487 vs. 487x heads
 

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

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

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

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.

Re: 487 vs. 487x heads
 

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

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

Re: 487 vs. 487x heads
 

I think the 993's are better than the 487's

Re: 487 vs. 487x heads
 

Interesting...thanks guys.

Re: 487 vs. 487x heads
 

Jerry,
Figure this one out.
I have a core supplier that hunts castings. The DT racers around here like the 487X head. He said he had several sets of castings that had 993 on the VC side, but in the water passage hole in the deck it had 487X. Could it be the lower part of the mold was for the 487X and they just mated the 993 top of the mold to them? Economy measure by the casting foundry? Use what they had available? I've always thought the X stood for a blueprint change. I wish I had some of thos 993/487X castings just to look at. Humm...

Re: 487 vs. 487x heads
 

Adger,

I just looked at one of those 993/487X heads today while arranging my storage. I think they're close to being interchangeable being they're both hard seat heads. GM must have thought so too as they interchanged molds for both as I've seen 993 in the VC area and 487X on the intake runner too. Some of the 993's also have a 493 on the bottom.

Also, I've had a pair of 993's with 152 cc runners. I'll bet the boys with the "Cheatin Bastards" would like those.

Jerry

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.

Re: 487 vs. 487x heads
 

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

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.

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