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65 classic 660 lead fuel additive questions

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65Classy View Drop Down
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    Posted: Nov/29/2016 at 2:31pm
I have a 65 classic 660 rambler with the 232 i6 3 on the tree. I was successful in getting the car too run and drive daily for awhile but now it sits with valve cover off and only back fires out of the carb when attempting to fire it. I was told that I should have been using a lead additive in the fuel and that I may have burnt a valve or something I was just wondering if my car would have had to have lead additive being a 65 and if it would cause serious damage if I did drive it daily without it. If so could I have the head rebuilt with modern components and reinstall and use unleaded pump gas? Another issue I've noticed is my intake/exhaust manifold is cracked I was wondering what the availability of these are i can post pictures oh the intake if needed any help or suggestions would be appreciated.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Nov/29/2016 at 5:44pm
The lead additive hype is a myth. Lead does help lube the valves, but not having it only has a marginal effect on wear... about 10-15% more. So if you went 100K before a valve job, you'd only go 85-90K without leaded gas. Engines that are run hard, such as race cars and heavy trucks, wear a bit more.

You can get a new manifold, or at least a good used one. Shouldn't be too hard to find, was used from late 64 to early 1980.  Now I'm not sure all will interchange across those years, but they will for sure if you get the intake with the exhaust manifold. You can even use a late 80-89 aluminum intake with the matching cast iron exhaust manifold.

The cracked intake might be the cause of the backfire, and it could have caused a burnt valve.

If it makes you feel better you can have the head rebuilt with valve seat inserts in the exhaust valves (they wear fastest), or both valves. That's not your problem -- though you could still have a burnt valve.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gelalthedamned Quote  Post ReplyReply Direct Link To This Post Posted: Nov/29/2016 at 8:18pm
Yep, cracked intake prolly...backfires out the carb is generally a lean condition & could be the manifold sucking air. Have you played with the idle mix to square it up? Once we found air leaks around the manifold gasket by spraying starter fluid in the intake, waited a few seconds, stuck a long lighter down the carb and lit it, closing the choke when pulling the lighter out...flames came out around ports that needed to be torqued in.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 65Classy Quote  Post ReplyReply Direct Link To This Post Posted: Nov/29/2016 at 9:50pm
Thanks for the advice and clearing up the lead additive myth for me I've taken alot of crap for not adding it. I'm hopefully towing it home tommorow and will be checking compression and I'll go from there. I'll update with findings. I'll be looking around for an intake what other vehicles had these motors that were more common than I could find in a bone yard?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Nov/29/2016 at 10:42pm
It's actually just the exhaust seats that suffer when there isn't any lead. The valve is very hot and micro-welds to the seat, pulling off microscopic pieces of the seat once the valve opens again. Also the valve is much harder than the seat, so any rubbing motion between them causes the valve to wear out the seat. Lead acts as an insulator against the micro-welding and as a lubricant against the scrubbing. Worn-out valve guides accelerate seat wear dramatically because they let the valve scrub against the seat more. Most engines with 90,000 or more miles have worn-out guides.

Engines designed for unleaded fuel have hardened exhaust seats that more closely match the hardness of the valve. This greatly reduces micro-welding and wear from the valve. Hardened exhaust seats started in 1975.

The scrubbing action of the valve against the seat occurs all the time. Wear due to this will be accelerated without lead. The micro-welding of the seat only occurs when the valve and seat are very hot, like when the engine is run under high speed and load like on a long highway trip.

If you're daily driving around town and not working the engine hard, then only a moderate increase in seat wear will occur without lead. If you're driving on the highway a lot and working the engine hot and hard, then seat wear will be greatly increased. I'd definitely recommend a lead additive for those conditions.

My 232 wore out its exhaust seats in only 15,000 miles because the valve guides were worn, the seats were not hardened, and I did a lot of highway driving without lead. It now had hardened seats.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote uncljohn Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2016 at 5:46am
The subject of lead additives may very well push a lot of emotional buttons, but my Donohue owned since 1979 by my self has never used a lead additive. I now have 105,000 on it and is one of 3 AMC cars that I own. All of which I don't bother with it.
It has been pretty much proven that lead might have an effect if the engine was exposed to sever duty such as being a truck pulling weight day and day out. But for light duty use? Would not be missed.

I personally have heard more stories about hardened valve seats once installed? Become in-installed causing a lot of damaged parts. I personally believe there are more important things to worry about then whether lead is important or not.

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2016 at 6:08am
Gelalthedamned, that is an "interesting" way to check for leaks, but I don't recommend it. Could cause some burns. I guess if the engine isn't running you have to do something other than spray around the intake though.

The intake may not be sealing. When bolting the bolted together iron intake/exhaust up to the block the four bolts holding the two together should be loose. Then start with the center bolts and work your way out. IIRC there are no direct center bolts, so start with the two closest to one end, then the other two (four in the "center"), then keep doing the same -- go back to the next in front, then next in rear, until you have them all. THEN tighten the four holding the manifolds together.

If you get the intake and exhaust you can use the manifolds from ANY carbureted AMC six since 1965 (some late 64 models with 232). So look for Concords, Spirits, Eagles, and Jeep CJs and Wranglers up to 1989. May have to rework the head pipe in the exhaust, but they will bolt on. The 4.0L six head has a bit different exhaust manifold -- the two center exhaust ports are totally separate -- so it won't fit. The intake can be bolted to even the older engine -- and the 4.0L entire head an be swapped. It's a popular swap, but really only worth it if you need to replace your head anyway.

Oh, one more bit of trivia -- AMC sixes never came from the factory with valve seat inserts. Instead, AMC induction hardened the entire surface of the head after the valves were cut. That process only hardened 1/16" (or less) into the metal, but that's enough.

As everyone here has pretty much agreed, non-hardened seats only wear marginally more unless you're running the engine really hard. Normal driving is fine, even occasional hard running. If you're cruising the interstates at 70+ every day, you might notice a bit of wear, but still only 10-20% more. The valves can be cut 2-3 times before the seats have to be replaced (or the head). As noted, guide wear is a bigger issue, but won't hurt to have the exhaust seats put in when head is in need of rebuilding (new guides). The seats CAN come loose if not installed properly, so there is some danger of damage. I've only heard of them coming loose in a friend's car -- a modern Chevy with aluminum heads and hard seats from the factory. So it can happen! I would think it's less likely in iron heads as the expansion rate of the hard seats and cast iron is closer than aluminum and the hard seat material.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2016 at 2:14pm
Originally posted by farna farna wrote:


Oh, one more bit of trivia -- AMC sixes never came from the factory with valve seat inserts. Instead, AMC induction hardened the entire surface of the head after the valves were cut. That process only hardened 1/16" (or less) into the metal, but that's enough.
Yes. I found out the hard way that if the seats have already worn enough that they have to be recut then they've pretty much already worn through the hardening. You cannot cut them much at all before you hit the soft layer. You can feel the cutter dig in when you get to the soft stuff.

Originally posted by farna farna wrote:

If you're cruising the interstates at 70+ every day, you might notice a bit of wear, but still only 10-20% more.
I respectfully disagree, Sir. My 232 definitely pounded out its seats from only 7000 miles of 70+ MPH highway driving and another 7000 miles of normal use. They were the factory induction-hardened seats that I recut once. I broke through the hardness layer on #1 and #6 exhaust seats but decided to rum them anyway. Sure enough, those two seats pounded out while the other four exhaust seats were fine because they still had their hardness. I had to pull the head off and redo the valve job properly after only 14,000 miles since a full rebuild.

All I'm saying is if you're running unleaded fuel and run your engine hard for lots of highway miles like I do, then you will ruin your exhaust seats pretty quickly, not 10-20% quicker. I pounded out soft seats in only 14,000 miles of my use. Somebody using their 232 for grocery runs will last longer, but I still think they'll be toast before 50,000 miles. Hard seats last 100,000+

Seats seldom come out if the proper interference fit is followed. My seats specified a .010" interference fit for my iron head and they took quite a bit of force to pound in with a hammer. Aluminum heads specify a greater interference, so installing them with iron head specs can definitely cause them to come loose. Every engine coming off the assembly lines of modern auto manufacturers has hardened seats in  both Fe and Al heads, and they don't come loose, so there is a right way and a wrong way to do it.


Edited by FSJunkie - Nov/30/2016 at 2:19pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken Doyle Quote  Post ReplyReply Direct Link To This Post Posted: Nov/30/2016 at 2:35pm
I've driven the living heck out of three 199, and two 232 engines for 200k+ miles each on unleaded fuel and never had any valve problems.  Chevys might need lead substitube, but AMCs do not. 
 
Note that Amoco Premium never had lead in it. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Dec/01/2016 at 10:17pm
HOT ROD did tests decades ago on this. they estimated possibly 5% shorter valve seat life, for non-hardened seats designed for leaded gas, run on nolead. and certianly it will have nothing to do with engines running badly, that's a separate issue.

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