Compression In My 4k

[trav_555]

ok guys i am using ae86dc's calculating Static Compression Ratios guide, but I'm not 100% sure how to calculate CH (chamber Volume)

 

now ive been told that my new engines head has slight head work to it, how do i work out Ch? it has flat top pistons so do i + or - or neither? with combustion chamber volume, how do i work that out, and how do i work out spark plug volume and how do i work out displaced volume of head gasket?

 

i want to work it out becuase i want to take the compression up higher, by machining the head.

 

Thanks in advance, need help asap!!

[Taz_Rx]

CC the head....with a spark plug in it!

 

The bore diametre, head gasket thickness, and some high school maths will get you the HG voluum. :)

[trav_555]

ok, what tools will i need to do a cc test, can i use a syringe to measure? and what are the thicknesses of normal gaskets?

 

will it run with 98 at 10.5:1 compression?

 

Cheers

[Taz_Rx]

A "head sized" sheet of perspex, a drill, grease and yes a syringe. Sound like you can work out the rest. :)

 

Get a gasket and measure it.

 

Yes 98 will be ok.

[trav_555]

sweet as thanks man, will the compressed gasket size be much different than the normal gasket size?

[philbey]

My engine builder suggested that 30-40 thou was about the right compression thickness for the head gasket on my 5K

[trav_555]

ok thanks, the mechanic said it was 40 thou un compressed but i need compressed. umm should i take it off block or head?

[Banjo]

Here's a link that may help you. It's pretty straight forward & written simply.

 

http://www.totallytriumph.net/spitfire/ski...your_head.shtml

 

Hope that helps !

Edited September 19, 2008 by Banjo

[trav_555]

Thanks ill check it out.

[archangel62]

Just a quick thought - you may be able to CC the head fairly accurately with it still on by using the syringe technique at TDC on #1, but with the cam at 180degrees (as in, both valves closed on number 1, at the top just "after" the spark would have occurred). If you take the spark plug out, you lose accuracy there, but it's likely to be +/-1cc or so, whereas if you try to do it with a valve open, you could be a mile out. Of course taking the head off is preferable but it's nice to get an idea before you jump in the deep end and rip the engine apart. If you look carefully at how far the plug appears to sit into the hole, it'll give you a rough idea where to fill the chamber to. Just be mindful of air bubbles, the car/engine may need to be at some stupid angle to get rid of them, and if you don't they'll throw your measurements way out. Have fun!

[trav_555]

ive got the head off, its getting the valves and seats machined as the "lip" was like 3mm when its supposed to be around 1mm

 

so i can't do it with head on as its not on :dance: