461 and 461X heads - can I run both?

[Brian Monticello]

I need some expert advice. Here's my dilemma. I purchsed a set of 461 heads from a guy in Texas via the internet - one was cast in'63 and the other in '64. I don't care about dates so I figured this wouldn't be an issue.

Upon examination, I noticed that one was a 461x and the other 461 casting as indicated by an embossed X on the bottom of one of the coolant passages. These heads have been mildly ported and polished at the intake and exhaust but the bowl area is untouched. I read the archives and understand the the 461X intake volume is supposedly 175cc while the 461 intake volume is 160cc. Both have 1.94/1.5 and the intake (yes...intake) valves have hardened seats. The heads need new guides.

question: if I plan on blending the bowl or pocket porting these heads, will the fact that one casting is a 461x and the other a 461? The reason I ask is because the 461X heads supposedly have the extra volume in the bowl area. Will I be opening pandora's box if I attempt this?

My gut tells me to cut my losses and move on.

Thanks,
brian

[Mike M.]

Re: 461 and 461X heads - can I run both?

Brian: i wouldn't do any porting , polishing or grinding of any kind on the 461X as there is very little metal between the runners and anti-freeze. I had a pair that i wanted the local machine shop to install case hardened inserts (exhausts but your insert location is another issue). they refused and showed me a 461x they'd attempted to P&P and install inserts. they hit antifreeze. i try to steer clear opf heads that Bubba or grumpy jenkins or anyone else has done any trick work on. mike

[Joe L.]

Re: 461 and 461X heads - can I run both?

Brian-----

The 461X do have slightly larger intake and exhaust runners than the 461 heads. However, if these heads have already ben ported (and survived), then the chances are that they are pretty much "equalized" by now. I wouldn't touch them, AT ALL. I agree with Mike that 461X don't usually survive any serious porting attempts, so someone got lucky and their gain is your gain.

The combustion chamber volume of the 461X and 461 heads is the same---62 cc, nominal. I would leave them alone, too.

The likely reason that the intakes valve seats have inserts is that too many valve jobs got the intake seats too recessed into the cylinder head. So, inserts needed to be installed to save the heads. It's not necessarily a bad thing as long as no one "struck water" installing the seats (and, went ahead and installed them anyway). I doubt that the latter happened, especilaly if the heads have been run since the work was done.

If I were you, I'd go ahead and have the guides replaced, the heads serviced and install them, as-is. I think that they'll be fine.

[Clem Z.]

get them pressured tested for leaks

before you go any farther.