Looking for X Head Picture

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The intake port on the right is the 587 port used in this test with 1.88 valve before any work has been done. The port on the left is not involved in any of the testing in this thread. It is a port that was ported a couple of years ago and peaked over 279 cfm. Bowl width on that one is 86%.

IMG_3683.jpg
 
Here's the 587 port with new 35/45/60/75 valve job. No other work. Flow test was number 1645 in the next post.

IMG_3690.jpg
 
And here's the final result after 15 minutes of blending/grinding from the chamber side. I spent about 2 minutes blending the bowl, about 8 minutes on the short turn and about 5 minutes on the walls at the apex and bowl. As can be seen in the pictures, the valve guide and the top of the bowl were not touched. The black carbon can still be seen where no grinding was done.

This little exercise is complete. So with a valve job and 15 minutes of grinding, a 915 J or 587 intake port can be equal to or better than a stock X head.

IMG_3697.jpg


IMG_3696.jpg


IMG_3694.jpg


IMG_3693.jpg


IMG_3692.jpg


IMG_3691.jpg
 
No porting in Stock.
And heads are not superseded backwards, so X heads are only legal in up to 71 model year.

Of course…….the X heads would still end up better than the retrofitted/upgraded 587 if you put that same 15 minutes into them.
 
My thinking with the 587 vs X heads is simply this. For a street car with iron heads the difference between the two options is 15 minutes per port. Both heads will probably need a valve job anyway. And this is easy porting - something most people that work with their hands could do. A cheap set of X heads is $500 bare. A cheap set of 587s is free.
 
The X head I was doing my experimenting on was here for more substantial rework, so I took the Liberty of doing some basic rework steps, and check the results before actually diving in to what they were here for.
This was the last test I did before the big rework started……

What I did was a basic clean up of the entire port.
Some amount of guide boss trimming, diminishing the hump in the roof a bit, laid the SSR back a little more, and opened the pinch to .980”.
Nothing “maxed out” though.
That resulted in:

Lift—— In
.100— 63.0
.200—127.7
.300—180.0
.400—228.1
.450—246.8
.500—260.6
.550—266.3
.600—260.0
 
Last edited:
PRH said:
The X head I was doing my experimenting on was here for more substantial rework, so I took the Liberty of doing some basic rework steps, and check the results before actually diving in to what they were here for.
This was the last test I did before the big rework started……

What I did was to do a basic clean up of the entire port.
Some amount of guide boss trimming, diminishing the hump in the roof a bit, and opened the pinch to .980”.
That resulted in:

Lift—— In
.100— 63.0
.200—127.7
.300—180.0
.400—228.1
.450—246.8
.500—260.6
.550—266.3
.600—260.0
Click to expand...
And this is before the big rework. That's turning into a nice port.

Is it fair to say that at this point it would not matter if you were working on an X, a J or a 587? Other than the 15 minute head start?
 
What’s the intake port cc of a decently ported 340/360 iron head ?
 
273 said:
What’s the intake port cc of a decently ported 340/360 iron head ?
Click to expand...
I've measured many heads and I have found them to be anywhere from 155cc to 160cc as cast.


170/175 cc is a fairly ported 260's cfm with good low lift in the 190's at .300.
There are variables.

Full is closer to 190 but usually around 185cc
 
Is it fair to say that at this point it would not matter if you were working on an X, a J or a 587? Other than the 15 minute head start?
Click to expand...

I wouldn’t say that, no.

I was chasing the flow backing up on a set of previously ported J heads and found water long before I got the SSR where I thought it needed to be.
That was layed back way less than what I’ve ended up with on X heads.
I’m not saying someone else can’t get there, but on the non-X heads I’ve ported, I haven’t figured out how to get the big number without laying the SSR back to where it’s likely quite thin.

That being said, I’ve had some KG cnc ported J heads here that were quite good, and that program didn’t take that much off the SSR.
My recollection is they had a bigger bowl and more work done around the guide/roof area.

I’d say if I did the same job to a J type head as what I did to get to 266 with the X head, the big number would end up around 10cfm less, because I wouldn’t be attempting to duplicate the X head SSR into the J head.
 
MOPAROFFICIAL said:
I've measured many heads and I have found them to be anywhere from 155cc to 160cc as cast.


170/175 cc is a fairly ported 260's cfm with good low lift in the 190's at .300.
There are variables.

Full is closer to 190 but usually around 185cc
Click to expand...
My X head is 165cc and the 587 with a 1.88 tulip is 157cc. Change the tulip to a nail head and it's 159cc.

Largest I have done on a 587 is 197cc without hitting water.
 

PRH said:
I wouldn’t say that, no.

I was chasing the flow backing up on a set of previously ported J heads and found water long before I got the SSR where I thought it needed to be.
That was layed back way less than what I’ve ended up with on X heads.
I’m not saying someone else can’t get there, but on the non-X heads I’ve ported, I haven’t figured out how to get the big number without laying the SSR back to where it’s likely quite thin.

That being said, I’ve had some KG cnc ported J heads here that were quite good, and that program didn’t take that much off the SSR.
My recollection is they had a bigger bowl and more work done around the guide/roof area.

I’d say if I did the same job to a J type head as what I did to get to 266 with the X head, the big number would end up around 10cfm less, because I wouldn’t be attempting to duplicate the X head SSR into the J head.
Click to expand...
This is exactly what I have been wondering and perhaps this is Moparofficial's experience as well. If the water jackets are different then the X head could very well be better. If the water jackets are the same and the 587 has a smaller bowl and apex area, then the argument could be made that the 587 is even better. It would be like a porter's casting that would allow the porter more flexibility to do what he wants.
 
PRH said:
I wouldn’t say that, no.

I was chasing the flow backing up on a set of previously ported J heads and found water long before I got the SSR where I thought it needed to be.
That was layed back way less than what I’ve ended up with on X heads.
I’m not saying someone else can’t get there, but on the non-X heads I’ve ported, I haven’t figured out how to get the big number without laying the SSR back to where it’s likely quite thin.

That being said, I’ve had some KG cnc ported J heads here that were quite good, and that program didn’t take that much off the SSR.
My recollection is they had a bigger bowl and more work done around the guide/roof area.

I’d say if I did the same job to a J type head as what I did to get to 266 with the X head, the big number would end up around 10cfm less, because I wouldn’t be attempting to duplicate the X head SSR into the J head.
Click to expand...
The roof needs to get higher in the j head because the apex or ssr peak is higher than a n X head. Thats the major difference. Like you, it's been my experience that I can remove a ton off the short side radius on an X and not even get halfway there before I hit water on a j.
 
Before:

IMG_3955.jpeg


Lift——In
.100— 63.0
.200—128.4
.300—180.0
.400—207.5
.450—215.0
.500—207.5
.550—207.5
.600—207.5
 
Anyone have pictures of a cut up X head? Sure would be nice to see those water passages.
 
After-

IMG_3700.jpeg


Lift—— In
.100— 67.8
.200—138.0
.300—196.0
.400—240.0
.450—253.1
.500—247.6
.550—248.7
.600—246.8

This is a T/A head, so I’m not keen on pushing the limits of the SSR on those.
I’ll trade a few less cfm for no holes.

Also, that’s more guide boss trimming than was done on the 266cfm X head.
 
Last edited:
PRH said:
After-

View attachment 1716446100

Lift—— In
.100— 67.8
.200—138.0
.300—196.0
.400—240.0
.450—253.1
.500—247.6
.550—248.7
.600—246.8

This is a T/A head, so I’m not keen on pushing the limits of the SSR on those.
I’ll trade a few less cfm for no holes.

Also, that’s more guide boss trimming than was done on the 266cfm X head.
Click to expand...
Iron guide boss trimming is the worst. Hate it.
 
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