Quote:
Originally Posted by Kennuck
I agree with this. I can smell an old carbed car a mile away but my Stock 5.3 without cats has no smell.
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Yes, when I say "these engines" I'm talking about the older MarkIV BBC and classic peanut-port-era 350 heads. The LS has a fast burn chamber that probably is much more efficient at burning all the fuel.
We also tend to have more aggressive cams in the older engines but a lot of LS guys wind up running factory cam profiles because the motors make enough power in stock form.
I can't prove the cylinder head is the difference, but my '69 Camaro with EFI still smells the same as the Q-Jet car. But it has a fair bit of cam overlap.