what are x heads and how can you figure out if you gottem?

IQ52 said

Remember how the later 440 blocks were branded as having thin cylinder walls? Remember how that was proven to be false.

Sorry folks, you can file how wonderful the X heads are, compared to other heads, in the same folder with the thin walled 440 blocks.

Sad but true, you can start with a 1.88 J head and blow the best X head outta the water.

Click to expand...

LOL... Was thinking the same thing. My guess is they got their reputation because the early high comp 340's ran real good and by the time J heads came out Ma was using smaller cams and lowered compression so a lot of guys related the lower performance to the J head, which was incorrect. I had a set of 2.02 X heads and 1.92 J heads and the J heads flowed slightly more even with the smaller valves. I noticed looking into the ports the J heads were actually smoother. The X heads had more casting boogers. Don't know how much it impacted flow but I'm sure it didn't help.