timing chain AND non-interference exist

[mjoekingz28]

Might be dumb but just wondering do these types of engines exist.


Sidebar: What makes an engine interference/non-interference and why would you build an interference engine?

 

[bdcardinal]

An interference engine will have piston to valve contact if a valve stays open and the piston comes to TDC.

You want it because it enables the engine builder / designer to have higher compression ratios.

 

[OVERKILL]

Originally Posted By: bdcardinal
An interference engine will have piston to valve contact if a valve stays open and the piston comes to TDC.

You want it because it enables the engine builder / designer to have higher compression ratios.


And more lift of course too

 

[Chris142]

A st0ck sbc wont bend any valves if the chain jumps.saw plenty of those in the 80s with a plastic cam gear.a 318 will bend every exhaust valve though.

 

[OVERKILL]

Originally Posted By: mjoekingz28
Might be dumb but just wondering do these types of engines exist.


Sidebar: What makes an engine interference/non-interference and why would you build an interference engine?


Sure they do, many SBC's and SBF's (and I assume SBM's) are interference. If the cam has enough lift for the valve to hit the piston when it comes to the top of the bore, then it is an interference engine. Valve size is also a player here.

 

[mechtech2]

Using multiple valves per cylinder reduces their diameter, and attenuates possible interference.
But there can be belt, chain, or gears, and have interference or non interference.
Note that with an inappropriate downshift, RPM can increase so violently that the valves can 'float' and hit the piston top, even on a non interference engine.

 

[artificialist]

I have dealt with the Caviler 2.2 OHV, and they are non interference, even though sometimes the timing set fails.

The other reason interference engines are made is because sometimes the piston has to have to be dished in such a way that the combustion flame dies out in the valve reliefs.

In the Fiatnutz channel he explains it: http://www.youtube.com/user/fiatnutz?blend=1&ob=video-mustangbase#p/search/0/B11UPfneqeg

 

[Papa Bear]

My '51 Ford "flathead" was non interference .....

 

[Chris142]

Originally Posted By: Papa Bear
My '51 Ford "flathead" was non interference .....
Ya it was

 

[JTK]

Cam in block engines with a chain are a mixed bag of interference / non-interference.

Today's OHC engines with chains are probably all crashers.

Joel