unleaded vs leaded

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    Author Topic: unleaded vs leaded  (Read 2386 times)

    Offline r15303

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    unleaded vs leaded
    « on: August 23, 2006 - 04:22:52 PM »
    Can you guys tell me what needs to be done to an engine used to burning leaded gas to convert to unleaded?  I really don't have a clue and I would like to know at least the basics.  :clueless:
    Thanks
    Mark
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    Offline MEK-Dangerfield

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    Re: unleaded vs leaded
    « Reply #1 on: August 23, 2006 - 04:54:20 PM »
    Mark,

      There are lead substitutes out there. Are you wanting to rebuild the engine? I think the heads would have to be worked on at the least. Sorry I can't help more.  :-\


      Mike
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    Mike

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    Offline Bullitt-

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    Re: unleaded vs leaded
    « Reply #2 on: August 23, 2006 - 05:35:47 PM »
     :popcorn:
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    Offline ESGEE

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    Re: unleaded vs leaded
    « Reply #3 on: August 23, 2006 - 05:36:47 PM »
    Other valves and seats(or what its called on English), there are pretty much people here who done it. I go with the Substitutes :cheers:
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    daves70

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    Re: unleaded vs leaded
    « Reply #4 on: August 23, 2006 - 06:03:11 PM »
    You need to replace the valve seats in the heads with hardened seats. The old seats used lead to cushion them. Without lead the hardened seats will do just fine. :thumbsup: :grinyes:
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    Offline Chryco Psycho

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    Re: unleaded vs leaded
    « Reply #5 on: August 24, 2006 - 09:48:13 AM »
    the intakes will survive without Hardened [stelite] seats , the exhaust will not , the exhaust valve gets hot enough with the exhaust going past it that the Valve will weld intself to the seat & rip away the metal as it reopens , over time the seat can erode as much as 1/4 or more into the head
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    Offline r15303

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    Re: unleaded vs leaded
    « Reply #6 on: August 24, 2006 - 06:33:05 PM »
    Thanks guys.  The engine was rebuilt 3 years ago and has been driven 2-3 thousand miles since.  The car is new to me so I don't know what is going on with the valves.  Since the rebuild is fairly recent, should I be concerned?  You would think it was rebuilt with the correct valves and seats.  Should I use a lead substitute as a precaution or is there an "easy" way to check the valves without pulling off the heads?
     :feedback:

    Thanks
    Mark
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    Offline Chryco Psycho

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    Re: unleaded vs leaded
    « Reply #7 on: August 25, 2006 - 01:33:03 AM »
    a compression test or a straight edge on the top of the valve tips can give you a good idea if there is a problem
     lead additive cannot hurt
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    Challenger - You`ll wish You Hadn`t

    Offline moper

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    Re: unleaded vs leaded
    « Reply #8 on: August 25, 2006 - 06:44:30 AM »
    What CP said. Each rebuild (and rebuilder) is different. In most cases, guys who are selling the car dont do them. Because it's a few hundred more. If a guys racing the car, he wont, because fuel isnt a big concern. A cruise night guy might not, if his milage is very low. The erosion doesnt take place at low(idle) rpm, or under aceleration. It happens at light throttle cruise, when the mixture being burnt is lean. Exh valves should be upgraded to stainless, and the stellite seats installed if you have highway usage planned, or steady rpms are expected.
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    Offline r15303

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    Re: unleaded vs leaded
    « Reply #9 on: August 25, 2006 - 08:29:33 AM »
    PERFECT  This the the kind of info I need and why I can count on you guys for the straight scoop!  Now I can make an informed decision.
    Thanks
    mark
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    Offline duodec

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    Re: unleaded vs leaded
    « Reply #10 on: August 25, 2006 - 10:38:00 PM »
    Is it possible to get the seats in the stock early heads hardened the way the factory did it in later ones?  Or are replacement seats the only way of doing it?
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    Offline Chryco Psycho

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    Re: unleaded vs leaded
    « Reply #11 on: August 25, 2006 - 11:11:44 PM »
    you have to have hardened seats installed in the head
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    Offline duodec

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    Re: unleaded vs leaded
    « Reply #12 on: August 26, 2006 - 05:08:52 PM »
    Thats too bad.  Seems there should be a way to duplicate the factory procedure of induction hardening but perhaps its one of those things thats just too expensive to set up for except on very large scale production.

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    Offline moper

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    Re: unleaded vs leaded
    « Reply #13 on: August 28, 2006 - 07:01:47 AM »
    I'm sure you could do it, but you wouldnt want to. First, the hardening process only went so far into the iron. These cars could have gotten valve jobs (which really just meant cleaning and lapping "back in the day") that will erode the harder surface. Most sets I see now have at least one valve job on them already. Second, it was done with a ton of heat. So, the entire head would distort. That means re-machining everything. After it's treated..Including all the gasket surfaces. It's just easier to use a cutter, and pop in a complete seat ring, then just do the valve job.
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    Offline duodec

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    Re: unleaded vs leaded
    « Reply #14 on: August 28, 2006 - 10:14:37 PM »
    Moper,
         thanks.  Sounds like more than enough reason to do the replacement seats.  We'll just have to see how expensive it will be to rehab my old 318 heads (I'd like to keep them to keep the original engine as 'original' as possible, if its not ridiculously expensive).

    Rich
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