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Unleaded fuel or not ??

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Unleaded fuel or not ??


Post by hjans » Wed Apr 02, 2008 6:31 pm


I own a 59 FLH, and i don't know if the valves and seats are "unleaded"or not. Previous owner died in a carcrash.
Do i need to use lead-addition ? Some tell me because the HD is a low performance bike (???????????) it is not needed.
How can i tell valves and seats are unleaded or not ?

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Post by steve_wood » Wed Apr 02, 2008 7:03 pm

1. It might be difficult to tell what kind of valves and seats you have - even if you pull the heads off. Not sure you want to do that.

2. My machinist explained to me that going with valves and seats that were designed to run on unleaded simply meant you only had to re-do your valves every 25K whereas running "leaded" valves meant a valve job every 20K miles. Exact mileage may vary but you get the point. Guess it depends on how much you drive.

3. I use Fitch fuel catalyst in my vintage bikes. Apparently it does many of the things that lead used to do for gas. Cool thing about it is you buy the packages, drop them in the tank and just leave them. They don't need to be replaced, they increase horsepower (only slighty) and they prevent the gas from creating varnish. Not bad for $40.

I'd be glad to hear other comments....

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Post by 51Hog » Wed Apr 02, 2008 7:57 pm

This post is going to stir some S**T.
Just gas her up and go. I rebuilt my Lycoming 0290d2 (135 hp) 1950s pa20 Piper Pacer Engine. Just ground the valves and seats (originals documented in the log book). Did the bearings pistons, rings cylinders etc...
I ran that engine on unleaded car gas for 10 years-- 1800 hours (Engine is rated at 2000 hours between rebuilds). No additives.
(NO STC Either) Aircraft engines always think they are going up hill all the time. and at 2450rpm cruise. Take off is always balls to the wall until I reach about 1200 ft. They work hard and are air cooled. They are the same technology as our old Harleys of the same era. I have done the same with an 0320.
What I am getting at, is that I had NO Problems with either of these engines using No Lead gasoline and no additives. I built the engines and know exactly what parts went into them. There were no modifications to accommodate the use of no lead. Can, and will I continue to run vintage engines on Unleaded gas with no additives?---Yes
Can you do it? I don't know.
Bring on the flame

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Post by fourthgear » Wed Apr 02, 2008 9:17 pm

Go for it , just use the highest octane rating you can get .( I have seen no performance diff. between 87 & 92 octane , but it may be just un-perceivable, to me ) Used to use Marvels Mystery oil and some here do too.

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Post by Cotten » Thu Apr 03, 2008 12:57 am

Bronze seats don't need no steenking lead.

Installing "hardened" seats often leads to tragedy.


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Post by FlatHeadSix » Thu Apr 03, 2008 1:33 am

You don't need the lead and unless you are running 9.5:1 or 10.5:1 pistons, you don't need the high octane either.

Three rules:
1. keep the fuel mixture a little on the rich side
2. Don't run with the spark retarded, time it to factory specs and run at full advance.
3. Don't lug the engine


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Post by PanPal » Thu Apr 03, 2008 3:27 am

I still add Marvels most times after I fill up. I don't notice a difference either way. In my mind it's helping lubricate the valve stems a bit. Back in the early 80's I built a 327 425hp small block. It was about this time the they quit selling leaded gas at almost all the gas stations. If I ran straight unleaded, the engine felt like the valves started sticking when I got down on it. If I even added a little leaded gas to the tank it would take the pounding without complaining. Could have been other things happening, but I always imagined the valve stems gaulding to my guides. The pan runs fine with or without it and even with my 87 octane riding mower gas. I just add Marvels for peace of mind. I'll add it at least until I use up the case of Marvels I bought several years ago.

I would never spend my money in the valve seat conversion. It can be done and work, but many heads have been screwed up doing it. It's possible for them to come out if the motor would run very hot due to the need for maintenance. Headhog can repair the original seats, so why take the risk?

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Post by Cotten » Thu Apr 03, 2008 12:51 pm

Another note on "unleaded conversion" components:

Nitrided valves, soft cast iron guides, and seals are desireable for longevity.

(Original "chilled iron" or "carpenter steel" guides seemed to last forever in their day, but I know of no production since the early Chubble era. The Factory probably dropped them because they were hard to service in the field without honing equipment and expensive skilled technicians.)


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Post by fourthgear » Thu Apr 03, 2008 3:03 pm

I just got this from another sight , some interesting reading .

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Post by panhead » Thu Apr 03, 2008 9:08 pm

use the highest octane rating you can get
The highest we can get here is 98.

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Post by mogman » Fri Apr 04, 2008 12:57 am

Nice looking ride!!!

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conclusion ??????????????


Post by hjans » Fri Apr 04, 2008 10:18 am

Hi there

When i read the above comments i think i can conclude next :
On a "stock"-pan i do not really need to add lead replacer, but just in case and to be real sure it isn't bad to do so.
Rebuilding to non-lead heads is asking for sh#t to happen.

Ok ???



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Post by Jack_Hester » Fri Apr 04, 2008 11:03 am

I have owned my '59 FLH since '74 (when I got out of the Army). It has yet to be restored, and far from the good looking machine that you have. I run premium 'whatever-I-find' gas in it with no problems. In the hot Summer, it will ping a bit when loaded. Retarding the spark a bit solves that. But, I move it back to full advance when on level or downhill stretches. Enjoy your bike as it is, and know that the closer to stock that you run it, the more likely it will outlast you.


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Post by King » Fri Apr 04, 2008 12:56 pm


You have a beautiful machine there. I would just ride it and enjoy. Follow Jack’s sage advice and keep it as stock as possible not only will it out live you but it will start and run as designed.

If, upon rebuild, it is determined your valve seats are too recessed to refurbish, Don at Headhog is the man to repair them using the buildup method. Cutting out the old seats and pressing in steel replacements not the way to go for a host of reasons. And there is no evidence to suggest that unleaded gas is detrimental to the stock bronze seats.

Personally, I have found my 51FL runs fine on regular gas even with a fairly high compression ratio( ~9.0?). When it pings, as Jack said, I just retard it a bit. I run Harley 60wt oil all year round but others have had good results with synthetics and multi viscosity oils. I believe as long as you don’t drop below 50wt you will be fine. Frequent oil changing is critical I change mine each 25hours (~1000-1250miles) more often if I’m doing a lot of short rides.

If any problems crop up post them here. You will find that there are a lot of folks here that “have been there and done that” and are more than happy to assist.

Good rides


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Post by Cotten » Fri Apr 04, 2008 2:54 pm

With all due respect to the ultimate repair with HeadHog's overlay process,
there is nothing wrong with installing oversized valves for a new lease on life.

The Factory produced them at one time, and now nitrided versions are made by several manufacturers, such Rowe, Kibblewhite, and even Dixie.


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