Slant Six Forum :: leaded to unleaded conversion

: I just bought a 64 valiant with /6 225. It is
: the first older car that i've had and I'm
: concerned about running unleaded gas in the
: engine. What (if anything) do i need to do
: to convert the engine? or should i just plan
: on using additive? any help is greatly
: appreciated

: '72-'76 heads came from the factory with
: induction hardened valve seats or you can
: have your machinist install hardened seat
: inserts when you get your next valve job.
: I've been driving a '66 Valiant for several
: years with no problems...but I don't get on
: it or run it hard much. I also haven't had
: the head off to look for recession---all I
: know is it's still running great and has
: good compression. I've heard a variety of
: opinions about how much of an issue this
: really is...maybe Doc will jump in and give
: us his view on this. He'll be the one who
: knows.

:
: Red did a good job covering the options, I
: agree that it is an issue to deal with when
: (if) the head comes off.
:
: The big tip-off for everyone running the early
: (pre 70) engines / heads is the valve lash
: adjustment, check the lash adjustment at
: least once a year, if the exhaust valves are
: getting tighter over use (less then .020
: hot) then the valve seat(s) are receeding
: and it is just a matter of time before you
: will have to do valve seat work. (my 66
: wagon is doing this, I've loosened the
: exhaust valves 2 times now, it has a factory
: induction harden "later" head but
: it is not enough protection for all the race
: car towing I do)
:
: For an early car which is running well, I would
: adjust the valve lash (to get a base line)
: and use additive, especially if you are
: taking a long trip on the freeway. You do
: not have to use the stuff in every tankfull
: and just a little goes a long way. (split a
: can between a couple of fuel loads)
: One interesting thing I noticed is that the old
: original engines which were run many years
: on leaded fuel seem to be more resistant to
: recession, I can only guess that somehow the
: lead gets into the seat surface and stays
: there a while. (note that there is leaded
: race fuel avaiable for "off road use
: only") ; - )
: DD

: Definitely use the anti wear additives. I
: don't know if any one brand is better than
: another, read the ingredients they're
: probably mostly the same. Here's my bit of
: non-clinical anecdotal evidence. I put an
: old style head on an Al slant 6 (newer
: styles don't fit) and used additve. I put
: about 35000 on the engine before I had to
: disassemble due to cracked block. There was
: no abnormal wear on the valve seats.
: Regarding late model cylinder heads, post '74,
: the induction hardening on these heads is
: very thin! They will not take a valve job.
: Some may disagree as to thickness, and I
: have heard that the hardened depth got
: thicker in later years, but the process
: itself is designed to give a hard SURFACE.
: Once that surface is ground away by a valve
: job, you now have soft cast iron and will
: need to install hardened seats.
: I leaned this the hard way when a Mopar
: Performance tech swore on all that was holy
: that a set of 360 heads would take one valve
: job.
: I did, didn't use additive, and after about
: 60k, when the power drop became too
: noticable to ignore (ie got beat by a
: Mustang GT), found that the exhausts had
: beaten themselves .100" into the head.
: Others may have stories of happier results, but
: I wouldn't bet my expensive engine on it.
:
: Bob Troy
: Santa Monica, CA

:
: I believe this topic surfaced on the
: forwardlook.net discussion board (55-61
: Chysler made vehicles) and the point made
: there was that engines that had many hours
: of operation running leaded fuel actually
: had lead imbedded valve seats. Therefore,
: due to this residual effect, they could run
: very safely on unleaded for an extended
: period of time. What's extended? Who knows .
: . . that's why I'd echo what's been said
: before. Drive away but keep track of exhaust
: valve lash changes.

:
: I have heard this as well, that the induction
: hardening is less than 0.010" thick,
: and so will likely be removed on a valve
: job.
:
: Lou

Author:	Andy Davis [ Sun May 19, 2002 11:58 pm ]
Post subject:	leaded to unleaded conversion
I just bought a 64 valiant with /6 225. It is the first older car that i've had and I'm concerned about running unleaded gas in the engine. What (if anything) do i need to do to convert the engine? or should i just plan on using additive? any help is greatly appreciated andy@adada.com

Author:	Red [ Mon May 20, 2002 5:20 am ]
Post subject:	Re: leaded to unleaded conversion
Quote: : I just bought a 64 valiant with /6 225. It is : the first older car that i've had and I'm : concerned about running unleaded gas in the : engine. What (if anything) do i need to do : to convert the engine? or should i just plan : on using additive? any help is greatly : appreciated '72-'76 heads came from the factory with induction hardened valve seats or you can have your machinist install hardened seat inserts when you get your next valve job. I've been driving a '66 Valiant for several years with no problems...but I don't get on it or run it hard much. I also haven't had the head off to look for recession---all I know is it's still running great and has good compression. I've heard a variety of opinions about how much of an issue this really is...maybe Doc will jump in and give us his view on this. He'll be the one who knows. ---Red

Author:	Doc. [ Mon May 20, 2002 9:19 am ]
Post subject:	Re: leaded to unleaded conversion
Quote: : '72-'76 heads came from the factory with : induction hardened valve seats or you can : have your machinist install hardened seat : inserts when you get your next valve job. : I've been driving a '66 Valiant for several : years with no problems...but I don't get on : it or run it hard much. I also haven't had : the head off to look for recession---all I : know is it's still running great and has : good compression. I've heard a variety of : opinions about how much of an issue this : really is...maybe Doc will jump in and give : us his view on this. He'll be the one who : knows. Red did a good job covering the options, I agree that it is an issue to deal with when (if) the head comes off. The big tip-off for everyone running the early (pre 70) engines / heads is the valve lash adjustment. Check the lash adjustment at least once a year. If the exhaust valves are getting tighter over use (less than .020 hot) then the valve seat(s) are receding and it is just a matter of time before you will have to do valve seat work. (My 66 wagon is doing this. I've loosened the exhaust valves 2 times now. It has a factory induction harden "later" head but it is not enough protection for all the race car towing I do.) For an early car that is running well, I would adjust the valve lash (to get a base line) and use additive, especially if you are taking a long trip on the freeway. You do not have to use the stuff in every tankfull and just a little goes a long way. (Split a can between a couple of fuel loads.) One interesting thing I noticed is that the old original engines which were run many years on leaded fuel seem to be more resistant to recession. I can only guess that somehow the lead gets into the seat surface and stays there a while. (Note that there is leaded race fuel available for "off road use only") ; - ) DD

Author:	Mitch [ Mon May 20, 2002 9:54 am ]
Post subject:	Re: leaded to unleaded conversion
Quote: : I just bought a 64 valiant with /6 225. It is : the first older car that i've had and I'm : concerned about running unleaded gas in the : engine. What (if anything) do i need to do : to convert the engine? or should i just plan : on using additive? any help is greatly : appreciated The rate of exhaust valve seat recession is governed by the valve temperature. Higher valve temps quickens seat recession. Basically, suatained high loads and engine speeds will produce faster recession rates. There have been SAE papers published on this phenomenom. I remember reading one where the recession rates were compared on a vehicle with unhardened seats. The recession rates were compared for two suatained speeds: one vehicle at 55 MPH, the other at 80 MPH. The slower car produced imperceptible recession while the other produced an extropolated seat life of 15,000 miles. Other than using additives (which I would), about the only things you can to to combat this is to back your spark timing off by a couple of degrees and make sure you are not lean. Like Doc said, periodically checking the valve lash will tell you what's happening. Mitch m5black@aol.com

Author:	Robert Troy [ Mon May 20, 2002 12:21 pm ]
Post subject:	Re: leaded to unleaded conversion
Definitely use the anti wear additives. I don't know if any one brand is better than another, read the ingredients they're probably mostly the same. Here's my bit of non-clinical anecdotal evidence. I put an old style head on an Al slant 6 (newer styles don't fit) and used additve. I put about 35000 on the engine before I had to disassemble due to cracked block. There was no abnormal wear on the valve seats. Regarding late model cylinder heads, post '74, the induction hardening on these heads is very thin! They will not take a valve job. Some may disagree as to thickness, and I have heard that the hardened depth got thicker in later years, but the process itself is designed to give a hard SURFACE. Once that surface is ground away by a valve job, you now have soft cast iron and will need to install hardened seats. I leaned this the hard way when a Mopar Performance tech swore on all that was holy that a set of 360 heads would take one valve job. I did, didn't use additive, and after about 60k, when the power drop became too noticable to ignore (ie got beat by a Mustang GT), found that the exhausts had beaten themselves .100" into the head. Others may have stories of happier results, but I wouldn't bet my expensive engine on it. Bob Troy Santa Monica, CA Quote: : : Red did a good job covering the options, I : agree that it is an issue to deal with when : (if) the head comes off. : : The big tip-off for everyone running the early : (pre 70) engines / heads is the valve lash : adjustment, check the lash adjustment at : least once a year, if the exhaust valves are : getting tighter over use (less then .020 : hot) then the valve seat(s) are receeding : and it is just a matter of time before you : will have to do valve seat work. (my 66 : wagon is doing this, I've loosened the : exhaust valves 2 times now, it has a factory : induction harden "later" head but : it is not enough protection for all the race : car towing I do) : : For an early car which is running well, I would : adjust the valve lash (to get a base line) : and use additive, especially if you are : taking a long trip on the freeway. You do : not have to use the stuff in every tankfull : and just a little goes a long way. (split a : can between a couple of fuel loads) : One interesting thing I noticed is that the old : original engines which were run many years : on leaded fuel seem to be more resistant to : recession, I can only guess that somehow the : lead gets into the seat surface and stays : there a while. (note that there is leaded : race fuel avaiable for "off road use : only") ; - ) : DD rftroy@aol.com

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Author:	Dart270 [ Mon May 20, 2002 3:05 pm ]
Post subject:	Re: leaded to unleaded conversion
Quote: : Definitely use the anti wear additives. I : don't know if any one brand is better than : another, read the ingredients they're : probably mostly the same. Here's my bit of : non-clinical anecdotal evidence. I put an : old style head on an Al slant 6 (newer : styles don't fit) and used additve. I put : about 35000 on the engine before I had to : disassemble due to cracked block. There was : no abnormal wear on the valve seats. : Regarding late model cylinder heads, post '74, : the induction hardening on these heads is : very thin! They will not take a valve job. : Some may disagree as to thickness, and I : have heard that the hardened depth got : thicker in later years, but the process : itself is designed to give a hard SURFACE. : Once that surface is ground away by a valve : job, you now have soft cast iron and will : need to install hardened seats. : I leaned this the hard way when a Mopar : Performance tech swore on all that was holy : that a set of 360 heads would take one valve : job. : I did, didn't use additive, and after about : 60k, when the power drop became too : noticable to ignore (ie got beat by a : Mustang GT), found that the exhausts had : beaten themselves .100" into the head. : Others may have stories of happier results, but : I wouldn't bet my expensive engine on it. : : Bob Troy : Santa Monica, CA I have heard this as well, that the induction hardening is less than 0.010" thick, and so will likely be removed on a valve job. Lou

Author:	Al T [ Tue May 21, 2002 8:54 am ]
Post subject:	Valve seats absorb Lead
I believe this topic surfaced on the forwardlook.net discussion board (55-61 Chysler made vehicles) and the point made there was that engines that had many hours of operation running leaded fuel actually had lead imbedded valve seats. Therefore, due to this residual effect, they could run very safely on unleaded for an extended period of time. What's extended? Who knows . . . that's why I'd echo what's been said before. Drive away but keep track of exhaust valve lash changes. ahtoews@shaw.ca

Author:	Andy Davis [ Tue May 21, 2002 9:39 am ]
Post subject:	Re: Valve seats absorb Lead
Just wanted to say thanks. This forum is great. Quote: : : I believe this topic surfaced on the : forwardlook.net discussion board (55-61 : Chysler made vehicles) and the point made : there was that engines that had many hours : of operation running leaded fuel actually : had lead imbedded valve seats. Therefore, : due to this residual effect, they could run : very safely on unleaded for an extended : period of time. What's extended? Who knows . : . . that's why I'd echo what's been said : before. Drive away but keep track of exhaust : valve lash changes. andy@adada.com

Author:	bud L. [ Tue Jun 11, 2002 10:13 pm ]
Post subject:	Re: leaded to unleaded conversion
Though I've never personally experienced valve seat recession, a few of my Mopar buddies have. I don't think it's a coincidence that they always coincided with severe useage and heavy valve spring seat pressures, and/or agressive cam profiles. This makes some sense, in light of one of the previous messages regarding SAE studies about said topic. I grind my own valves and seats, and the difference between grinding hard seat inserts and 'induction-hardened' seats is like night and day. You have to use special stones to cut the hard seats. Interestingly enough the hard seat insert stones are softer, so that they break down faster and expose fresh cutting crystals to the seat. Quote: : : I have heard this as well, that the induction : hardening is less than 0.010" thick, : and so will likely be removed on a valve : job. : : Lou fglmopar@aol.com

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