Z head and O head on 1973 340

Z head and O head on 1973 340

Whew! Lots-O-questions. I’m going to split up the post and answer it the best I can.

go-fish said
I have a 1973 340 4 speed Duster

very cool....

The O head has 341891 B (5 is not cast) and the Z has 3418915. The O also has 360 cast into it. However, in 1973 the 340's had 3671587 heads but this doesn't mean the engine couldn't have got some 1972 348915 heads.

I’ve found a bunch of things depends on the date of the part released and the date the car was built. Fast forward these many years and what is stock and what has been replaced are two different things.

From the information I've seen these should be 1.88/1.60 valves. The rockers are 273.

‘73 should have those valves but not that rocker arm.

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Are these heads going to perform amazingly better if I took .040 off the surface and put 2.02" intake valves in?

No. The rise in compression is nice but not really a noticeable thing. The extra valve size is a minor help since the area under the valve hasn’t been addressed or maximize.

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The cam is 224/224 @ .050 and lift is .468. Would there be piston clearance issues by milling the heads?

You’ll probably have clearance. What do you have now?
If you don’t know... you might want to measure instead of gamble.

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Different head gasket thickness takes care of that, right?

If it is a stock engine with the stock gasket, the gasket will be .028. I have problems finding thinner gaskets. It’ll be a custom order to the tune of about a $100 per gasket from Cometic to get a thinner gasket.
A gain you’ll never see and be hard pressed to see on the Dyno.