piston valve contact help please
Turbo Mini Forums

i looked at my engine today, pistons 2+3 have had valve contact its very light and you cant feel any damage to the piston when running fingers over them

im shitting a brick now! this was with mg cam and 1.5 rockers, my new build has about 10 thou less on the piston to deck height and i am now running a ph2 cam

is there any other reason for this? scattered timing? my setting tappets wrong? overrevving? there was no contact evident last time i lifted the head

does this mean i have to get pistons machined?



there is also cracks between 3+4 just evident in the pic, i am not bothered if this engine is scrap what i am worred about in the new engine will i have to go back to mg rockers? with the ph2?

Edited by wolfie on 30th Mar, 2006.

How the F**K have you managed that on an A-series???

This is not possible as the valve has to lift at least (assuming a VERY skimmed head) 5mm off the seat before reaching deck level - and I don't know what cam can do that in the 50/60 degrees before TDC that it starts to happen - unless your cam timing is a MILE off ????

its possible dave i did not do the engine bought as is, its got steel lightened duplex gears and is clearly lightly rebuilt


would it not run though if the valve timing was out? it drove reasonable

Edited by wolfie on 30th Mar, 2006.

Is the timing chain still on to be able to check?? Seems very strange

-MINI CLUBMAN 1380 TURBO-

piper reccomend standard or 1.3 ratio rocker with the phase two.

I have a NA engine with std pressed steel rockes (highest lift) STR930 cam, and 13,5 cc head(skimmed lots), pistons flush with block deck. with this setup I am still 1 mm clear from the pistons with the valves.

.

Edited by fab on 30th Mar, 2006.

pistons may be ok , mine has had a bit of contact but that was through over tightened tappet when adjusting for the first time but it did just mark it rather than when running.

always looking for them bigger bunches of bannanas

Between 2 and 3 is the hottest part of the engine,if cooling is a bit lack could be the valves sticking a bit in the guides

Metro turbo weekend driver,Mini turbo in the making again!

Team Racing

i concer as wolfie told me that it was just 2 and 3 which was marked so sounds about right.

always looking for them bigger bunches of bannanas

i will go with valve seizure in the guides on 2 & 3

Created by fueling & or ..Ignition timing, too HOT!

for me the piston on the left shows signs of detonation and is starting to break up!

i would not trust these further IMO.

the above needs addressing on you next build.

what guides & valves were used wolfie?.

I had an exhaust valve pinch up on me. However the damage I got was much more severe (bend valve and very dented piston)

It would be well worth checking out your valve stem to guide clearances and making sure they are not too tight

Metro turbo weekend driver,Mini turbo in the making again!

Garranteed seizure, make sure those guide are well reemed especially if they are bronze.

JF.

What is it with Jon and reaming....

The man's obsessed!

hoggy reamed my hole so the shaft wont stick

cheers hoggie

yes they were tight on the reamer but didnt seam to bad with the valve in but should be ok now as long as that fuel and ign is correct.

always looking for them bigger bunches of bannanas