we'll be building the 2056 soon. this is what i'm working with.
a set of .039 2.0 heads (i'll have cc's soon)
96mm pistons (does any one have formula for volume X's space to deck height)
71 mm stroke

i've never done this and the links i've gotten make no sense to me. is there a basic formula for the above engine. how do i get the vlume (cc's?) of cylinder and how is that related to head cc's then how do i figure shims to get 9 or 9.5 compression? i'd think someone out there can suggest a close piston to deck height (say .045) if the head cc is the same(ish) to start with.

mike

check your PMs ...


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that's how i have done it in the past. bolt down cylinders using the studs and a flat piece.

do that *without* any shims.
measure the lip height (in mm) from the piston top to the cylinder edge.
that will give you the volume that you need to add to the cc of the head.

use the following to get the volume:

Volume = Pi • r² • height
Volume = 3.14159265 • (96/2)² • lip height
Volume = 7238.23 • lip height

so, for example, if the lip height is 4mm, the top volume that needs to be added to the head cc would be:

Volume = 7238.23 • 4 = 28952.92 = 28.95 cc

(note that you have to divide the inital result by 1000 to convert from cubic milimeters to cubic centimeters)

that means, if the lip height is 4mm, you'll have to add 28.95 cc to each of the head cc.
then use the cylinder cc volume (71mm stroke, 96mm diameter) to determine the compression ratio.

using the same formula to get the cylinder volume:

Cylinder Volume = 7238.23 • 71 = 513914.33 = 513.91 cc


compression ratio = cylinder volume / (headvolume + top volume)


that's your compression ratio without shims. you then add shims to increase the top volume until you get the desired compression ratio.


easy, eh?
Andy

Mike

use this calculator it will help you figure out what deck height you will want

you need the head cc's to proceed though

they will be around 52cc and your deck height will need to be around .040" to be close to where you want.

you will not know what size or if you will need any shims to reach this number

you may need to take your cylinders to get trimmed

i know you want to do this build in 1 day, but you may find it is going to take more time

heck,valve train geometry is going to take a while all by itself

What about the top of the pistons flat, convex, concave?

flat ...

i'm calling jake mon. about the head cc info.

i dont mean to give the impression i want to rush the build, i'm just trying to put all my ducks in a row out of respect for the guys that are coming along way to help out kenny. it's frustrating to me becouse i was a master mechanic for years before my motorcycle accident leaving my mind willing but body not.

about the valve train geometry... the stock set up should by fine tempararily with jakes 9050 cam, right? i would like to go to swivel feet eventually when we have the time and $.

thanks for the input, mike

mike go over to jakes site and read his valve train write up

his answer is no the stock set up is not ok. ( of course 1- 1,000,000 chance that the stock pushrods are the exact length you need on both your intake and exhaust side)