pistons tap heads..

[stangster50]

ok, i figured i would start a new thread, since its a different topic... if i just rest my gt40x-303 heads on my block, and spin the crank, i can hear each piston tap the head.. with no headgasket..

is that normal, to be that close.. or will a headgasket stop that? i really dont want to hurt my new heads..

 

[PUNISHER RACING]

a typical h/g is only .040 thick so ?

 

[Rick 91GT]

Wouldn't be totally out of the ordinary, that basically means you have .040 quench if you use a .040" head gasket. I am assuming the piston are 0 deck or slightly above the deck of the block?

 

[Mustang5L5]

Clay the heads and see how close you really are. Use a HG as well

 

[347HO]

Clay the heads and see how close you really are. Use a HG as well

To find your piston to deck height, just mic from the tops of your pistons @ their centerline with the pin to your block using a straight edge block. Whatever "in" the hole you are, add that to your quench. Whatever "out" of the hole you are, subtract that from your quench. As posted previously by many... your quench is with the gasket you're using in it's compressed state.

 

[stangster50]

To find your piston to deck height, just mic from the tops of your pistons @ their centerline with the pin to your block using a straight edge block. Whatever "in" the hole you are, add that to your quench. Whatever "out" of the hole you are, subtract that from your quench. As posted previously by many... your quench is with the gasket you're using in it's compressed state.

whats too close?

 

[Fast63]

I would say with the gasket you shouldn't run any tighter than .035, but I think you can run as close as .030 Use the straight edge method described by 347HO

Also, it can be normal for the piston to come out of the hole, it just should not come out a lot. Mine stick out .003 inches at top dead center. My head gasket is .044 compressed, so I'm getting a .041 quench.

 

[stangster50]

I would say with the gasket you shouldn't run any tighter than .035, but I think you can run as close as .030 Use the straight edge method described by 347HO

Also, it can be normal for the piston to come out of the hole, it just should not come out a lot. Mine stick out .003 inches at top dead center. My head gasket is .044 compressed, so I'm getting a .041 quench.

ok. ill have to measure.. i have the felpro 1101-1's? that sound right? i unno... but crushed, is .041 i believe.

thank you.

 

[347HO]

ok. ill have to measure.. i have the felpro 1101-1's? that sound right? i unno... but crushed, is .041 i believe.

thank you.

I have "zero" deck and I do use fel-pro 1101-1 gaskets.

 

[stangster50]

To find your piston to deck height, just mic from the tops of your pistons @ their centerline with the pin to your block using a straight edge block. Whatever "in" the hole you are, add that to your quench. Whatever "out" of the hole you are, subtract that from your quench. As posted previously by many... your quench is with the gasket you're using in it's compressed state.

sorry.. not sure i understand this too well.. can you better explain how i can get exact measurements? i put a straight edge across the deck/piston, and the piston does come out of the bore a bit.

also... my felpro 1011-1 gaskets say they are .041 thick... is that compressed thickness?

 

[88stangmangt]

.100/.80 is the min on valve clearance.....

You also didnt mention what kinda pistons,cam?? all important factors...

 

[347HO]

sorry.. not sure i understand this too well.. can you better explain how i can get exact measurements? i put a straight edge across the deck/piston, and the piston does come out of the bore a bit.

also... my felpro 1011-1 gaskets say they are .041 thick... is that compressed thickness?

Since your piston is out of the hole, measure from top of piston to the block from the pistons centerline with the pin using a depth mic.
You can also measure your piston rock by measuring the inboard or outboard piston edge while pushing down firmly with your finger the opposite side your measuring, then push firmly the same side your measuring, add them, then divide by 2.
It works and it will tell if anything is screwy going on.

If your block has not been "square" decked, then it's possible your measurements will vary by .002" to .010" from cylinder to cylinder.

It's interesting you've opted to build and engine with the pistons out of the hole... experienced engine builders find themselves dealing with many clearances which can get first timers and novices into trouble without even knowing.