Hi, I have a 70 Vette and would like to know if I need a lead additive, motor is a 350/300hp. Your thoughts. And whats a good additive for increasing octane. Thanks, Jim

 

My advice is no, you do not need it.

These cars do not typicaly get used as daily drivers any more. They see occasional use and not typicaly a lot of hard usage. If you tow with your older car a lot or if you use a lot of high RPM constantly, you might need to be concerned. The heads you have now will probably be around long after you have sold the car. The 350/300 cam is very easy on the valvetrain and that helps a lot too. The additives are not worth the money and can foul up the plugs with the deposits they leave behind.

-Mark.

 

I agree. Other then towing we do not need the hardened exhuast seats or lead.

 

Thanks for the info on the additives, Jim

 

based on suggestions from other members I began using Maxlead 2000 to get rid of the nasty exhaust smell, and it works. is there any harm in using it in a 73 L-82 with the usual mods (see my signaure for a list). the exhaust smell used to be all over me and my clothes after even a short drive and the Maxlead made a big difference. i only drive on the weekends, a few hundred miles per month.

 

I started using a lead additive recently. It plugged my inline filter by leaving black particulate in the creases of the filter pleats. I am no longer using it.

 

My engine builder mention not to worry about valve recession, when it happens, if ever, you just have the hardened seats installed. The need for lead.

The octane booster usually is a point increase and not a number increase. IE. 93.2 octane is boosted to a useless 93.3 octane.

Either reduce CR ( I did) or reduce timing. Or of course add massive amounts of magic chemicals. Octane today sucks compared to then.

 

good info here...thanks

 

so basicly whats being said here is that i dont need to worry about putting a lead additive in my 69 vette? there wont be any valve damage with how little it gets drove (maybe 1000 mlies last year) and useing just premium gas?

 

Exactly. If you had a big block, the compression is high enough that in certain situations (going uphill mid-summer if you live in Texas, for instance), a lead additive is a very good idea to prevent pre-ignition (knocking) and so prevent damage. For a small block, it's not likely to be needed, and, as someone pointed out, most additives don't really do squat, anyway (though the real tetraethyl lead additives like Real Lead or MaxLead do make a significant difference in the octane).

JB

 

Don't use it. Not needed.

 

I use Lead Supreme (same as MaxLead 2000), for me it makes all the difference in the world.

My fuel mileage does goes up some, the car runs around 5-10 degrees cooler and I have no knocking running at 8-10 degrees advanced.

If you have a car that was produced before 72', the valve seats will recess if real TEL is not added to the car. The octane of todays gas in your 350 is fine and you should not have pinging problems; unless very heavy loads under higher than normal heat conditions.

I have had the same set of plugs in my 72' for a year or so and they have not fouled out at all. I do not ever get deposits in my carb, intake, plugs etc... I have the white/beige color in my exhaust - which to me indicates the engine is running just fine. My plugs get the same coloring too.

My two cents - by a bottle or two of MaxLead or Lead Supreme. Give it a try. It only adds about 35 Cents per gallon - see if it works for you.

Bill

 

The maxlead2000 looks like a good product. I went to there site http://www.maxlead2000.com/ and liked what I saw. I need it for the octane boost more than the lead lubricating properties. I had heard about them before but didn’t take interest at the time. With my new setup I will need to use something and this is what I am going to try. Thanks for the info, you helped again.

 

Um..... no experience of it with the Vette (it's an '81 so unleaded is fine), but plenty of experience with old bikes & cars. And I did a huge amount of research when leaded was banned here as I'm running bikes that need it. Cutting through all the BS took some time.

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The accepted story is that valve seat recession occurs under high temperatures (which rules out the intake) when the valve closes onto the seat. With leaded fuel there was a deposit left on the seat that "cushioned" the valve, or so we've been told. With unleaded there isn't and apparently the valve & seat can micro weld themselves together. When the valve is opened this minute weld is broken, transfering a smidgen of metal from one to the other. Over time the cumulative effect is for the seat to recess. DON'T WORRY ABOUT IT! In about 10 years I've not known one engine to suffer from seat recession in normal use. Interestingly, I never noticed anything said about towing causing recession, the problem was only under the extremes of heat when run constantly at high rpms. Even then it was only on the exhaust seats that it occurs (although plenty of people here were suckered into changing the inlet seats as well). Towing I could understand causing a problem with pinging occuring (the other thing that TEL prevented).
A far bigger problem with unleaded is pinging. I've had to fix many engines that had run fine for literally years on leaded fuel & had blown holes through pistons when introduced to unleaded. Admittedly, some of these had been modified & were running CRs up to 13.5:1 & were left at that with unleaded fuel We've all had to drop our CRs down, some also having to retard the timing a bit & many having to change carburation slightly. I can't find any solid evidence one way or the other, but it seems that unleaded fuel burns hotter than the old leaded fuel did. Apart from stories in the pub, or in magazines (who are always in the pockets of the advertisers) my personal finding is that engines that used to produce good honest amounts of carbon in the chambers don't when run on unleaded. Jet changes have far less of an affect on plug colour now than they used to with leaded & I had to fit an oil cooler shortly after leaded was banned as the running temp of the engine increased.
What we've found is that seat recession looks to be a myth on most engines. No doubt there's some around that suffer, but those of us running stuff from the 60's & 70's haven't noticed any sign of it. Nor do we know of anybody that has suffered it (apart from on the race track). I like to hear of some as a lot of people will have needlessly had hardened seats fitted. Has anybody noticed any SBC owners from the 60's complaining of seat recession?
Additives are needed in some engines & not others. See how it goes, if it doesn't ping then just run it on unleaded, if it pings then use an additive. There were lots of tests done by magazines & owners clubs here on the various things to hit the market & one that always passed the tests was Castrol ValveMaster octane booster. I run it in my bike (which pings like a b'stard on unleaded, but is fine on leaded) & it definitely reduces the pinging dramatically. It also makes the engine run a lot sweeter, it's not something you'd notice in a car, but when you're sitting on something bolted rigidly to the engine you notice every slight difference in running. There's a version called ValveMaster Plus that is advertised to reduce seat recession, but how I'm going to prove that one way or the other is a tricky one - I've not seen any hint of recession after several years of (sometimes hard) use.
What the tests all showed was that TEL was the best (not surprisingly) & the various additives came in behind it. Some were useless (most have disappeared) & the best alternatives used a couple of other metal compounds (Potassium & Sodium? Or was it Manganese?). Can't remember, but the Castrol product always showed well. Asking whether an engine needs an additive is a difficult one. You'll just have to judge by how it runs. An example are or 4 bikes: My 750 demands octane booster, my wifes doesn't. Her 500 demands an octane booster but mine will run as sweet as a nut on straight unleaded. Yet when we go to the owners club there'll be people arguing all night over whether a 500 needs octane booster! The difference between the engines is easy, they are running slightly different CRs. The octane booster isn't perfect. There's a limited number of places that sell leaded fuel & one is close to us. When we fill up with it the difference in running is immediately obvious - no pinging at all. With octane booster I can get it to ping if I try. The reson we don't run leaded all the time? It costs about $2-00/litre!!!!!

p.s. I'm a bit slack on changing plugs & have had the same ones for more years than I'm going to admit! Never had a problem fouling with octane booster in there. What I do is run the coldest plug that doesn't foul (to try and prevent pinging) so, if a booster lowers the burn temp slightly then maybe a plug could foul if it's at the borderline operating temp? Just a thought.