The V8 Owners Forum -

When I was rebuilding my rover v8 3.5 I had two sets of heads. One set had been completely rebuilt and skimmed with a few new valves and unleaded guides. the other pair were rebuilt but had 5000 miles on them.

I obviously went for the completely fresh ones and plan on swapping over to the second set of heads at a later date.

The second set of heads have larger valves than the ones I fitted (I believe they were early), would I notice much difference between the two sets and is it worth changing?

Its all in a land rover so not exactly a speed machine, but am I missing out?

sounds like you have early heads and later heads unless of course one set of heads have had big valves put in (spark plugs will tell you)). Early heads are always worth getting rid of, not only are the valves smaller but so are the ports. The later heads make a fairly healthy boost in power specially when you consider the cost which is next to nothing for a set of SD1 type heads

Yes the spark plugs have a different reach in the heads with smaller valves. I will look to swap the heads out at some point then

I have them so need to get them skimmed and cleaned a little.

Cheers