leaded gas?

[towdriver80]

Sorry, this is kind of a weird question. I`m 25, and can`t even remember seeing leaded gas, no idea what it`s supposed to be used for. I just bought an 86 3/4 ton suburban with a 454. The manual said the heavy trucks 8600gvw and over, wouldn`t have cats and should run leaded gas. It said occasionaly using unleaded was o.k., but not exclusively. I know youcan`t get leaded anymore, is there a substitute? Is it really neccessary, or have they changed unleded gas since then? thanks!

 

[k20]

some racing gas' are still leaded I believe. There is also an additive you can add to your tank to replicate the lead additives. Not sure if its lead, or another chemical with the same properties.

 

[dremu]

Sorry, this is kind of a weird question. I`m 25, and can`t even remember seeing leaded gas, no idea what it`s supposed to be used for. I just bought an 86 3/4 ton suburban with a 454. The manual said the heavy trucks 8600gvw and over, wouldn`t have cats and should run leaded gas. It said occasionaly using unleaded was o.k., but not exclusively. I know youcan`t get leaded anymore, is there a substitute? Is it really neccessary, or have they changed unleded gas since then? thanks!

Ummm ... AFAIK damn near every engine made since the 70's has the hardened exhaust valves and whatever else to run on unleaded... you should be fine

-- A

 

[jeeptuff]

Ummm ... AFAIK damn near every engine made since the 70's has the hardened exhaust valves and whatever else to run on unleaded... you should be fine

-- A

You took the words right out of my mouth.

 

[Mad-Dog]

During the gas crunch of the seventy's (not the one were having right now) leaded fuels were phased out and mandated the use of hardened steel valve seats.

The lead was previously used to soften the blow of the valves slamming down against the seats and causing premature engine failure, newer hardened steel valve seats no longer require leaded fuels or additives.

 

[79k20350]

not only did it soften the valve seat when the valves closed but it raised the octane of the gas allowing for higher compression motors, and more power. In your case unleaded will be fine to run.

 

[towdriver80]

Thanks, guys. I thought 86 was a little new for needing leaded gas, it really suprised me to see it in the manual. I used to have a hard time passing inspection with dual exhaust and no catalytic converters, I can`t wait to show up with a truck that came that way from the factory!

 

[ntsqd]

Note that if the heads have been off for a valve job that you no longer have hardened seats. The factory induction hardened the seats, but a valve job usually grinds thru that hardening.
If a valve job was done using seat inserts then you have no worries.