Do y'all with the older engines have to add lead or something to your gas? How exactly does running the engines that were built before the switch to unleaded gas work?

Wow, that question is grammatically amazing.

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What's that fuzzy blue thing being hurled this way?
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BOOSH!!!

I am no expert, but I think all the early 70s engines can run leaded/unleaded gas, or a mix of the two. I know my 74 can. If you have an owners manual, look in there. Thats where I found mine.

Note: The US did have all unleaded gas until the early 90s, but some late 70s and most 80s cars were only unleaded.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels

When I had the original 1965 engine in the car, I ran unleaded 87 just fine.
According to THOR, the only modifications made to the engines were actually in the head, making the valve seats harder.
Eventually, if I'd kept that engine (or if I resurrect it) I'll have to install hardened valve seats, but other than that, I don't believe any mods are necessary.

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<i>D'Artagnan</i>
<img src="http://img.photobucket.com/albums/v432/stephaniexchaos/dart/th_IMG_0326_zpsumhhfxi0.jpg">

You needn't add anything. Just keep the engine well tuned and read this thread.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

thanks. i was just wondering. my engine is from 73. so i wasnt worried or anything. i was just curious.

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What's that fuzzy blue thing being hurled this way?
::stick::
BOOSH!!!

My '74 Dodge was designed for leaded gas, and when Amoco stopped carrying leaded gas at the end of the '80s they put out brochures claiming that their Silver would prevent valve damage. After a few thousand easy highway miles on their gas I burned an exhaust valve. I discarded my Amoco credit card and have avoided them ever since.

The EPA published that you'd wouldn't fry valves on unleaded if you avoided "severe service" - digging deeper, I found the EPA defined "severe service" as towing, driving uphill or over 45 mph.

Since then, I use a Mn-based CD2 lead substitute regularly at the recommended concentration for my pre-75 cars & trucks and have never fried a valve. I can still find it at Walmart, but it's getting harder to find.

Nope. Unleaded. V8s for '72 and slant-6s for '73 got induction-hardened valve seats making those and all subsequent engines fully compatible with unleaded fuel. The cars didn't get catalysts until '75 to '79 (depending on model and market) so many vehicles were produced with full mechanical compatibility with unleaded but emissions compatibility with leaded. Your '74 was one of those.
Neither Amoco nor their fuel was responsible for your valve burning. It was pure coincidence.
You are wasting your money not only on the unnecessary additive, but on greatly reduced spark plug life. There was absolutely no material or build difference in the valvetrain of a catalyst-equipped '77 Aspen vs. your '74 Dodge.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.