Ok so I have been reading a little on DECK HEIGHT and(piston to cylinder block deck area at TDC) & BLOCK HEIGHT (center of crank main journal to cylinder block deck). Now reading from article to article, I see people referring to Deck Height as if it wereblock height and vice versa.

Why wouldn't the Deck Height be measured as Block Height in the first place. Could this be because the Block height has a variable tolerance windowlike every other machined part?

Or could the Deck height just be a measurement for connecting rod& pistons assemblies for achieving the correct valve-to-piston clearance to not cause damage?

[sm=feedback.gif]

 

Deck Height, Block deck height, engine deck height ?

Over the life of an engine, the Block Height stays fairly consistent (wear of bearings) whereas the Deck Height changes by sheer ac***ulations of carbon on the piston.

Once cannot do much to modify the Block Height, but a little polishing and grinding of either the combustion chamber or heads or gasket thickness can easily change the Deck Height.

I think the variation of terms is unavoidable due to the word "deck" on all of them ...


Deck Height is the space between the piston dome and the combustion chamber, at top dead center (TDC).

Deck Height: The distance between the flat "quench" surface of the piston and the top of the bare cylinder (no head gasket).

Block deck height: is the distance between the centerline of crankshaft to the flat of the deck surface.

adding to the confusion of terms, in this, they call it "engine deck height"
http://www.faliconcranks.com/pdf/rod...ion_height.pdf



.

 

Just to add to information Stealth provided. Most concerns about deck height involve some kind of racing / custom application. In the building process the distance between centerline of crankshaft and deck (cylinder head mating surface) has to be considered as to stroke of crank, rod length and piston pin placement. Deck height can vary from bank to bank. 'Equal Decking' can be done to correct it. 'Zero decking' is intended to have the flat part of piston head even with block deck. Decking is more about compression except when using aluminum rods (they can scretch causing piston to hit head) Align boring/honing will have a very small effect on deck height. The SBC was the most common engine to be 'DECKED' not sure why but it was a common practice to change deck height from 9.030 to 9.000. In 'Rules' type racing after mock up( short block assembled with crank, rods,bearings,and pistons to be used) piston to deck clearance would be measured. Depending on measurement and what builder wanted. Block could be 'decked' sometimes for a second time. Normally those who are concerned with deck height or how far the piston below or on rare occasions above the deck are intending on some kind of competition application. A warning to those who are blueprinting in which may involve decking: Write down any and all numbers and letters stamped into surfaces that may be machined or they may be lost, this specifically applies the Chevy small and big blocks. I knew a guy restoring the 69 SS 396 he had since 71. Disassembled engine sent to machine shop only thing not requested by builder was decking when asked the owner said ok. original engine just another engine now It took 2 years to find out what the original stamping were and get block restamped.

 

ZERO decking means milling it to piston face level huh. Never knew that prior to now. My sister and I have to follow a "deck" height rule in the racing class we are in with 305s. So, I am somewhat familiar with that for racing. I hadmy 4-bolt 350 chevy block decked, but I never took the numbers/letters down for the block's stamped ID number.

What about Cadillac Block & Deck Heights?

 

Decking is generally reserved for competition. As a general rule (with steel / cast iron rods) there needs to be .040 between piston at TDC and cylinder head. With your 305 ideally you want the piston to deck clearance to be at the minimum spec. they allow and use a head gasket that's compressed thickness added to how far piston is below deck that will come close to the .040. Combustion cambers cc'ed and heads surfaced to reach min.cc rules allow so that you can reach max compression ratio. It all depends on your budget sometimes it's not about the cubic inches its more about the cubic dollars you can afford to spend. This is just a sample of what 'just getting competitive' can entail. There are a few sites on the web specializing in the 472/500 engines.

 

Yeah, do you or anyone else happen to know the Factory measurements of the EFI and carbureted engine blocks? I am sure one of my Factory manuals for the EFI engines might display that. I would have to look though. Since we are talking about Block heights &deck heights, we should post what Cadillac's engines have in this thread.

 

Which engine?

 

Well start with any carbureted engine model and work to todays engines I guess. Make this a FAQ worthy or "pinned" topicsince I haven't found anything searching on this type of topic. I will see if my books list anything.

And we should try and list ANY cylinder block problems from over the years if there were any for the engine block castings.Another idea could be listing OVERboring limits of these blocks also.

 

Alright, well I havent had any luck with finding block heights or deck heights yet.