Ive seen a thread on here how to find out what it is,but cant find itI need to work out my comp ratio as i think its to high,problems with det and blowing head gaskets NOT due to fuel or timing.How can i work it out with the head off without any technical machines etc if possible? ive been told about deck hight at tdc to measure how far out the block the piston protrudes but what to do from there i havnt a clue can anyone shed any light on the subject for me please?

 

Just done a fast ford article on it if you can wait until next issue mate.

 

could realy do with it now tbh the engines in bits at the mo and need it back on the road but i will have to hold on if its a bit difficult to explain cheers stu.Can it be worked out without all these syringe gizmos and stuff??

 

you need to know your swept volume which is the volume of the cylinder made by the bore and stroke of your engine.

You also need to know your chamber volume, which is any volume above the piston, including the top of the bore, chamber in the head and headgasket space.

These are what people normally measure with a syringe, by putting a greased perspex plate over the chamber of the head or block and letting in paraffin with a calibrated burette.

after that you need to add the two together to get the volume with the piston fully down, and divide that by the smaller volume (piston fully up)

 

As a few of my friends would tell you im brain dead so what you have just wrote you may as well wrote in french or some other language lol.When it comes to maths im useless im the type of person that needs to see it done to understand whats bein said if you understand that lol.

 

go and get the two volumes and Ill sort it for you

 

When you say its measured with a calibrated burette what the feck is one of them??? Whats it measured in fluid measures i.e ml?

 

yeah, it measures volume

 

Thats whet i said in my first post i aint got any of these fancy gadgets and i dont know anyone that has need to find an easier way of doin it

 

no, you could try guessing if you like? Ill start at 11:1

 

get a syringe from the docrot that is one of them big plastic things for giving little kiddies medicine
they will be around the 10ml size although some can be as big as 25ml
turn your head upside down so it's flat (work it out with a spirit level on both planes)
put a bit of perspex over the top of one of the chambers and make sure there is a little hole in the perspex for you to drop bits of water or whatever you are going to use to measure out the volume of the thing
repeat this across the whle head to make sure that the head has a uniform and exact volume for each
then work out the volume of the cylinder when the piston is at the bottom of the stroke, bottom dead centre
now put the cylinder to top dead centre and measure it again
the first measurement plus the chamber volume of the head will be the total volume of the cylinder
the second one, with the piston at tdc will be the sweapt volume of the cylinder
and by comparing these 2 different vaules you will find the compression ratio
don't forget to add the thicnkness of the head gasket intot he equation
you need to find out it's total torqued down thickness rather than it's uncompressed thickness as this could be double what it's vaule is

and that's about it

unles you want to read stu's article which will tell you loads about others stuff as well as correcting the mistakes i may have made in this post

 

think i will wait and have a good read of stus article so it sinks into my brain coz im thick lol.