Rave piston keeps comming loose

[n7188u]

I have a 99 Challenger 1800 and the PTO Rave valve piston (black cap) keeps coming loose from the valve stem on both engines, with the subsequent chewing of the piston's threads. I noticed that the threads on these two valves stems are worn down so I suspect that even when I used new pistons with fresh threads they simply broke loose and damaged the pistons threads.

I am getting new valves and pistons to eliminate this possibility but my question is how tight to make the pistons on the valve? There is no torque spec but maybe someone has an idea of how tight to make these.

Also, the left engine never goes over 5000 rpm. It could be the raves but the interesting thing is that the right engine has the same rave problem but it will go right to the 7K+ limit. What else can cause low RPM. Engine runs smooth at 5K, carbs were rebuilt although I pulled them out again to recheck them.

Chris

Chris

 

[seadooya]

5k on the left engine? Swap over the water regulator(rave looking thing, on the muffler), from the good engine muffler to the bad, and vise-verse...see now, if "good" engine, is peaking at 5k. Sounds though, your in need of a regulator...And for the raves tightening, i snug them up, finger tite

 

[n7188u]

I just wanted to provide closure to the issue of rave valve pistons braking loose.

The problem was that the threads in the stems of two of the valves were worn. The plastic piston would still screw and torque in correctly but it seems that the worn threads would overstress the plastic thread in the piston and it would fail.

Got new valves and pistons and all is well now (at least after running one weekend, which was enough before to make the piston fail).

Chris

 

[voodoo]

Is the rave filed to fit the piston size properly? The new slider part fits OEM size piston and must be filed open for each oversize.