(Captain Wubba) wrote in message . com...
Hi Cap,

I owned a '59 straight-tail with the O-300 as did my flying buddy.


1. What kind of fuel burn do you consistently get with an O-300? Is
the generally reported 105 KIAS @ 8 GPH true?

That would be right on the money.

2. Does the autogas STC help reduce the problem with valve sticking?
If you have the STC, do you generally burn a mix?

It did for me and my pal. We both experienced valve sticking when
burning 100LL. Using the rope trick to de-gunk a valve was almost an
annual occurence. Autogas made the problem go away. I used straight
autogas at home, but often had to mix with 100LL on XCs.

3.In general, has your experience led you to expect to have to do a
top overhaul about halfway through the TBO period? What are the
ballpark costs of such an operation.

Our experience was that the cylinders did not seem as robust as
their Lyc. counterparts, but that was back when overhauled cylinders
were commonly used and you had no idea how much TIS they had. Over a
3 1/2 year period (about 500 hrs.), I had one cracked cylinder and 1
with broken rings at around 1200 hrs. My friend had 3 cracked
cylinders between 900 and 1200 hrs.

4. In your opinion, would it be worth it to pay the premium to buy an
new 172 equipped with the O-320E2D?

I expect you meant to say "newer" above, since new 172s are equipped
with IO-360s. I think it's a toss up. The O-320 Lyc. (particularly
the 80 octane version from '68 - '76) has a history of sticky valve
problems too. The real upside to the Lyc. is that it's a few thousand
$s cheaper to overhaul. It's not as smooth as the O-300.

5. Besides the valve guide and cylinder problems (often attributed to
running on 100 LL), are there any other major problems that would make
this an undesireable aircraft?

I think they are very desirable aircraft. The only drawback for me
was that I like to do a lot of backcountry flying. The 145 hp was a
little weak for high altitude mountain strips in the summer time.

Also, while it does not make the aircraft undesirable, the O-300 is
much more prone to carb icing that the Lyc. After you've been flying
behind one for awhile, recognizing and clearing carb ice becomes
routine.


John Galban=====N4BQ (PA28-180)