Back cut your valves! always!

[ptownTSI]

valve jobs grind the valve seat which is in the head, this process involves cutting the edge of the valve to draw more air in at low intake & exhaust lifts to improve flow.

[LINUS]

i had a 3-angle done on my s50 head while getting the valve-job done, i didnt request is, isnt it pretty standard?

Yes - I've had 6 heads freshened up in life, and it seems like 3 - angle is a standard. I know one place that will do 5 - angle, but I've never bothered. Mostly because aside from 2 motor builds I've been doing them on the cheap.

Interesting article though - I'd never heard of cutting valves either.

[Jean]

i had a 3-angle done on my s50 head while getting the valve-job done, i didnt request is, isnt it pretty standard?

Same here.

[AndrewBird]

I assumed this was common knowledge...

[golde30]

i had a 3-angle done on my s50 head while getting the valve-job done, i didnt request is, isnt it pretty standard?

[Jordan]

Yeah, you are right. I didn't alter the valves at all.

[ptownTSI]

Indeed. My built M20 had 5 intake angles, and 6 exhaust angles. No doubt aided it in making the power it did.

That is on the cylinder head itself, its a multiple angle valve job, having the actual valve backcut is different and usually only involves one angle, say 30 or 32 degree's which is what is done on the domestic v8's.

[AlarmedBread]

Would anyone be so kind as to suggest some good angles for valves on an m20?

I'll be doing some head work soon and will definitely have some work done on the valves.

Any other machine work that should 'always' be done when rebuilding an m20?

[Jordan]

Indeed. My built M20 had 5 intake angles, and 6 exhaust angles. No doubt aided it in making the power it did.

[ptownTSI]

much cheaper to have a shop do it. you're in socal so you could go to their shop.

[z50_Jumper]

sweet, now all i need is everything to do the job. :)

[ptownTSI]

Very insightful article on carcraft.com for this month. they saw gains of up to 20% in flow from back cutting the valves. definitely a good read.

http://www.carcraft.com/techarticles/116_0612_valve_angle/index.html