Deck Height

What is deck height and how do you measure it?
Thanks.

That would be the height from the Top of the plank to the ground. A plumb bob and a tape measure will work, though a one of those ultrasonic distance gauges would be pretty good too.

In that vein it is the height above the water from the lowest deck, usually, but not always, the main deck. Is it the water in Kansas??

LAST EDITED ON Dec-18-03 AT 09:52 AM (CST)
 
ARRRRGGGGHHHHH! Matey!

"Fer that we be haulin' ya from the highest yard arm!!!!"

Somehow we missed "National Talk Like A Pirate Day" here at SSW.

Swashbuckels and Nitro Fumes!.......Hib

>Is it
>the water in Kansas??

There is no water in Kansas -- and few trees. I understand the FAA has advanced a proposal that all tree in Kansas be required to have read beacons installed on one of the top branches - navigation hazards.

Hi Paul:
I am surprised no one else has replied to you yet. The deck height is the distance from the top of the piston when the piston is at the top of its stroke (this is called TDC which stands for top dead center) to the head. Obviously I am talking about the part of the head that is the closest to the piston.
I use a depth micrometer to measure the deck height. You can use a dial caliper but it will be more difficult to get an accurate reading with the caliper. Regards, Bud Brautleht

LAST EDITED ON Dec-18-03 AT 06:25 AM (CST)
 
OH, sorry, wrong deck. Thought I was on the DIY site for a second.

Another method you can use, and we did on RC Combat engine mods all the time, was to remove the glow plug, stick a piece of thick solder with a bend in it so that it fits in the space between the lowest point of your head and the piston, if you have one of those trumpet heads, you have to get the solder to the side.

Rotate the piston over TDC a couple times, pull the solder out and measure the 'squish'.

Maybe not as accurate as possible, but it was close enough for the work we did. I'd think the average Stunt pilot would be a tad more anal about it, but if you were just wondering whereabouts the deck height on your motor is, thar it iz.

LAST EDITED ON Dec-18-03 AT 04:41 PM (CST)
 
>OH, sorry, wrong deck. Thought I was on the DIY site for a
>second.
>
>Another method you can use, and we did on RC Combat engine
>mods all the time, was to remove the glow plug, stick a
>piece of thick solder with a bend in it so that it fits in
>the space between the lowest point of your head and the
>piston, if you have one of those trumpet heads, you have to
>get the solder to the side.
>
>Rotate the piston over TDC a couple times, pull the solder
>out and measure the 'squish'.
>
>Maybe not as accurate as possible, but it was close enough
>for the work we did. I'd think the average Stunt pilot
>would be a tad more anal about it, but if you were just
>wondering whereabouts the deck height on your motor is, thar
>it iz.
>
>From somewhere near Parkville, Mo.
>William Crane
>AMA 6733

There need be no apologies made for this method of determining head clearance. True, on a one-time basis, it might not be the most accurate way to measure clearance, assuming one has all the correct tools.

However, it is repeatable with a very small margin of error from reading to reading. That alone makes this technique very effective.

On a related subject and thread, somebody asked how to be sure the piston is located at TDC when taking measurements. Don't care with the technique favored by Mr. Crane and myself.

I would also like to add that I prefer rosin-core solder, as it is basically an easily-squished tube which is both cheap and readily available.

Both of us are assuming--always a dangerous thing to do--that none of you will try measuring what is known to be less than .025 clearance with some big wad of solder that has a diameter of .150 or so. Definitely bad form.

For those in a hurry, don't use your electric starter. Please.

And always be aware that should you make the lower leg of the "L" too long and stick it into a bypass port before turning the engine over, you will be facing disassembly soon.

On our engines, for uniformity sake, it is usually measured, with the head removed, from the top of the piston at top dead center to the top of the rim. There are a couple of engines made where this will actually come out to zero. The head is made to sit on top and has the chamber hollowed out.

On the FP engines the deck height should be .190 measured this way and the head will fit down into the cylinder. The head depth also is .190, so that it will fit flush with the piston with no head gasket at all. Fortunately most of these engines have some additional deck height due to tolerances because several people have advocated running these engines with no head shims. BAD idea!

Since each design is its own (unless it is a clone of another) the measurements will vary, but it will affect both the timing of the engine (measured from the piston to the top of the cylinder) and also the compresson of the engine. There is usually a lot of variance in this measurement in mass produced engines as they come from the factory, and one of the first things you should check if you plan to make any changes.

G'day Paul,

To clear it up for you.........

Deck height is the distannce measured from the top of the liner, or in car engines the block deck, to the top of the piston crown.

Squish clearance is the distance between the piston crown to the underside of the squish band on the head.

Thanks all for replying.
Paul Allen