Deck Height

[Chris Craft crazy]

Tell me how to measure Deck height on a 430. I can think of a couple of ways to cheat it out, but if there's a right way, I want to know what it is.

[Theo]

Peter, a competent mashine shop will do exact measurements for you. Just ask them to give you the numbers. Make sure to talk to the guy who works on your block as sheets on a manager's desk might get confused.
If you don't have the right tools, your numbers might not b exact, no matter how well you do the math.

[Chris Craft crazy]

Well, the deck height is take from the center of the crank, to the top of the deck. So in this case, the center of the crank to the center of the cylinder at deck height is neither the height at the intake side, or the exhaust side.

Do you take the center deck reading and do the mathematical calculation based on the 10 degree deck angle based on the measured bore? That's my question. The other way to do it with the existing parts is to measure rod length, plus piston pin center to the top of the piston, in this case a flat piston top, them measure remaining distance between the top and bottom of the piston at TDC to the deck.

People keep talking about machine shops doing all kinds of things, but in the case of the rebuilt engine I just tore down, the pistons are wrong, the crank needs turning, the fuel pump rod is wrong, the push rods were not replaced, the exhaust manifolds were never disassembled and cleaned, and these folks are well know as a reputable vintage engine rebuilder.

The question on deck height came from an engine builder I know who have over 30 years of experience.

[Shelby#18]

People keep talking about machine shops doing all kinds of things, but in the case of the rebuilt engine I just tore down, the pistons are wrong, the crank needs turning, the fuel pump rod is wrong, the push rods were not replaced, the exhaust manifolds were never disassembled and cleaned, and these folks are well know as a reputable vintage engine rebuilder.

The question on deck height came from an engine builder I know who have over 30 years of experience.

So sorry to hear this. I'm on my second machine shop with the Mercury rebuild. And I'm beginning to wonder about the second one.

[Chris Craft crazy]

It happens, especially on vintage engines. Shops aren't familiar with the engine, parts are difficult to find, the amount of time necessary to find the right parts, and do the research can't be billed, so they don't bother, I bought the engine I am tearing down cheap, and didn't pay for the original rebuild anyway, but it's just an indication of what happens with very old relatively unusual engines. I have a engine builder who I trust to tell me when he hasn't experienced something before, and we find it out together.

[Theo]

Tell me how to measure Deck height on a 430. I can think of a couple of ways to cheat it out, but if there's a right way, I want to know what it is.

As you already have an engine builder you trust I won't get too deep into recommending my favourite engine builders. So to get back to your first question. Every method of taking measurements is the right one as long as it yields exact numbers.
Your machinist needs to install a "BHJ "2" inch Precision Bar" or something similar he might allready have.
I just sold my BHJ "2" inch Precision Bar"
http://www.bhjproducts.com/bhj_content/ ... xt/bar.php

They come with various adapter rings to make the bar fit a variety of engine block main diameters.
In the case of a MEL and if I had to do it instead of the machinist, I would use the bar and some sort of precision angle that had to be long on one side. There are also long rulers available that might help to do the job as well (maybe some modificatis needed).
Anyway here's my take on this.

1. Install a precision bar.

2. Place a precision ruler or angle on the precision bar and lean it closely against the intake side of the cylinder wall. Read the ruler or mark your, angle, straight edge or whatever you use where it meets the block deck.

3. Repeat this with your device leaned closely against the exhaust side of the cylinder wall. Take measurements as well.

I order to determine a piston's design and compression ratio a piston manufacturer needs to know an engine's block height. It is also very important to let him know about the 10° angle. Here's my math to determine a MEL's block height. The result is not a physical dimension, but a mathematical dimension that helps making calculations in the piston's design process.
My formula might not be all correct. Please suggest corrections if you think it's wrong.

MEL deck height = (1/2 X Precision bar diameter) + [1/2 X (reading exh. side + reading int. side)]

I made this scetch this afternoon and placed two devices that might give an idea of what I thought of

[Theo]

The above eyample is just a backyard method you could do. Off course there are professional tools that do the job a lot faster and more accurate.

[Chris Craft crazy]

That makes sense Theo, thanks... I will pass this on, and go from there...

[Theo]

You're welcome.

[Theo]

Peter, are you going to have the block deck milled? If that<'s gonna be the case, then take your neasurements after the milling process.
You will have to provide the piston manufacturer with the exact length of the connecting rod too. Make sure the connecting rods get a close inspection. In the very most cases they need to be done. They will end up being shorter.

Make sure to provide the piston manufacturer with the exact dimensions of the connecting rods, the deck height and the desired bore oversize AFTER the shop has done the required machining on the block and the con. rods.