v-tach

what happens if it goes on this year ?
is it true that the valves wont bend ?
thanks
v-tach

WallyP

There are people on this list who say that no 16-valve engine is an interference engine, and that the valves won't bend.

There are people on this list who say that they know of 16-valve engines that have had bent valves after a timing belt failure.

Take your choice...

FlyingDog

I think the general concensus is Euro=interference, US=non-interference. I know somebody with an 81 Euro (4.5L 10:1) that has snapped 2 belts and hasn't bent valves. From that example, I'd assume that an 84 US (4.7L 9.3:1) would be safe if it doesn't have excessive carbon buildup. Just to be safe, I'm also assuming that my car (4.7L 10.4:1) would crunch valves if my timing belt breaks.

jserio

This is a good thread. I do not understand why a Euro 16v would be any different from a US 16v. Can anyone enlighten me.

FlyingDog

Higher compression means there is less space between the piston and head. That gives the valves less room. Euros (I think) also have greater valve lift which makes them even closer.

928ntslow

Not sure if this helps, but maybe checking the harmonic balancer for a 45 degree mark....if no mark, it should be a non interference engine. Just guessing here.

Pfunde

Broke the timing belt on my old euro 928 78 ( 4,5 L 240 bhp ) doing 120 mph and nothing happened to the valves.

rixter

best I can tell thru research is that the 77-79 8.5:1 compression engines are non-interference
of course this all depends on carbon buildup
not sure I'd like to be the one to find out

randy803

Back in my days of being a porsche mechanic I remmember seeing several that were fine after a belt broke but I also remmember a few that bent the valves. What you have to understand about Porsche is even though the books say the engines were the same each year for a range they still made minor changes. I just proved this to a friend of mine when I put two 1986 heads from differenty cars side by side one produced in early 86 and one produced in late 86 and the intake ports were cast larger on the newer! OLD 1.650 NEW 1.950 thats a big difference for something everyone thought was the exact same, so be carefull you might not slam a valve but the again......

jpitman2

I have personally seen an 84 Euro (10.4:1CR, twin dist) that broke cam nose on LH cam, and bent 4 valves that side.....Dont think we see any US 84s down here.
jp 83 Euro S AT 48k

Rich9928p

My '79 hybrid track 928 has an '85 block with '80 - '83 Euro S heads and cams. When the driver side cam broke, valves on both sides bent. OUCH.

So, why take the risk? Either you maintain a 928 or you don't, and if you don't you'll pay for it many times over.