Negative cant cylinder head
Posted: Mon Oct 02, 2017 11:00 pm
Good afternoon everyone! Bright and sunny with a gentle fresh breeze. Spring is sprung!
I have been on holiday travelling about the show for the week. This time I was on a train and had plenty of time to read (and admire the most excellent scenes we passed through). I came across something unusual. It was in cylinder heads design.
I came across reports and commentary about Ford pro-stock cylinder-heads. There were A460, B460 types and more besides. There was even a type known as “bastard pro-stock” (I’m serious, that appears to be the real name). The development rate seems to have been high, as different variants were prepared in succession. There was even an “experimental” tunnel port version.
There are some significant alterations in the layout of the different cylinder heads. Originally the valve angles were 13 degrees by 5.2 degrees cant on the inlet valve and 9 ½ degrees by 5.2 degrees cant on the exhaust valve. Later versions had 17 degrees by 6 degrees cant on the inlet valve and 4 degrees by 3 degrees cant on the exhaust. There was a 14 degrees by 4 degrees cant inlet and 4 degrees by 3 degrees cant exhaust next. Last came the “bastard” cylinder head type and this was different. Its valve angles were 11 degrees by – 1 ½ degrees cant (a negative value!) on the inlet and 3 degrees by 4 degrees cant on the exhaust. So there was a negative cant for the inlet valve. That is very unusual.
If I understand correctly a negative cant for the inlet valve means it is moving away from the cylinder centreline (in the cant direction) and also away from the exhaust valve axis. It would seem to be slightly pointing flow towards the cylinder wall. The head was successful in competition, so it worked. What I was hoping to find was a picture of the head and also why negative cant was employed. What was the reasoning behind doing negative cant?
Comments?
I have been on holiday travelling about the show for the week. This time I was on a train and had plenty of time to read (and admire the most excellent scenes we passed through). I came across something unusual. It was in cylinder heads design.
I came across reports and commentary about Ford pro-stock cylinder-heads. There were A460, B460 types and more besides. There was even a type known as “bastard pro-stock” (I’m serious, that appears to be the real name). The development rate seems to have been high, as different variants were prepared in succession. There was even an “experimental” tunnel port version.
There are some significant alterations in the layout of the different cylinder heads. Originally the valve angles were 13 degrees by 5.2 degrees cant on the inlet valve and 9 ½ degrees by 5.2 degrees cant on the exhaust valve. Later versions had 17 degrees by 6 degrees cant on the inlet valve and 4 degrees by 3 degrees cant on the exhaust. There was a 14 degrees by 4 degrees cant inlet and 4 degrees by 3 degrees cant exhaust next. Last came the “bastard” cylinder head type and this was different. Its valve angles were 11 degrees by – 1 ½ degrees cant (a negative value!) on the inlet and 3 degrees by 4 degrees cant on the exhaust. So there was a negative cant for the inlet valve. That is very unusual.
If I understand correctly a negative cant for the inlet valve means it is moving away from the cylinder centreline (in the cant direction) and also away from the exhaust valve axis. It would seem to be slightly pointing flow towards the cylinder wall. The head was successful in competition, so it worked. What I was hoping to find was a picture of the head and also why negative cant was employed. What was the reasoning behind doing negative cant?
Comments?