Titleist16
Well-known member
If you backcut the valves do you need a bigger cam too or is the backcutting the valves enough? Which is better? I heard that backcutting is cheaper but will the valves wear out faster?
Bigger cam or backcut valves?
- Thread starter Titleist16
- Start date
I don't know what cam you have, but it really doesen't mater. Back cutting the valves with a 25-30 degree backcut only give you more flow, not only on the valve opening but on the valve closing, be it intake or exhaust.
Lap the valves to the seat then backcut to the lap in line.
The gain in flow is not only on the valve opening but also on the valve closing. The performance gain on a six would be probabally 4-5 hp, on a
V-8 possibly 10-15 HP. Every engine i build gets the back cut done, i don't care if its from a lawnmower engine to a race engine. The flow #'s speak for themselves. William
Lap the valves to the seat then backcut to the lap in line.
The gain in flow is not only on the valve opening but also on the valve closing. The performance gain on a six would be probabally 4-5 hp, on a
V-8 possibly 10-15 HP. Every engine i build gets the back cut done, i don't care if its from a lawnmower engine to a race engine. The flow #'s speak for themselves. William
Howdy titlelistI6:
How about both. The backcut intake valves will not wear any more than valves that are not backcut. The margin, or width of the seat, where the valve and the seat meet, must be maintained at about .100". The backcut occurs above that margin.
Backcutting not only increases flow, it lightens the valve train. We only recommend backcutting the intakes. Heat in the exhaust side adds another dimension of stress.
If you're only doing a valve job, add a back cut to the intake valves as another relatively cheap refinement.
If you're doing a complete engine rebuild, then add a performance cam in addition to backcutting the intakes.
Adios, David
How about both. The backcut intake valves will not wear any more than valves that are not backcut. The margin, or width of the seat, where the valve and the seat meet, must be maintained at about .100". The backcut occurs above that margin.
Backcutting not only increases flow, it lightens the valve train. We only recommend backcutting the intakes. Heat in the exhaust side adds another dimension of stress.
If you're only doing a valve job, add a back cut to the intake valves as another relatively cheap refinement.
If you're doing a complete engine rebuild, then add a performance cam in addition to backcutting the intakes.
Adios, David
