487 vs. 487x heads - Page 2

Adger Smith · 12-01-2013, 01:18 AM

Jerry,
Wouldn't it be bad to get tossed with a 993 head and they see that 487X on it when doing the CC's... Humm
I'm going to have to run that one by Wesley.

Dwight Southerland · 12-01-2013, 11:12 PM

Not unknown on SBC heads. I have seen 291s with 462 cast on the bottom water passage hole.

ron mattson · 12-02-2013, 03:01 AM

487/487x and 993 are all based on the same
Casting group, that is why some have dual
Numbers top and bottom. As far as flow I have
Seen more of a difference between individual
Castings than between casting numbers, have
Seen good and bad 487 or 993 just depends
On the casting more than the number.

Mike Taylor 3601 · 12-02-2013, 02:38 PM

Someone mentioned 487 487X having hard seat/non hardened seat and spring seat differences, I think if you look the non hardened seat version may have take the older style plugs 3/8 reach w/washer verses the later using .460 reach tapered seat plug, I recall hunting for those casting years ago and seems like there was some that use 3/8 reach and some used .460 reach.

I've seen alot of heads w/ 2 casting #'s all through out years.
I have question have a 291 casting that has date that is a mystery to me
It has a 5 for last digit of date code which would be 65 or 75 which neither match should'nt be 65 has accessory bolt holes in the ends which everything I know about did'nt happen till 1969 and don't know of anything having 291 casting in 75. Could it been made in 1975 and sold over GM parts counter?
Mike Taylor 3601

12-01-2013, 01:18 AM	#11
Adger Smith VIP Member Join Date: Dec 2001 Location: Texarkana Ark/TX Posts: 2,446 Likes: 575 Liked 880 Times in 311 Posts	Re: 487 vs. 487x heads Jerry, Wouldn't it be bad to get tossed with a 993 head and they see that 487X on it when doing the CC's... Humm I'm going to have to run that one by Wesley. __________________ Adger Smith (Former SS)

12-01-2013, 11:12 PM	#12
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 780 Times in 194 Posts	Re: 487 vs. 487x heads Not unknown on SBC heads. I have seen 291s with 462 cast on the bottom water passage hole.

12-02-2013, 03:01 AM	#13
ron mattson Member Join Date: Nov 2005 Location: cloquet mn Posts: 466 Likes: 17 Liked 67 Times in 30 Posts	Re: 487 vs. 487x heads 487/487x and 993 are all based on the same Casting group, that is why some have dual Numbers top and bottom. As far as flow I have Seen more of a difference between individual Castings than between casting numbers, have Seen good and bad 487 or 993 just depends On the casting more than the number. __________________ Ron Mattson 5015 STK

12-02-2013, 02:38 PM	#14
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,372 Likes: 354 Liked 307 Times in 103 Posts	Re: 487 vs. 487x heads Someone mentioned 487 487X having hard seat/non hardened seat and spring seat differences, I think if you look the non hardened seat version may have take the older style plugs 3/8 reach w/washer verses the later using .460 reach tapered seat plug, I recall hunting for those casting years ago and seems like there was some that use 3/8 reach and some used .460 reach. I've seen alot of heads w/ 2 casting #'s all through out years. I have question have a 291 casting that has date that is a mystery to me It has a 5 for last digit of date code which would be 65 or 75 which neither match should'nt be 65 has accessory bolt holes in the ends which everything I know about did'nt happen till 1969 and don't know of anything having 291 casting in 75. Could it been made in 1975 and sold over GM parts counter? Mike Taylor 3601