Euro Hybrid Compression Ratio
07-25-2012, 10:24 AM
#16
Nordschleife Master
The problem with turning the crank around is that the lifters aren't pressurized and the cams snap back to a medium position. Putting the crank at TDC and turning the cam is better but still no oil pressure in the lifters which will make the valve extend a bit further.
I had bent valves (albiet minor) from over-revving the engine. It's that close. And what of decking the heads and block? Is it interference when taken down and still is spec.
Doesn't really matter though.
I had bent valves (albiet minor) from over-revving the engine. It's that close. And what of decking the heads and block? Is it interference when taken down and still is spec.
Doesn't really matter though.
07-25-2012, 11:07 AM
#18
Nordschleife Master
Easier approach: don't do that! I've replaced the rotor and it's set for 6450.
07-25-2012, 06:39 PM
#19
Rennlist Member
Wrong again MK........
Not all euros are interference. I have repaired an 84 euro (twin dizzy) that had a broken cam that had no valve touch. I also had an 85 euro that when doing the belt I rotated the engine at many cam positions and nothing touched. Documentation shows that somewhere in the 84 year the pistons changed to bump up the CR and after that they are supposed to be interference motors. But from 78-mid 84 euros were NON interference from the factory.
Not all euros are interference. I have repaired an 84 euro (twin dizzy) that had a broken cam that had no valve touch. I also had an 85 euro that when doing the belt I rotated the engine at many cam positions and nothing touched. Documentation shows that somewhere in the 84 year the pistons changed to bump up the CR and after that they are supposed to be interference motors. But from 78-mid 84 euros were NON interference from the factory.
rotating the cams or the crank is no assurance of anything. one piston has to be exactly at TDC, when you rotate the cams, OR, one cam lobe has to be FULLY depressing a valve when you spin the crank what was this the case in your situation? if so, and you did have your engine at TCD #1 and rotated the cams, did you think for ONE FRIGGEN MINUTE about the lifters not being pressurized when the engine is not running???? HMMMMMM??????
Back to school!!!!!!
so, if you still doubt it, understand the lift of the euro cams. under just under .5" of lift. valve reliefs are .175 for the 85s and near .3" for the 82s.
you figure out how they wont touch if engine is runnning and the belt breaks.
Now, say your sorry!
07-25-2012, 06:48 PM
#20
Rennlist Member
Plus, it would kill the compression ratio from 2cc to near 8cc like the lower compression pre '84 euro motors..
