I had to get my shovel out to dig this old thread up as it's been so long
Any way, heres a mini up date, first off a recap...
I bought that pina bottom end and found out the pistons hit the head
The bloke who i got it from has still got the matching head which is knackered because it's cracked, he said if i cover the postage i could have it which would have been brilliant because i could copy the combustion chambers from it to mine but for what ever reason i've been waiting for WEEKS for him to post it to me and it's still not here
So i'm working a little blind and starting work on it now with out the pina head to copy from, the main thing is i don't know the proper squish height and wheather the squish height is even accross the whole of the squish area i'm working on ?
After a good dig around on the net i'm going with a squish height of between 0.9mm and 1.0mm, i think 1.0mm is 0.040" in imperial ? Do you know if this sounds about right ?
All i've done so far is to repeatedly(sp?) dummy fit my head with an old head gasket and smear some engineers blue marker stuf on the pistons so it marks the head where it needs grinding down when i turn the engine by hand.
Where i'm up to at the mo is that i've got two chambers ground out enough so that they just have enough clearance to go past TDC. With these two chambers done fairly care fully i have ground the bulk of the shape out of the other four chambers, next stage is to repeat the dummy fit/engineers blue/grinding process that i did with the first two chambers.
After that comes the tricky bit of grinding the squish clearance out. What would be handy to know is how thick the head gasket is when it's compressed so i could substitute the H/G for some thing the right thickness so i could carry on with the dummy fit/engineers blue/grinding process as it will be easier and a more accurate way of getting a consistant gap/shape.
Some one has sugested i could carry on with the dummy fit/engineers blue/grinding process with out a H/G but i'm guessing this will make the squish clearance too big.
Too big is almost as bad as to small because it can make an engine more prone to knocking so i've read, so people using a thicker H/G to lower the C/R might not be gaining much by chosing that way to lower the C/R ?
Any way, sorry for the long post heres a couple of pictures,
Part way through showing the engineers blue marking
You can't see it very well from this picture but the new surface is about 22 degrees
To measure the clearance i've bought some plastigauge as sugested by Gareth
Email FTW
