Hi Dave

My 140L (the one with the broken conrod, now fixed..) started to lose compression and subsequently power
two days before a competition last weekend. The exhaust valve was obviously leaking and grinding didn't help. Almost in despair [:@] I took the head off my new DZ and found it to be interchangable with the L if the injector fitting was blocked and the left rocker arm taken from the L.
This head does seem to have aluminum valve seats as opposed to the L head wich has copper (or something like it) inserts for the valve seats.

I am just curious, why this design change ? Are the alu seats hardened in any way ? Do they last
longer than the previous design ?

BTW the L ran super strong with the DZ head and the competition went quite well for me.

Oistein

We have had very good success with the aluminum valve seats in the DZ head. It is high silicon content aluminum. At the present time, we have some of the DZ engines running with over 500 runs on these heads with no problems.

Did you win the contest?

No I didn't win, but I came second after a very, very good pilot , also by international/WC standards.

Based on your experience, what do think about my 140L head assembly (about 250 flights) .... Do you think it is likely
that a new set of valves will solve the leakage or should I go for a complete new head assembly ?
If I order a complete "head assembly" does those include the rocker arms ?

Will a replacement 140L head have the new aluminum seats or do you suggest that I buy a DZ head (that I just have proved to work well in the L also) ..?


Thanks

Oistein

I think one of the reasons for the one piece head is to help prevent warping of the valve seats. I think I would replace it with a DZ head.