Topic: unleaded valves

[neil10]

 I'm using lead replacement with petrol  wandering if I realy need to if valves are hard anyway?

[old750]

I've also wondered if valve seals need to be changed as I've read in my mopar magazines that they would post 1972 or around there.

[Gordon]

The sohc4's do not nead leaded gas.

[troppo]

do a search on this one, i did and found that aparently all the SOHC`s are designed to run on unleaded.
i was a little worried about this too
cheers
troppo

[Big Jay]

Interesting. The valve seats are pretty soft, especially by todays standards.

Jay

[City Boy]

I can't refute newer seats are harder than old,however,in all my near 40 years of playing with the sohc units,I have yet to see one with bad seats from normal wear and tear!Maybe I'm just lucky.

[troppo]

Well i was wondering about whether i needed to run with an additive or not to prevent valve seat damage, so i did a search about it, like i told neil10, and found this post where gordon put it very clearly

http://forums.sohc4.net/index.php?topic=25808.0

i dont believe everything i`m told so i kept searching and the general consensus is that you dont need a fuel additive to run unleaded petrol.
cheers
troppo

[mark]

My downloaded 500-4 manual is missing the engine theory page, so I cannot speak as to the construction of those valves. The 350 twin book that I have says that those valves are faced with stellite; says nothing about seats other than instructions for cutting with hand tools. I haven't tried grinding any Honda m/c valves yet, but stellite is some pretty hard stuff. I would be surprised to find that the seats were something harder than cast iron.

As for the stem seals... if original, they are over 30 years old. All of the rubber pieces that I have removed from these engines have been as hard as rocks. I would not hesitate to replace them.


Happy trails.

[eurban]

As they say, the proof is in the pudding boys.  Leaded gas been unavailable in the US for more than 20 years.  These engines have been running fine on unleaded for a very long time.  And yes there is science to back up these results.  Honda used valve seats of sufficient hardness.