLUE for .004 to .009 and there's a YELLOW for . 009 to .014..

It dosen't cost very much and it's accurate enough for the "main and rod bearing"

clearances on a Full Blown V8 Race engine!

Now, Someone always Pop's-Up and say's, "Yeah But What About The Piston and Rod Slop Allowing The Piston Going Farther Than the Gage Say's",, Well Just Subtract .001 from that measurement if that bothers you so much,,Or .002 if your running a Really Big motor ,,or "rattle can"

It's "Painful" for me to hear all these other methods,, They will drive You Insane :blink: