Help!! Leaded Or Unleaded

Home  \  Classic Cars  \  Help!! Leaded Or Unleaded

i bought a 71 cutlass supreme with a performance 350 last summer and just got it running and its running really ruff and stalling alot and we would like 2 know does this take leaded fuel or not because my father or i are sure about this please comment asap thank you, Kevin Martin

posted by  71Cutlass

here's a quick check
look at the fill tube hole leaded pump nozzle were larger in size than unleaded this was to keep people from using the wrong fuel during the changeover to unleaded fuel you should be able to find lead substitute at most parts store's or some gas station's

posted by  osborste

we know a stock '71 would run on leaded, but i think it depends on the buildup of the engine.... what compression, cam, etc. olds 350, chevy 350 (crossbreeding--shudder)... did the rebuilder put hardened valve seats in or put on later model heads? on that subject, what is the general consensus on unleaded w/ leaded heads. i know there was a rush to hardened valve seats b/c the lead was gone, but i recall reading something lately saying that it was a scare and unleaded doesn't have that much of an effect on non-hardened valve seats... anyone?

posted by  dodger65

and i thought it was enviromentaly unsafe cause of the lead in it :banghead:

posted by  osborste

well that, too :doh:

posted by  dodger65

I know a couple of people who have just run their old cars on unleaded, then planned on replacing the valve seats if and when they wore out. .... Neither have had to do it yet, and they've both been running it for about 2 years. One of them does put in some of that fuel additive every third tank though, so I dunno if that's making any difference.

For anyone interested, the cars in question are an EH Holden (additive one) and an HQ Holden. ... both sedans.

posted by  windsonian

So, what does a gallon of leaded fuel go for these days? :banghead: :banghead: :banghead: :banghead:

posted by  DodgeRida67

i said the same thing about the poly 318 my dodge originally had, but i didn't use any additive. when i pulled it apart, the seats looked ok, but that was just one car i know of... i was just wondering what everyone else thought

posted by  dodger65

Three main things to consider:

A) valve seat recession;
B) swirl;
c) RON and MON.

posted by  Wally

right! so tell us about your engine, cutlass...

posted by  dodger65

I have been runnin a 350 olds for about 3 years now and it runs great on unleaded fuel. Im not gonna put my foot in my mouth sayin using leaded is not recommended because we all know these engines were built around leaded gas but just from my experience so far, the engine has had no problems. Hope you get it runnin!

posted by  neslorelyks

Your Message