Valve seats and lead [substitute].

[lesingepsycho]

I was wondering, for curiosity's sake, if you have an original leaded-head that's been running unleaded fuel for sometime and has already started to experience a little of the problems associated with that, will running lead-substitute mixed in with the gas replace anything over time or fix any minor damage that may have occured?

I'm not actually asking on behalf of the Midget. I just had its head rebuilt with hardened seats. But I am asking in relation to one of my other older classic cars which still has the original 1966 heads on. It's starting to pop and crackle a little like warn/wearing valve seats. It still has lots of get-up'n-go and I can't really afford a head job right now so I'm wondering if the lead-substitute in a can will do anything or just waste more of my tight budget?

My thought is, common sense says that it will burn slightly hotter, helping to break up carbon deposits AND will leave SOMETHING behind to help fill MINOR valve seat imperfections. Obviously it's not going to plug a crater, but it can't hurt, right?

JACK

 

[DrEntropy]

Snake oil.

Toss some Marvel Mystery Oil in the gas instead. Mix it by following the recommendation on the can.

 

[Spridget64SC]

Simple answer. Not much help.

The exhaust valve seat erosion that occurs cannot be repaired with anything put in the tank. Additives in the tank could delay or slow down further erosion, pitting and cracking of the valve seats, but the only valid repair is actual seat replacement either by inserts or by welding. Inserts are a much easier option than welding. And, when done properly are totally satisfactory. Welding should only be done if a catastrophic failure has occurred (broken valve head and damage or sufficient cutting of the seat into the water jacket).

Lead substitutes predominately contain another metal (sodium/phosphorus/etc.) for the seat and stem lubrication function. Other transport materials (fluid) are similar to gas/fuel injection treatment recipes. That is why you get the "Touting" of benefits such as better mileage and performance.

Depending upon the existing condition of the cylinder head, the additive may buy you some time and it may not.

If deposits are there in the combustion chamber, loosening them up will cause some to pass by the exhaust valve and maybe get caught between the valve seat area. Wouldn't expect it to stay there long. The 1000's of exhaust valves I've pulled out of heads rarely show any materials actually on the seat itself. Either side, top of pistons, in the combustion chamber, port, exhaust header - yes.

HTH,
Mike Miller

 

[DrEntropy]

Longer, still not very helpful:

Tetra-ethyl lead was the "lead" in fuel and it was bonded to the benzine ring with more than just pouring it into the gasoline. "Additives" are a "feel-good" measure and therefore IMO, SnakeOil. Useful mostly to pad the makers' pockets.


This is the helpful bit:
If your wallet is a consideration, keep it in your pocket. Walk past the additives.

 

[spritenut]

But I have been running unleaded gas since it came around 20+ years ago and NEVER did any of the hardened seats or any of that other "snake oil" repairs for unleaded gas and I have yet to have any troubles.
Many old cars, many hard miles. All I noticed is that my spark plugs last longer
with unleaded fuel. But my fuel lines seem to melt with the new ethanol gas.

 

[jlaird]

Use the modern high pressure fuel line for injectors. Yea I know it is expensive but you don't need much.

 

[bthompson]

But I have been running unleaded gas since it came around 20+ years ago and NEVER did any of the hardened seats or any of that other "snake oil" repairs for unleaded gas and I have yet to have any troubles.
Many old cars, many hard miles. All I noticed is that my spark plugs last longer
with unleaded fuel. But my fuel lines seem to melt with the new ethanol gas.

I'm glad you brought this up first, cuz I didn't want to be the first to go there. :wink:
I've driven a lot of old American iron with cheapo unleaded modern gas over the years. A '56 Dodge, '68 Bonneville, '69 DeVille, etc., all of them daily drivers. Ah, I miss the days of cheap gas...Anyway, I never put any lead additives in them, and never had any head troubles at all. ('Course, I didn't drive 'em that hard, which may have been a contributing factor.)

 

[lesingepsycho]

Thanks for all the great responses. I'll try a few other things but it looks like I won't be bothering with the time and money of fooling with "lead-substitute"

JACK

 

[Hap Waldrop]

I'll add to this, many vendors over the years have talked about seat recession, and if you didn't do hardened valve seats then this would happen to you. While exhaust valve recession can surely happen, it not the most common issue associated with unleaded fuel and stock exhaust valve seats, seal is the real issue. Most folks do no real science to check performnce, sorry a compression test isn't science , a leak down test is. On MG Midget limited prep 1275 race engine we built, we did leak down testing pretty often to keep a check on performance and seal and we found something pretty troubling. Now mind you in the race engine we were running leaded race gas, but here are the results we found.

New engine with fresh head w/new valves and multi angle valve job, after short run period was leak down tested and found to near perfect, no cylinder showing over 2% leakage. After one race weekend leak down testing was done again, and here's where the ugly showed up, 20-23% on #2 and #3 exhaust valves. A first I thought oh well, lets pull the head and check the seats, re cut them and lap them and we should be good to go. Ok off to another race, came home did another leak down, back to 20%+ leakage on the same two exhaust vlaves and now #1 and #4 had dropped to the low teens, hmmmm something is going on here. So I went and saw my buddy that does my street seat work, and runs a head repair shop (He does Mike Millers seat work as well) and ask him, what's the deal. He said it's simple Hap, the cast iron seat were never designed to run unleaded gas, and even though you did a nice valve job and got them to seal for a short while and are now running leaded race gas the metal has already compromised by years of running unleaded gas. So we installed harden exhaust valve seats and then ran the engine 14 race weekends and never dropped below 2 % leakage. That did it for me, I was convinced importatnce of hardened exhaust seats not only for the street but also for racing. I don't care how much performance work you do to your engine if it's losing seal at the valves, you thrown money and horsepower away. #2 and #3 are always going to show leaky first because they share the same port on a A series engine, so twice the heat.

So there ya go, a real answer with real testing to back it up. Save your money on mechanics in can pipe dreams and get your head properly rebuilt with hardened exhaust seats when you can.

 

[PAUL161]

This is just my honest opinion but, running these old engines with the soft seats on unleaded gas depends on how you drive them. Assuming the seats are in top condition to start with, normal daily driving without hard acceleration and high engine RPMs, (High cylinder temps), The heads will last a long time before needing any attention. Lead additives, or so their called, are snake oils! I've used Marvel Mystery oil for years in the gas, amongst other things. Has it done any good? I don't know, but it makes me feel better knowing the engine is getting a top lubricant. Strange as it may sound, my plugs run a little cleaner when using it. My 17 year old Chevy truck, which just hit 200,000 miles and has had Marvel Mystery oil dumped in the tank about every three or four tank fulls, doesn't burn a drop of oil and still runs great. Is it the MMO?

Good question. I say drive the car like it's the love of your life, not like it's your worst enemy and it'll last a long, long time! PJ

 

[Spridget64SC]

Yep, Hap and I do use the same facility in Greenville for a lot of our valve seat work. They do a great job and don't mind doing the work the way we request. I often ask for custom ID's on the seats to help get the port and finished seat width just where I want it for racing purposes. I'm also real particular about making sure you measure each time to cut each seat so the seat comes out flush with the combustion chamber. That means setting up for each valve in each cylinder.

But I do want to put some things in perspective. The last BLMC factory authorized imported vehicle to the US with an A-Series head was in 1974. That's nearly a full 36 years ago. No induction hardened seats, no inserts, just MOWOG cast iron. Also, manually adjusted valves. A BIG variable there! Keeping the valves properly adjusted has a very big influence on seat condition.

While "NO lead" gas has been around since gas was first made (TEL - Tetra Ethyl Lead is an additive too! Admittedly added by the gas blender), most gasoline sold in the US (other than AMOCO's "White" Gas & some others) had TEL as an additive for its beneficial purposes for many years.

Induction hardening of the cast iron cylinder heads was used by most vehicle manufacturers as the response to the removal of TEL. Seat inserts as required in aluminum heads or fitted from the factory to cast iron heads was another answer. Today, a cast iron head is a real rarity on any gasoline engine. Valve seat inserts come in a number of different material mixtures as well depending upon the desired application.

The exhaust valve seat distorts in a cast iron head due to the uneven thermal expansion of the cylinder head. More so than the intake. Valve guides wear. Valve stems wear. Rocker pads wear. The rocker arm wiping action across the tip of the valve stem rocks the valve side to side and the valve itself does not seat in a circumfrentially equal and consistent manner. Take a well used head and blue up the seat and then cut slowly with some hand cutters (NEWAY type) and you will see what I mean. A worn cast iron valve seat is all over the place. If you have ever seen a poorly maintained 1970 Spridget cylinder head run on unleaded fuel, you would wonder how it ran at all. Pitting, cracks and erosion all around the seat. A properly selected exhaust valve seat cuts down on the warpage, but doesn't totally eliminate it. However, quality (Martin Wells or SBI) seats make a world of difference from the cast iron seat. You can see it and can feel it when you cut them.

So, bottom line from my perspective (IMHO), and for what is paid for it , is that fuel additives cannot repair already existing damage, but have their place when used properly in a preventive manner and in conjunction with a properly maintained vehicle. In the end, quality valve seat inserts are an order of magnitude better and more permanent solution to the unleaded fuel issue in older vehicles equiped with non-induction hardened cast iron cylinder heads.

Have a great weekend and drive something!
Mike Miller

 

[Hap Waldrop]

This is just my honest opinion but, running these old engines with the soft seats on unleaded gas depends on how you drive them. Assuming the seats are in top condition to start with, normal daily driving without hard acceleration and high engine RPMs, (High cylinder temps), The heads will last a long time before needing any attention. Lead additives, or so their called, are snake oils! I've used Marvel Mystery oil for years in the gas, amongst other things. Has it done any good? I don't know, but it makes me feel better knowing the engine is getting a top lubricant. Strange as it may sound, my plugs run a little cleaner when using it. My 17 year old Chevy truck, which just hit 200,000 miles and has had Marvel Mystery oil dumped in the tank about every three or four tank fulls, doesn't burn a drop of oil and still runs great. Is it the MMO?

Good question. I say drive the car like it's the love of your life, not like it's your worst enemy and it'll last a long, long time! PJ

Paul, your 17 year old truck has hardened exhaust seats


If anyone were rebuilding a head, why wouldn't they have hardened exhaust seats installed, it's pretty cheap and effective, and insures greatly improved valve seal, whether you are racing or street.

 

[lesingepsycho]

<span style="font-weight: bold">WOW! Thanks guys. That's the kind of "Scientific" response I love Hap!</span>

"So there ya go, a real answer with real testing to back it up."

I am totally for getting hardened seats and when I had my Midget done this fall, I definitely had them done. Truth be told, I was asking on behalf of my '66 Mustang that I recently picked up, all original with 103k original miles. It certainly <span style="font-style: italic">hasn't</span> been rebuilt and I don't have the budget to rebuild the heads on the 289 small block at this time. It'll definitely get hardened seats when the day comes.

I knew if I asked here I would get real answers and real responses from guys I trust. Yes, that'd be you guys, my fellow LBCers. :wink: Thanks again for great responses to a relatively simple though often contested subject.

JACK

 

[drooartz]

Truth be told, I was asking on behalf of my '66 Mustang that I recently picked up, all original with 103k original miles.

And the pictures are where? '66 Mustang is one of my all time favorites.

 

[jlaird]

I had a brand new 66 stang with all the good stuff. Boy would that car move. Even mama liked it, it was really nice above 90 mph. Think I paid 3600 dollars delivered. First new car I owned.

Hay, towed an airstream all over the west with that car, standard tranny and all. Never knew it was back there.

 

[tomshobby]

I know, not a Midget engine but, .........

A few years and 20,000 miles ago I had my TR6 engine rebuilt. I had a shop that builds a lot of race engines of various brands. I followed the voice of experience and had hardened exhaust valves only installed. For all the reasons already mentioned and because I could actually use seats that were a little larger on the OD and depth than if both intake and exhaust were installed. I also replaced the valve springs and installed bronze guides. And all valves with hardened ones.

And the work came with a 1 year guarantee. I doubt the guy would have done that (standard with all of his engine rebuilds) if he did not have good luck with what he did.

My Midget engine was rebuilt several years ago and never in a car so I will be tearing it down. Guess what will be done if it has not already been done?

 

[regularman]

My opinion, just drive it. I don't think most of these motors will ever get the miles on them to give that kind of problem. I remember in the UK when they were changing over to unleaded fuel and all the minis that were daily drivers because they were still selling them and they never had that kind of problem and those little cars got driven hard. I can personally attest to the abuse an A series motor can take and keep on going. Most of the problems you are going to have are going to be from sitting, not from going.

 

[Hap Waldrop]

My first car was a 65 Mustang coupe.

 

[regularman]

My first car was a 1965 Dodge Polara. About 5800 pounds and was made to ride 4 adults in the back and 4 in the front. Big old car. It had two (lighted)ashtrays in the front dash and one on each rear door and one on the back of the front seat.
Man did that car ride smooth, but that 383 engine sucked down the gas. I bought it for $75 and had to put $120 worth of tires on it first thing. You could almost see the air in those tires LOL. It was the 4 door version of this
https://www.1962to1965mopar.ornocar.com/grubere65.html
Its what made me go to the pinto and little cars. The Dodge got about 9mpg and the pinto got 30mpg and even with bigger cams and all still got in the 20s and gave good power, but back then no one made really good timing belts and the bigger cams would snap one at times, so you had to be good at putting one on at night with a flashlight LOL