The Cal-look Lounge

Cal-look/High Performance => Technical stuff => Topic started by: baz on October 03, 2016, 17:45:09 pm



Title: Measuring cylinder lengths
Post by: baz on October 03, 2016, 17:45:09 pm
Hi I'm in need of advice again folks.  I'm trying to measure deck height with some new long cylinders so I can work out how much I need them shortened.

Should I just use one cylinder for position 1+2 then use this figure  and request my machinist cut 2 cylinders to this exact length.

Then use a different cylinder for position 3+4 and request 2 cylinders cut to this exact length?

Hoping someone can set me straight on this so I can get my cylinders sent off for cutting.

Thanks barry


Title: Re: Measuring cylinder lengths
Post by: baz on October 04, 2016, 15:54:56 pm
Well the silence is deafening on this one!  Usually a sign of a silly question  ;D

The figures I'm worried over are so miniscule that they aren't worth worrying about.

I'm ok about looking silly while looking for answers, much better imo than looking silly after fucking things up ;)

Cylinders getting boxed tonight and heading away for cutting to one supplied length.


Title: Re: Measuring cylinder lengths
Post by: Tufty65 on October 04, 2016, 22:07:56 pm
Well the silence is deafening on this one!  Usually a sign of a silly question  ;D

The figures I'm worried over are so miniscule that they aren't worth worrying about.

I'm ok about looking silly while looking for answers, much better imo than looking silly after fucking things up ;)

Cylinders getting boxed tonight and heading away for cutting to one supplied length.

I don't really know if my answer will be correct but wouldn't you cut them all the same length otherwise one side will have a different deck height and compression than the other side, only by a small amount obviously unless there was something amiss of course.

But you probably knew that anyway.


Title: Re: Measuring cylinder lengths
Post by: Erlend / bug66 on October 04, 2016, 22:53:39 pm
You need to check all the cylinders..

The crank coul be in the middle, off too one side, or crooked (1 and 4 longer out (or 2/3))

The important thing is that both sides are straight with cylinders mounted.


Title: Re: Measuring cylinder lengths
Post by: baz on October 04, 2016, 22:58:43 pm
Well the silence is deafening on this one!  Usually a sign of a silly question  ;D

The figures I'm worried over are so miniscule that they aren't worth worrying about.

I'm ok about looking silly while looking for answers, much better imo than looking silly after fucking things up ;)

Cylinders getting boxed tonight and heading away for cutting to one supplied length.

I don't really know if my answer will be correct but wouldn't you cut them all the same length otherwise one side will have a different deck height and compression than the other side, only by a small amount obviously unless there was something amiss of course.

But you probably knew that anyway.

Hi tufty

I just realised my first post doesn't contain all the info needed for anyone to give an answer!  I posted in my build thread the other day about where my problem is.

I have .11mm more deck on 1+2 than on 3+4.  That is from the crank centre line being slightly off centre I guess.

This is the reason I wanted 2 cylinders cut to suit 1+2 and 2 cylinders cut .11mm longer for 3+4 so both sides end up with equal deck heights.

There's a puffteenth between 1+2 and 3+4 also but close enough to not be concerned with. I mocked each rod/piston/location to get matching pairs as close as possible.

I have had a few emails and private messages from a couple of guys here who have helped me decide what to do, thanks guys for the help  

So I'm getting 2 cut to suit 1+2 and 2 cut to suit 3+4 to make both sides equal.

Hope that makes sense, I'm confusing myself just typing it  :D


Title: Re: Measuring cylinder lengths
Post by: baz on October 04, 2016, 23:08:12 pm
You need to check all the cylinders..

The crank coul be in the middle, off too one side, or crooked (1 and 4 longer out (or 2/3))

The important thing is that both sides are straight with cylinders mounted.

I had asked stateside about decking my case to crank centre line ages ago and he said was not needed. I guess it would cure my offset issues though.

But then I could run into matching piston heights due to rod and piston pin height variances?  I know I was able to get matched pairs for each side by moving rods and pistons around to find ideal locations. I ended up taking out quite a lot of difference this way.



Title: Re: Measuring cylinder lengths
Post by: Tufty65 on October 04, 2016, 23:09:20 pm
Well the silence is deafening on this one!  Usually a sign of a silly question  ;D

The figures I'm worried over are so miniscule that they aren't worth worrying about.

I'm ok about looking silly while looking for answers, much better imo than looking silly after fucking things up ;)

Cylinders getting boxed tonight and heading away for cutting to one supplied length.

I don't really know if my answer will be correct but wouldn't you cut them all the same length otherwise one side will have a different deck height and compression than the other side, only by a small amount obviously unless there was something amiss of course.

But you probably knew that anyway.

Hi tufty

I just realised my first post doesn't contain all the info needed for anyone to give an answer!  I posted in my build thread the other day about where my problem is.

I have .11mm more deck on 1+2 than on 3+4.  That is from the crank centre line being slightly off centre I guess.

This is the reason I wanted 2 cylinders cut to suit 1+2 and 2 cylinders cut .11mm longer for 3+4 so both sides end up with equal deck heights.

There's a puffteenth between 1+2 and 3+4 also close enough to not be concerned with. I mocked each rod/piston/location to get matching pairs as close as possible.

I have had a few emails and private messages from a couple of guys here who have helped me decide what to do, thanks guys for the help  

So I'm getting 2 cut to suit 1+2 and 2 cut to suit 3+4 to make both sides equal.

Hope that makes sense, I'm confusing myself just typing it  :D

Yeah I think that's what I meant to say, 1&2 the same and 3&4 the same so the deck matches in all 4


Title: Re: Measuring cylinder lengths
Post by: baz on October 04, 2016, 23:30:48 pm
Well the silence is deafening on this one!  Usually a sign of a silly question  ;D

The figures I'm worried over are so miniscule that they aren't worth worrying about.

I'm ok about looking silly while looking for answers, much better imo than looking silly after fucking things up ;)

Cylinders getting boxed tonight and heading away for cutting to one supplied length.

I don't really know if my answer will be correct but wouldn't you cut them all the same length otherwise one side will have a different deck height and compression than the other side, only by a small amount obviously unless there was something amiss of course.

But you probably knew that anyway.

Hi tufty

I just realised my first post doesn't contain all the info needed for anyone to give an answer!  I posted in my build thread the other day about where my problem is.

I have .11mm more deck on 1+2 than on 3+4.  That is from the crank centre line being slightly off centre I guess.

This is the reason I wanted 2 cylinders cut to suit 1+2 and 2 cylinders cut .11mm longer for 3+4 so both sides end up with equal deck heights.

There's a puffteenth between 1+2 and 3+4 also close enough to not be concerned with. I mocked each rod/piston/location to get matching pairs as close as possible.

I have had a few emails and private messages from a couple of guys here who have helped me decide what to do, thanks guys for the help  

So I'm getting 2 cut to suit 1+2 and 2 cut to suit 3+4 to make both sides equal.

Hope that makes sense, I'm confusing myself just typing it  :D

Yeah I think that's what I meant to say, 1&2 the same and 3&4 the same so the deck matches in all 4


That's the goal yes.