487 vs. 487x heads

John Scott · 11-29-2013, 01:04 PM

What is the difference between 487 and 487x SBC heads? If the guide calls for 487, can you use 487x?

Mike Taylor 3601 · 11-29-2013, 01:46 PM

Not sure about those heads off top of my head.I do remember that 461X had different cc runners. Should be able to look up in runner volumes on NHRA.com.
I don't think you can use the X castings unless it is listed in your casting # on engine specs.
Mike Taylor 3601

JRyan · 11-29-2013, 02:43 PM

The difference is that 487X heads have induction hardned seats and rotators from the factory. The 487's simply have a non-hardened seat and normal retainer.

Jerry

John Scott · 11-29-2013, 03:01 PM

Jerry, do you think you can use 487x heads if the blueprint lists 487? Are there engines that have 487x specifically listed as the head?

If you search classracer for 487 or 487x there seem to be some posts suggesting the 487x can be used for 1972 200hp 350. That engine doesn't have 487x listed. I'm gathering parts for a 1971 270hp 350 which lists the 487 and not 487x.

Greg Hill · 11-29-2013, 04:50 PM

I've had better luck getting the 993's to flow better than the 487's.

JRyan · 11-29-2013, 08:22 PM

Mac,

I simply don't know. I've never measured the cc's of a 487X to see how they compared to a 487, but I'm pretty sure the port sizes aren't as different as 461 and 461X's ( I think 7cc's now, and it used to be like 10 cc's different).

The casting dates on one of the 487X heads I have is 1971, so it could be that they were used on California cars which may have had a different EPA requirement for unleaded fuels in the early 70's that would have required the induction hardened seats. I think you'll notice on the head that the exhaust valve spring cup is deeper than the intake. They used the same spring on both int & exh., and just sunk the cup. That might have been one of the reasons for designating the "X". Later heads used shorter springs on the exhaust and the same cup depth.

All speculation on my part, but I'm sure there is someone out there that actually knows.

I'm with Greg on the 993's.

Jerry

11-29-2013, 01:04 PM	#1
John Scott Junior Member Join Date: Apr 2009 Location: New Brunswick, Canada Posts: 69 Likes: 1 Liked 0 Times in 0 Posts	487 vs. 487x heads What is the difference between 487 and 487x SBC heads? If the guide calls for 487, can you use 487x?

11-29-2013, 01:46 PM	#2
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,349 Likes: 298 Liked 248 Times in 87 Posts	Re: 487 vs. 487x heads Not sure about those heads off top of my head.I do remember that 461X had different cc runners. Should be able to look up in runner volumes on NHRA.com. I don't think you can use the X castings unless it is listed in your casting # on engine specs. Mike Taylor 3601

11-29-2013, 02:43 PM	#3
JRyan Senior Member Join Date: Apr 2003 Location: Aberdeen SD Posts: 645 Likes: 30 Liked 112 Times in 31 Posts	Re: 487 vs. 487x heads The difference is that 487X heads have induction hardned seats and rotators from the factory. The 487's simply have a non-hardened seat and normal retainer. Jerry

11-29-2013, 03:01 PM	#4
John Scott Junior Member Join Date: Apr 2009 Location: New Brunswick, Canada Posts: 69 Likes: 1 Liked 0 Times in 0 Posts	Re: 487 vs. 487x heads Jerry, do you think you can use 487x heads if the blueprint lists 487? Are there engines that have 487x specifically listed as the head? If you search classracer for 487 or 487x there seem to be some posts suggesting the 487x can be used for 1972 200hp 350. That engine doesn't have 487x listed. I'm gathering parts for a 1971 270hp 350 which lists the 487 and not 487x.

11-29-2013, 04:50 PM	#5
Greg Hill VIP Member Join Date: May 2006 Location: Louisville , KY Posts: 1,995 Likes: 68 Liked 279 Times in 68 Posts	Re: 487 vs. 487x heads I've had better luck getting the 993's to flow better than the 487's. __________________ Greg Hill 4171 STK

11-29-2013, 08:22 PM	#6
JRyan Senior Member Join Date: Apr 2003 Location: Aberdeen SD Posts: 645 Likes: 30 Liked 112 Times in 31 Posts	Re: 487 vs. 487x heads Mac, I simply don't know. I've never measured the cc's of a 487X to see how they compared to a 487, but I'm pretty sure the port sizes aren't as different as 461 and 461X's ( I think 7cc's now, and it used to be like 10 cc's different). The casting dates on one of the 487X heads I have is 1971, so it could be that they were used on California cars which may have had a different EPA requirement for unleaded fuels in the early 70's that would have required the induction hardened seats. I think you'll notice on the head that the exhaust valve spring cup is deeper than the intake. They used the same spring on both int & exh., and just sunk the cup. That might have been one of the reasons for designating the "X". Later heads used shorter springs on the exhaust and the same cup depth. All speculation on my part, but I'm sure there is someone out there that actually knows. I'm with Greg on the 993's. Jerry