Re: [Amc-list] E-85 Engine Design

[Tom Jennings <tomj@xxxxxxx>]

On Sun, 1 Jun 2008, Wrambler242@xxxxxxxxxxx wrote:

> Tom may be able to enlighten us on how the older engines valve seats hold up as I believe he plans to rebuild his wagons engine after years of propane use and many thousands of miles.
>   I don't believe propane has any more lubricating properties than E85 would or will.

>From my experience with street cars the valve-seat-wear thing
is a crock, gasoline or lpg. Valve timing has more to do with
cooling seats and lips than crap left over from combustion! Stock
valves have shorter durations and the valves cool better. Proper
ignition timing (advance) will save valve seats.

THere's no lead in gas any more, and all the scare stories
about old cars ruined by unleaded gas were all untrue. HOT
ROD or someone did a real test years ago and the result was 5%
worst case shorter life.

No fuel leaves "deposits" behind that would "cool
valves". Seriously, deposits would more likely HEAT seats by
insulating them.  THe valve spring would mash deposits outof
the way else they'd leak. It never made any sense.

My 232 propane motor was built by me in 1987 (a year before I
put it in the wagon, it was in my previous 70 hornet). As it
turns out, I will rebuild my other 70 motor and swap (minimze
downtime). But I will pull the head on the LP motor because I
can't stand not knowing what it looks like in there!

I recall asking about hard valve seats but I think they were not
available. (Funny, I just yesterday came across the receipts
for the parts and machine work for the motor. It was my only
car at the time and I brought the engine to the machine shop,
about 5 blocks away in San Francisco, on a hand truck down
the sidewalks!)

I imagine I have some valve recession from 200,000 miles without
being apart. It still runs great. I measured compression every
2 years since the early 90's, it's slowly declining.


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