Fuel question

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Skip
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Re: Fuel question

#16

Post by Skip »

So Mr. Cotten...port and polish only huh?...I too was told it (unleaded conversion) needed to be done, but I held out until now...glad I asked...Just bought a refurbished m74b I'm going to put on...I wanted to stay a pure as I could, so I put motor back stock...if you need speed, buy a twinkie...hate to see a panhead all butchered up with fake heads, fake cases, should be a jailable offense...Skip
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Re: Fuel question

#17

Post by Cotten »

FourthGear!
Modern additives are definitely contributors to gasoline going rancid.
An associate was cleaning out an elderly relative's garage, and brought me some old cans of gas (not only for proper disposal, but because I like old service station memorabilia.)
One or two smelled like varnish, but nothing like modern fuel after a year or two. One with great old art-deco font lettering upon it didn't smell bad at all, ... and my Datsun burned it without a complaint. (Usually old gas will make the exhaust smell bad, and run rough.)

Skip!
Porting and polishing a Panhead is like putting a scope on a sawed-off twelvegauge.
But back to topic, at risk of repeating myself,

Hard seats are intended only to reduce valve recession. The trade-off is valve seal, as tool steels change dimension when they reach critical temperatures. That's one reason why you will always find the low spot on a used exhaust seat is adjacent to the port.
The loss of seal due to distortion is far greater than what a bronze seat recedes under the same conditions.
If temps get high enough, the entire insert shrinks and falls out. Even a bronze replacement insert will not do that, as their coefficient of expansion is closer to that of the aluminum matrix.
The interference fit for a hard seat is so great that a tragic number of heads have been cracked beyond repair by the installation.
The factory knew that any insert would have to be cast - in.
When propane was introduced in the '80s for automotive engines, (zero lead of course), bronze was the material choice.
Hard seats became the automotive industry standard because induction hardened cast iron would spot weld to the valve head without the insulating effect of tetraethyl lead, along with the elevated combustion temps of low octane fuels.
High combustion temperatures means carbon deposits. The heads must be removed periodically to "de-coke" anyway, and betting upon hard seats to get you a few extra miles before an overhaul just means that the carbon will have scored the pistons and cylinder walls.
The petroleum industry's answer is just another putrid anti-deposit additive.
Spraywelding is definitely the way to go for seat replacement.

....Cotten
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Re: Fuel question

#18

Post by fourthgear »

How are the newer HD heads set up with as far as valve seats? I have been seeing Evo's and Twinkie's going past 100,000 miles with out touching them , seems like a normal thing now a days .
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Re: Fuel question

#19

Post by Cotten »

To me, a newer Harley is a Chubblehead.
For those, the Factory beefed up the casting to allow for a deeper insert, thus improving not only retention, but the heat transfer out of the seat and into the head.
Pans, however, cannot have the seats set in nearly so deeply, as they will perforate the intake port and cause an obstructive step in the exhaust port. (This step does not affect flow so much as it dumps heat back upon the casting instead of directing out of the motor. Early Chubbles had disasters enough from occluded ports that there were service bulletins instructing where and how to relieve them.)
Note also that the first years of Chubbles had hard seats, and then they went to soft in the 70's when lead was eliminated and combustion temperatures soared.

....Cotten
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Re: Fuel question

#20

Post by fourthgear »

Well I filled my tank with 89, just couldn't bring myself to try 87 yet , but I did not feel, hear or notice any diff. in performance . I had my old lady on the back so, I need to try with out her to see if any diff.. One thing I did notice , my starting procedure kinda changed, when stopping for more than a few min. , I would put the choke on about a quarter, now it seems not to need it . I know its not a scientific study and still only about eighty miles but , I've had the same procedure for over two thousand miles . How I noticed it was it would not start first kick as usual (and yes she fires first kick almost all the time) since we made a bunch of stops , I started just not putting any choke on at all (warm ) and she started first kick every time . I'm not going to say that is was the change in gas and I have to run her myself to see if performance has changed. Just strange.
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Re: Fuel question

#21

Post by Sidecar »

I too ran 89 octane for 250 miles this weekend. No noticeable difference. I'm going to run 400 miles or so the weekend of the 26th. I'll try a tank or two of 87 to see what happens.
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Re: Fuel question

#22

Post by Panhead Joey »

Hey Guys,

I shipped my 59 Fl Panhead rently to Ausstralia from the USA and was using the 92 octane fuel. The fuel grade/octane they use here are 91, 95, 98, E10 octane. So, the big question what will be the equivalent or desirable to use in Australia for the 1959 FL Panhead? I was told here that the 95 octane will be no problem so can I use the 91 or 95 octane?

Cheers,

Panhead Joey
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Re: Fuel question

#23

Post by Bigincher »

I'd love to be able to find 91 octane around here! Finding 95 is impossible. I'd run it and enjoy it while you can. (Wouldn't hurt to look at the spark plugs occasionally, make sure they have a nice color.)
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Re: Fuel question

#24

Post by Panhead Joey »

Hey Bigincher

Awesome I will throw 91 and 95 octane in the tank and see how she rides! Definitely, checking the plugs is a good idea and a good indicator how she's running.

Thank you!
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