jim88iroc305

for you guys that haven't changed the internals for unleaded gas do you use lead additive and if so which one and how often?

I just picked up the 68 in sig and it made the 140 mile run from PA to NY like a charm on cheap unleaded regular 87 octane which makes me very pleased as punch. No ping no knock no nuttin which I find incredible for a 35 year old engine.

I have a Mobil station with unleaded regular 87 octane I will use but I'm wondering if I should be adding lead to gas occasionally.

Watcha think?

TIA

Lowend

Don't bother
1. Lead additives have such a small effect that they really don't do any good.
2. If the engine or heads have ever been rebuilt than there are hardened valve seats and the lead isn't nessicary anyways

jg95z28

I'm running my stock 67 on Union76 Super (92 octane). No pings, no worries.

jannes

The lead is not there for compression, that is what the octane is about. Higher compression - higher octane. Pinging comes from too high compression, that the octane can't handle.

The lead is there to lubricate the valves, and especially the exhaust valves. To be able to run an engine on unleaded fuel you have to have hardened exhaust valve seats.

So if you don't have hardened seats and run on unleaded you will eventually melt down the exhaust valve seats and they will start to leak.

Lead additives work as supposed. I have it in my car and it gives no problems. It is very cheap.

Jan

jim88iroc305

This is the explanation I was looking for. The motor is completely unmolested stock with 76,XXX miles on clock from lil ole lady, 35 years old, built to run on regular 87 octane "leaded" gas. Nothing has been done to the engine internals - nothing rebuilt or replaced - when time comes i will do rebuild to run on unleaded.

MasterEvilAce

Yep. We have an original motor in my dad's 67 Camaro, he uses lead additive every two full tank loads.

jg95z28

I've had more than one person tell me that lead additives don't neccessary work to lubricate the valves anyway. I can't even remember seeing them on the shelves recently. What product do you guys use?

bowtie-70

Lead was originally added to gas as an inexpensive way to increase octane. It had the secondary effect of lubricating the exhaust valve seats. Depending on how hard you run your car and how many miles you put on it, you will eventually develop valve seat recession on a car using unleaded with non hardened seats. I use a lead substitute in mine all the time. It is cheap insurance and adds additional cleaner to the fuel system.
I used to use Bardahl Instead 'o Lead. WalMart stopped selling that brand and now sells the CD-2 brand. Its concentrated and one container treats about 240 gallons of gas.

jim88iroc305

Gunk is $2.99 for 12.0 oz at local speed shop
RedLine was $6.99 for 12.0 oz