I'm working up a set of #452 heads for my 440 bracketcar and I would like to backcut the intake valves. Can someone tell me how wide the backcut should be ? The valves are 2.14 with a 45 degree seat angle. Thanks Paul

Never ground a valve in my life, so take it for what it is worth: I believe the backcut width is a function of the valve face width and back cut angle. Professionals might not share their angle as it makes a difference, but you probably won't go wrong with 30°.

Thanks for the reply. So far 30 degrees seems to be a "standard" but I want to make sure that I don't remove too much of the seat angle. I've done a lot of study on this but have found nothing regarding back cut width.

The back cut width will be different for two different valves. So there is no one answer.

The 45° valve face width is somewhat a function of the seat width and location. If you want/need a 0.090" valve face width and the back cut at 30°, the back cut width will be what it will be.

Thanks. This backs up my thought of removing the material which is beyond the seat width.

I usually bring the back cut to within .015 to .020 of the valve seat. I usually use a 33 degree angle.
See pic.

We could not take off much due to the Edelbrock valve job on these E heads but the 30 degree back cut on the intake valves helped a little at low lift..

Thanks everyone for the input. My valve grinder needs a little TLC but I expect to be doing the aforementioned back cutting next weekend. I'm curious to see how this helps my low lift flow. I'm no professional porter but I've gained some good flow so far. Thanks again. PAUL

The 452 intake port approaches the seat at a lower angle as compared to a 906 casting. I usually use back cut angles between 27 and 30 degrees on a 452 intake valve. Unless you have a way to see what your port likes, I would stick with a 30 degree back cut. If the 30 degree back cut gets to wide, sometimes I will narrow it with a second back cut angle. I do not use any back cuts on the exhaust valves.

Jim

Thanks I'll consider the second backcut. When you say "see what the port likes" are referring to flow or velocity ? I have a Superflow 110 bench so flow is all I can check. Thanks for the info I knew I came to the right place. MOPAR OR NO CAR !!!

67 heads stock valves, I cut the little ramp before the seat to match the slope from there to the stem. Not sure of how much hp gain but It really woke up that 383. Best et with street Hemi conv. was 11.61- 117 in my duster on a ten inch tire.