30 degree backcut on intake valves.....

sstocker31 · #1 10-19-2017, 06:36 PM

Has anyone tried a backcut on the intake valve to help promote low lift flow? Curious if it improved power at all....

Robert Anglin · #2 10-20-2017, 06:37 AM

We run the E.C.I. tapered cylinders and the "X" seats and guides. I do not know for sure but E.C.I. I think from 10-15 yeas ago said that the air flow was improved by, I don't recall exactly maybe 6%. We did all the hand cleaning and removed the casting seams and tailings, then textured the intakes and exhaust ports ( We don't polish anymore ). Out of the factory data for than engine it should have put out around 191 Hp., but after testing it and seeing fuel flower from 18.2-19.1 at full power runs we think it is a little higher than that.
You may be able to find Bobby Lopper down at the new location for E.C.I./Cont. and ask him about the specs for the best flow for the valve seats as they did all the lab testing for those units.
Hope this helps, Yours, R.E.A. III # 80888

TS Flightlines · #3 10-20-2017, 07:27 AM

3 angle 'valve jobs' have been in use for decades in race cars. When used with porting it does help, but you can over do it. In order for it to be optimum, all components need to be matched. Intake flow, piston head design, valve seats, exhaust port, exhaust, camshaft lobe lift and duration. All of this is performance race car stuff.

Check with Allan Barrett on all of this!
Tom