Good Morning everyone and Happy 4th of July!!

I am currently freshening up a 76 440 with 4006452 Heads. It ran good before I started
cleaning it up, no smoke at all. I have a pair of 72 3462346 heads, is there any benefit
to changing them out?

Thanks,
Jim

The 452 heads have hard seats for unleaded fuel, the 1971 "346" heads don't.
I'm sure there is very little or no flow improvement between those two heads

Nothing wrong with the 452's.

"This head has minor variations on the 346 casting from 1971, with differences associated with durability details such as hardened valve seats, improved crack resistance, and an enlarged guide boss in the valve seal area. The intake port remained unchanged from the 1971 346 casting. The exhaust port was never significantly changed and remained true to the form introduced back in 1967 on the 915 heads."

The 452 has been my choice for years. They flow as good as most any of the factory heads, plus as stated, they have induction hardened exhaust seats. I have run them on several healthy street engines over the years and have been happy with them.

This is an instance where members good intentions get $$$ for the original poster mighty fast. The "For the same amount of money to refurb your 452s you can gat new aluminum heads" tend to come out. But- I said But...If the guides on your 452s are good, heads have no damage no cracks- good valves good seats I say clean castings, hand lap the valves and seats. Add new seals and maybe new springs. Very affordable if your heads are not junk. A non priority in your case but none the less a fun option would be some mild cleanup and prep with rotary abrasives. (Mild sensible porting but NOT hogging out!)

452 heads have an induction hardened exhaust seat not much good after the seats have been ground, The 346 head is the same, look on the end of the 346 head for two raised strips, this346 head has the hardened seat.