oilplantman
Newbie
I've replaced my engine in my RX1 the old one had a catastrophic valve failure, the head of the valve came right off, trashed the head, piston and block completely. What would have caused this? I ran about 95% c-12 when it failed and I believe further back in the posts I read that running to high of Octane for the boost could cause this type of failure. Anything to that?
In my new engine I'm running an aggressive head shim (9-1 compression)and timing setup for it. I also installed a knock sensor on the new one I don't want another failure. I'm set at 7.5lbs on a gt20 turbo powderlite front mount, any other pointers other than not riding it to keep reliability? Should I downgrade to premium and 50%c-12 to keep from getting a blow torch effect?
In my new engine I'm running an aggressive head shim (9-1 compression)and timing setup for it. I also installed a knock sensor on the new one I don't want another failure. I'm set at 7.5lbs on a gt20 turbo powderlite front mount, any other pointers other than not riding it to keep reliability? Should I downgrade to premium and 50%c-12 to keep from getting a blow torch effect?
DC5
TY 4 Stroke Junkie
At that compression ratio and boost you can definetely run strait premium pump fuel. You could probably run 87 octane.
oilplantman
Newbie
Could that high octane fuel have caused the valve break? I'm leaving for McBride on Saturday and half the guys don't want me to take my Rx because of the reliability issue I'm hoping I can at least get one full ridein for $20,000.00 I hope any way.
Ted Jannetty
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oilplantman said:
Valve failures are usually related to valve springs that are weak or overheating of the valve from too lean a mixture depends if it was an intake or exhaust valve.
4strokes are better than2
Expert
you should be able to run up to 10-12 pounds on pump gas with that set up.you should give these guys a call- http://www.alpinemotorsport.ca/view_pho ... d=1157they would be able to give you exactly what you can run with your set up all there info has been great for me. 
Trxster
TY 4 Stroke Junkie
When you shimmed the head......did any of your valve lifters and shims come out??? Those littel shims are slippery and if they went down in the valve train that is exactly what would have happened!!!
Rt
Rt
hottshot
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Trxster said:
WHAT HE SAID!!!
oilplantman
Newbie
To pull the head and put the shim in Would the valves have to be pulled? I thought that the shim could be installed without stripping the head down. just pull the timing chain and yank the head?
Trxster
TY 4 Stroke Junkie
I am not sure about your shim kit but when you yank the head, if any of the lifters fall out (they are not held in by anything) the little spacers/shims that go under the lifter could fall out and if one of those buggers ended up in the valve train you would eventually pass it through your valve and #$@^$@#!!!. This has nothing to do with removing the actual valves. They are really small and oily and hard to find (I know). If all you did was pick up the head, put the gaskets in and put the head straight back on then that probably didn't happen but if you flipped the head over to clean your valves it may have fallen out. Wish someone would have explained it a bit better to me before I took mine out.
Rt
Rt
snowy1
TY 4 Stroke Guru
the way I read his post is the valve failed on a stock motor with out shim, and now he installing shim, if that is the case the shims had nothing to due with the valve failure.?
oilplantman
Newbie
No the first motor had the thicker head gasket and the timing was set up accordingly.
oilplantman
Newbie
Does a valve failure ie.. the shim falling out happen instantly or over a short period of time? Only one valve failed by the sound of what I was told so?
4strokes are better than2
Expert
this happened to a few other guys & it seems to happen over a short period of time & it dosnt matter how much boost or oct fuel it will go boom if this happens.
Travis Moore
Expert
Some of you guys need to be careful with your octane. Yes, far too much octane is not a good thing, but it's not going to damage your engine. There was a thread on here before where some guy thought it burned his valves or something but i simply do not beleive it. Run a few extra points and be safe! For what it's worth, i have ran been running 11.5 psi on AVGAS all season with no problems(compression is still perfect). AVGAS is right around 105 motor octane.
