I'm working on an 1150 head, and while its getting a valve job I was wondering if I should get the stock exhaust valves back cut and what is the best angle to have them cut? Also, would there be any benefit to back cutting the intakes? I'm using stainless APE intake valves and they seem to have a pretty flat back side already. I'm going to be running G-4 cams (.355 lift).
-
Required reading for all forum users!!!
Welcome!
Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.A note to new registrants...
All new forum registrations must be activated via email before you have full access to the forum.A Special Note about Email accounts!
DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.A note to old forum members...
I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.
Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...
-
Returning Visitors
If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.
If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.
Whats the best exhaust valve back cut angle?
- Thread starter TxGSrider
- Start date
S
sharpy
Guest
Best valve job is one from a real motorcycle expert. If u have it at some car "cylinder head specialist" run down there now and get it back
G
Guest
Guest
I cut my exhaust valves to 30 deg on the backcut. GS 1168. Valves came from Manley, one mm over on both intake and ex. Also had them nitrited and did some reforming of the faces. Port job with unshrouding around the valve seats. G3 cams.
headsbikesmopars
Forum Mentor
I use 36-37 degrees for Suzuki's I have tried 36 but 37 works better for me and my customers. While Kawasaki's seem to respond better at 35 degrees. I have found that hemi chambers 'like' 35-37 and wedge heads (auto) like 30 degrees. That is what my flow bench says anyway. I remember John Pearson telling me he likes 37 on Suzuki's also. I know backcutting does help low lift flow it uncovers more valve area sooner in the lift cycle. You can have the same flow @ .100 that you had @.150, same @ .150 as you had @ .200 and so on until around .350 or so at this point the valve is far enough off the seat to not affect the flow. I also believe it does benefit the exhaust side as well for same reasons. Back to back testing on flow bench shows this . Getting the 'moving' column of air moving sooner in the lift cycle helps produce torque sooner in the rpm scale (low end). JMHO.
Terry
Terry
Similar threads
