Deck height
Ok, here's what you need to know to figure out your compression:
Volume of combustion chamber in head.
Measure compressed thickness and diameter of "fire ring" on head gasket.
Volume above the piston to the top of the block when the piston is at TDC. If you have a flat top piston, you can just measure how far down the piston is from the head deck of the block, and then get the bore diameter. You can just use the stock stroke if you don't want to measure it, but measuring it will be fine.
Then I can walk you through the calculation or do it for you.
Also as far as measuring the volume of the cylinder at TDC while the engine is in the block, you can make a cover plate as I described in the link to my thread on how to check compression. Just put the fill hole to where it will be at the top of the block - even if it is not flat. A little "slant" is good also as it makes it easier to tell when the cylinder is full.
1- Volume of combustion chamber in head.........No problem, I will get this or work on this over the weekend.
2- Measure compressed thickness and diameter of "fire ring" on head gasket...........how do I get the compressed thickness if its not compressed? Do I have to torque down a new head gasket and run one just to get these measurements. Looks like these numbers are already know ( see post above ) but is that too inaccurate?
3-Volume above the piston to the top of the block when the piston is at TDC.........I can get this no problem assuming you mean measure the deck height or the height from the deck down to the top of the piston when the piston is at TDC, I do have a flat top piston.
If you mean the liquid than of course that is going to take a bit more.
4- then get the bore diameter...........I have this already as 3.95, I thought bore diam for slant was 3.40, why is mine a bit smaller?
5- You can just use the stock stroke if you don't want to measure it, but measuring it will be fine..........From what I have read I should not just use the stock stroke because of factory variances, I want to do everything I do correctly and most accurately. ( within reason, its not a high dollar racing engine that is going to see anything near 5 or 6 thousand RPM at any time ) I do not want to leave anything to chance, ( assuming that what I am leaving to chance will greatly affect the outcome I am trying to achieve) at the same time I want to know and understand why I am doing the things I am doing and that is why all the questions.
6- I am going to guess the reason you suggest using the liquid method is because ( in laymans terms ) I am measuring piston bore but that doesent account for cylinder wear below the top ridge in the cylinder. Is that correct?
How much would that wear change the end calculation, in other words if I were to just use the piston bore/compressed fire ring value and chamber CC # and not take into account the cylinder wear would it/could it throw off the end number a great deal?
Also as I mentioned above I guess I am going to have to decide what I am going to do with my head before I can CC it. Bigger valves are going to change that number I would think greatly.
