First, Hello to my old friends - after my long absence from this board.

Just won the bid on some 487X heads and will receive them soon.

Anyone have any comments for them? Anybody ever used em on street car?

These have only 1.94 intake valves, so I wonder what's the deal - They are supposed to have 2.02 when the "X" is shown in casting.
The seller said "X" means they have larger runners and include factory-hardened seats. I think B.S. but wait to find out.

Also, I will use them on 406SBC and must drill the holes using gasket as template. (They are from a 73 Monte Carlo with 350cid.)

Thanks for any words of warning or history of useage or recomendations for port work/unshrouding/screw-in studs, etc.

 

From what I have heard ovewr the years is that the "x" means 10 more cc's in the intake runner. The are good factory heads but they might be a little small for a 400, unless you port hem. And as far as I know they didnt have hardend valve seats b/c there was still lead in gasoline so there wasnt a need for it. Hope this helps

 

Thanks for the reply.... first thing on my list to-do is check port sizing intake and exhaust. Also, some differences on chamber size - some say 76 others say 75cc.

Of course I will mill them flat so it may become 74cc.... all fine and good for flat-tops in my 406.

Also, I read that Chevy heads starting in 73 all had the hardened seats.
So if the car is 73 I just wonder when the heads were made?
Also, does Chevy start hardened seats in Jan. 73 or July 73, etc????

 

1971 was when Chevy went to hardened seats.

 

The 487 casting was considered intermediate and high performance heads for 1971-72. They could come with 1.94/1.50 or 2.02/1.60 so you can easily upgrade to larger valves if you want. They were on 350's and 400's so see if there's any steam holes in the head indicating it was on a 400 block. These heads will have accessory bolt holes on the ends.

Not sure on the increased size of the 487X but a 461 casting had 165cc runners and the 165X had 170cc runners. If you're running in a class where you're not allow to port heads, an X casting if allowed would be the way to go. If not then a die grinder can easily give you a lot more runner.

Personally unless they were dirt cheap, I wouldn't spend the money on them. 34 year old heads with old technology. By the time they're upgraded with better valves and springs, new guides, screw in studs, larger spring pockets, porting, you're still stuck with old castings and a set of new Darts will be better right out of the box for less money in the long run.