LPG Valve Design

[aharcourt44]

I am currently converting my truck to LPG. I have rebuilt the engine from the ground up. Before I put it back together, are there any special considerations I should give to the valve seat? I have installed stronger seats in the head (inserts) to keep the seats from being beat out. I have also changed out the worn valve guides with new ones. Additionally, is there a particular type of valve I should be using? My current setup has a valve face of .093 @ 45 degrees. My stem cut has a length of .071(measured parallel to the bottom of the valve) @ 25 degrees. The bottom angle is 52 degrees.

I have been giving serious consideration to increasing the length of the valve seat to help with heat dissipation but cannot find any information regarding how much this well help or possibly hinder what I am trying to do.

Anyone with any expert knowledge in this area, LPG engines that is, please let me know your thoughts. On a different engine I converted, the valve guides wore excessivly and I am trying to find out why this happened. Any inisght would be appreciated.

 

[BigInch]

I think your looking for the Engine and Fuel Engineering forum.

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[ApC2Kp]

aharcourt,

There are differences from gasoline fuels with additives for valve cleaning and life extension, that might not be in the LPG fuel. Remember tetraethyl lead in the old formulas?

There are also various grades and formulas of LPG fuel. I think the LPG for forklift trucks includes a lubricant for the valves and upper cylinder areas. Possibly as many as 10 different grades of LPG. The agricultural LPG for crop dryers will burn in engines, but not provide the best life for your engine valves.