Could installing pistons backwards bend valves??

[krnbk2]

If a set of Ross pistons were installed backwards in a 4g63 (i.e. small valve reliefs positioned on intake side) would they interfere with the valves? My assumption is that they would and that is the reason why the intake valves need a larger relief but it would be nice to hear it from someone else.

*Edit* Forgot to mention, this is with FP2 cams (im not sure if this makes a difference because i dont remember if these cams push the valve further into the cylinder compared to the stock cams?)

thanks

 

[talonguy91]

I'm pretty sure by having them installed backwards would not be good, and that's why the reliefs are positioned and sized the way they are. My recomendation is to remove pistons and position them the way they should be, don't build half right because then you build twice plus you have peace of mind knowing it's installed correclty. Anyone feel free to correct me and good luck with your build.

 

[krnbk2]

I'm pretty sure by having them installed backwards would not be good, and that's why the reliefs are positioned and sized the way they are. My recomendation is to remove pistons and position them the way they should be, don't build half right because then you build twice plus you have peace of mind knowing it's installed correclty. Anyone feel free to correct me and good luck with your build.

Well it is a bit too late for that. I had the short block assembled by a rather reputable shop. not thinking I had to inspect the work done, I installed the head and did the timing belt only to realize after all 8 intake valves were bent and pistons damaged that they were installed incorrectly.

 

[ADrewzki]

I'm confused. You put the head and timing belt on and ended up with bent valves. I don't see how installing pistons backwards would cause that. Putting a timing belt on wrong will cause that.

 

[spoolup]

when you say putting the head on, did you align everything BEFORE even placing the head NEAR the engine? of did you get it on then turn everything to line up?

 

[krnbk2]

I'm confused. You put the head and timing belt on and ended up with bent valves. I don't see how installing pistons backwards would cause that. Putting a timing belt on wrong will cause that.

yes will if thats the case, than why did Mitsubishi or any other DSM piston manufacturer make the intake side valve reliefs larger and deeper than the exhaust side?

when you say putting the head on, did you align everything BEFORE even placing the head NEAR the engine? of did you get it on then turn everything to line up?

yes, everything was aligned correctly.


WHat im trying to get at here is if all things installed correctly would just having the pistons reversed be enough to bend valves, Assuming the timming belt was put on correct etc etc

 

[1fast97gsx]

It's hard to say, my guess would be at higher rpms it's a possibility. I noticed on the Ross pistons there isn't a considerable size difference between the reliefs, but there's still a difference and there's a reason for that. I suppose it also depends on if you shaved the head and/or block and also if you have oversized valves. That why I like wiseco pistons. Very large reliefs. I had a timing belt jump a few teeth with an oversized valve head motor and just had a horrible idle and the car would die out. I pulled it into the garage, inspected it, found the cause, replaced the failed part, retimed it and good to go. Blew perfect compression and no problems.