Measuring squish band and deck height

Yeah I've been reading your procedure Don and plan to do the same. My questions were more related to the use of gaskets and assemblage of the pistons for measuring purposes only. I just don't have a spare base gasket (I did manage to salvage the head gasket). So I seemed to recall seeing someone say they measure deck height without the base gasket. I was hoping someone had a process for that. I do have an unused 550 gasket that I could probably use but it's slightly thinner than the oem 650 base gasket. I might go that route if measuring without the gasket is not possible.

Clay it is fine to use a new base gasket and head gasket when doing trial fittings even if they are torqued to specs. As long as they have not done any heat cycles then they will be fine to reuse. When you release the torque on the head gasket it will expand back to close to it's original thickness when new. Put the base gasket on dry for these fittings and give it a thin coat of grease on both sides when fitting it for the final time.

Yeah I've been reading your procedure Don and plan to do the same. My questions were more related to the use of gaskets and assemblage of the pistons for measuring purposes only. I just don't have a spare base gasket (I did manage to salvage the head gasket). So I seemed to recall seeing someone say they measure deck height without the base gasket. I was hoping someone had a process for that. I do have an unused 550 gasket that I could probably use but it's slightly thinner than the oem 650 base gasket. I might go that route if measuring without the gasket is not possible.

There are different ways of checking the squish band distance. The way I did it is covered in my build thread. You can also adjust the squish band distance by using different thickness base gaskets which is what I did.

On my motor the upper piston land was .022" above the metal liner in the cylinders. The head gasket was .050". The maths is 50 - 22 = 28. So the squish band clearance in my case was .028". To get it up to around .040" I needed the raise the cylinder head away from the pistons to provide more clearance. A thicker base gasket was my solution. There is a thread on how I made that base gasket if interested.



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[GregT]

Don't over think it. Put in stock gaskets and run it.

Well, yes, you could...but you've gone this far now...

You should be able to put a fresh base gasket in, do a trial assembly of the block and pistons - pistons without rings,pins just pushed in etc. Measure piston crown to deck distance - but don't forget to put spacers on at least 6 studs and nip the barrel down when you measure.
Piston crown edge to top of deck plus gasket thickness equals squish height.
Ideally you're aiming for around .040in or 1.0mm for road and general use.
Anything which needs to come off to achieve this comes off the top of the cylinder block.
If you're careful, the base gasket will be OK to use on the final build.

[boontonmike]

Don't over think it. Put in stock gaskets and run it.

Hey guys,

I've finally got the lower end of my 550/650 build together and now comes the fun part. I have a few questions for the experts. Sorry for so many as this is my first time going to this level.

I want to get the squish band right so I was wondering if I can put the cylinder on without the gasket or is it necessary to waste one for measuring?

If I can go gasketless, how do I determine the torqued thickness of the gasket?

If I put solder on the piston and measure the compressed thickness at the ends, that is telling me the squish measurement correct? How does that relate to deck height?

Lastly, do I need to measure each piston or can I get away with just putting one piston on and just measuring the one?

BTW, I'm using an OEM base gasket that measures .54mm thick and the head gasket measures 1.4mm.

Thanks,

Sci85