How to use plastigauge for measuring head clearance

[XtremeRcBoats]

I bought some plastigauge to measure the head clearance. Have not used this stuff before. What is the best way to use it, can you do the same as with a tin wire and stick it through the plug opening?

 

[FloridaScaleBoater]

Cannot use the same as with tin wire/solder.
Plastigauge is not bendable.
How I use, remove head and cooling jacket, cut a piece of plastigauge to fit side to side on piston top,
Reassemble head and cooling jacket, tighten to specs, rotate engine over by hand.
Remove head, measure the squashed area of gauge using the colored measuring squares on package.
Adjust with shims to desired clearance.

 

[Daniel's Racing]

You never want to rely on anything that takes compressive force to take measurement.

Especially when building engines in around .010" squish

 

[Dave Gilles]

You never want to rely on anything that takes compressive force to take measurement.

Especially when building engines in around .010" squish

i'd personally trust plastigauge being that it's for crank bearing clearances. Solder on the other hand I have never been able to get super accurate. Lots of tolerance stacking there.

 

[Daniel's Racing]

Problem is the compressive force required to compress the material also compresses the rotating assembly and stretches the top end assembly and skews the reading by some amount. You want a totally relaxed assembly with no forces being applied when measurement is being taken.

 

[Wasted wages]

Problem is the compressive force required to compress the material also compresses the rotating assembly and stretches the top end assembly and skews the reading by some amount. You want a totally relaxed assembly with no forces being applied when measurement is being taken.

We could argue these points all day long,,,
I’ve done them both ways… but Danny’s gauge is the only one that gives repeatable results every time. Worth every penny!

 

[Danny King]

Throw it in the trash and physically measure it.

 

[timothy johnson]

How hard can it be!

 

[Kris Flynn]

when an engine is running it is under compressive load?

 

[FloridaScaleBoater]

when an engine is running it is under compressive load?

That's kinda why I like the plastigauge.
You are actually getting a measurement that is showing any slop in rod, wrist pin & crank pin.
Just my thoughts, but what do I know??

 

[Buckshot]

I’ve never used plastigauge or solder. I’ve always wondered if the location of the compressive material would affect the accuracy of the measurement as it’s placed in different locations around the circumference of the cylinder. i.e. it would measure a tighter squish directly above/parallel to the piston pin and less squish 180*/perpendicular to the piston pin due to the piston rocking in the sleeve. This might not be the case as I’ve never tried it.