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| | | | Joined: Dec 2007 Posts: 210 Shop Shark | | Shop Shark Joined: Dec 2007 Posts: 210 | I have a regular head for a 235, not a 848,I have decided to have it milled and to sink the intake valves as some have suggested.I am not sure if I should have larger intake valves put in ,or just keep the ones I have.Would there be much gain by going to larger valve?I know That this engine won't make much HP,but would like a little increase if I can get a little.In a few years ,I plan to go to a 250,or 292. | | | | | Joined: Feb 2004 Posts: 29,742 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,742 | Larger valves don't help because of the terrible intake port shape. There are too many sharp turns and restrictive areas, especially in the intake ports, and even enlarging the ports doesn't help much, if any.
Increasing compression by milling the head will help the low end torque somewhat. If the duration and lift of the cam is increased, the added compression ratio just gets the compression pressure back to where it used to be before some of the compression stroke got used up by increased intake valve duration.
Jerry
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| | | | | Joined: Dec 2007 Posts: 210 Shop Shark | | Shop Shark Joined: Dec 2007 Posts: 210 | [quote=Hotrod Lincoln]Larger valves don't help because of the terrible intake port shape. There are too many sharp turns and restrictive areas, especially in the intake ports, and even enlarging the ports doesn't help much, if any.
Increasing compression by milling the head will help the low end torque somewhat. If the duration and lift of the cam is increased, the added compression ratio just gets the compression pressure back to where it used to be before some of the compression stroke got used up by increased intake valve duration.
Jerry
I don't know much about these older engines,other than rebuilding them,so this does help,and it's a long the same as I been thinking.I have done some work on small block V8 Chevys and was part of a crew that worked on a late model dirt track car.Run it on alcohol .This 235 ,is take it apart and put it back together kind of thing.I do have a cam that I had Howard cams reground for me.I told them my goal and then went with their recommendation .Again I depend on them to steer me in the right direction.It looks like my plan to mill and sink the intake valves is on track.
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