5 replies to this topic

[Noidear]

Does anyone have any advice, experience, or suggestions with Refreshing the valve seats DYI style?

I am currently looking to purchase a Neway valve seat tool kit. Before purchasing I do need to find the valve seat angles for both exh and inlet seat, if anyone is aware of them? I hope to only use one angle on the valve seat, because I do not see big advantages to 3 angle valve seat...?

Back Ground

I have replaced the valve guides for new ones and have found the new valves do not seat properly. They are close, but I believe them to be, beyond what hand Lapping with past can correct. The head is off an 1995 spi 1275.

Thank you

 

 

[Turbo Phil]

The valve seats should always be recut after replacing the guides. The valve seat angles are 45deg for both inlet and exhaust. You won’t be able to cut a 3 angle seat on the exhaust unless you go to a larger valve. On the inlet it’s possible if you back cut the valve to narrow the seat first, this then means you can use the excess seat width in the head to cut the other two angles.
There’s a substantial gain in airflow if you cut a 3 angle seat coupled with a valve back cut. The valve seat on its own gains nothing.

Phil.

Edited by Turbo Phil, 22 February 2022 - 10:05 PM.

[Noidear]

Thanks for all the info. Do you use very high end machines that cut your seats? Have you ever used one of the manual hand turned carbon cutters before?
Thanks again

 

 

[Spider]

If you have hardened exhaust seats fitted, the Neway will cut them, but oh so slow, like real real slow. Did I mention they'll cut the exhausts slow ? Yeah,,,, very slow.

Really, I feel the hardened exhaust seats, even for a touch up, let alone a re-cut after new guides, are beyond what the Neway can sensibly do. An inexpensive means of doing these for the guy at home is a Seat Grinder, like a Synchroseater.

[grizzler73]

I've looked into this also, I'm not convinced that the outlay for a Neway is worth it for the amount of times you do this operation, 

I ended up with the conclusion that it would be easier to get a machine shop to do it.

[Turbo Phil]

If you want something that will cut hardened seats easily I’d look for a Wolf/Black & Decker etc electric grinder which uses angled stones. These can be picked up for a similar or less price than the Neway cutters and are much faster to use.

Phil.