Three-angle valve job.

[Methuselah]

Has anyone done a before and after on a flow bench, before being any set of heads (describe yours) and after being that same set of heads with a three-angle valve job?

Cutting the seats like that costs maybe another $100? Does it improve flow in a measurable way that makes it worth it?
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[Methuselah]

Dudes...
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[sy2185]

keep reading...

<font size=-1>[ This Message was edited by: sy2185 on 2002-02-05 06:28 ]</font>

 

[JSM]

a 3 angle in theory will increase flow.

the idea is to blend the seat more into a radius, instead of a sharp corner...

wether you actually get more flow, depends on many other things... the weekest link in the chain will be the max flow...basically.

so if valve wasn't bottle neck before, wont' help....if valve was, well it just may help...

so how do you know what is the weakest..well...that is why porting is an art..

 

[just a 6]

Well sense i'm an older guy i can tell you that in the late 70's a car magazine put a mid 70's Chevy 350 on a engine dyno, (just a regular stock smoged 2 barrel 350) and dyno it before and after doing a 3-angle valve job. At that time they gained 15HP with a 3-angle valve job compare to stock 1-angle (45*), you can also back cut the valves so you have a 2 or 3-angle on the valves. You get a better flow if you can aliminate any edges in the heads or runners that can interupt your airflow, making the radius on your valves and seats smoother is one way to do it.
So i belive you will gain power with a 3-angle compare to stock 1-angle.
That's my final answer :smile:

On 2002-02-04 09:33, Methuselah wrote:
Has anyone done a before and after on a flow bench, before being any set of heads (describe yours) and after being that same set of heads with a three-angle valve job?

Cutting the seats like that costs maybe another $100? Does it improve flow in a measurable way that makes it worth it?

_________________
Swede///
Sy #2550 100K

<font size=-1>[ This Message was edited by: swede on 2002-02-04 21:07 ]</font>

 

[Methuselah]

Swedish Dude, that's the answer I was looking for...

Knowing that I can make up to 15 hp with the three-angle if tuned correctly enough motivation for me.

Thanks guys.
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[ALLTRAC]

This is too general a question and no answer is going to be definate.

The majority of people porting heads and doing vavle jobs are stupid people. The outcome of a 3+ angle valve job depends on who is doing it.

The most frequently used valve job that I have seen would have to be a 30-45-60(competition my a$$). This valve job is old and should be retired to the trash can, but you will still see many cylinder head machinists using it(why?)Because they are stupid).

You can get cutters in any angle you want. Depending on the head and intended usage of the head determines what angles will work best for you.

On most 23* chevy heads I have had the best results using a 37-45-58. This will increase the mid-lift flow(.300"-.500").

45* seats are usually for lower lifts in the .600" and below range. While 55* seats are for the higher lifts .600"+.

When you hear of 5,6,7 angle valve jobs this is when the angles cut on the valve are added to the angles cut on the seat. This in no way will hurt, crack or warp anything.

Example:

6 Angle valve job.

SEAT.....................Valve

Top........ 37*..........Face.....45*
Seat....... 45*..........Backut...30*
1st bottom. 58*
2nd bottom. 75*

The widths of the cuts are also very important. They should be in this range:

SEAT Intake Width

Top.........(.060"-.080")
Seat........(street).060") - (race).040")
1st bottom..(.090"-.100")
2nd bottom..(cut this until 1st bottom reacehes the 1st bottom reaches .090"-.100")

SEAT Exhaust Width

Top.........(same)
Seat........(street).070")(race).060")(turbo).080")

VALVE Intake

Face........(.060"-.070")
Backut......(.060"-.080")

VALVE Exhaust

Face........(.060"-.080")(depending on usage)
Backut......(no backcut unless face is wider than .120")

The power increase depends on the quality of the head and how much it is flowing. Also on how good or bad the head is. Vortec heads you might see a 15-20cfm increase on a fully ported set. While on some Lb4,L35 you might see an increase of 10cfm.

I would not recommend taking your head to anyone unless they are well known for being great head porters. Ask questions also.


Ryan

 

[smeagol]

Ryan, what's yer take on valve sizing for Vortec heads in Syty app?

Nice sig pics :wink:

 

[ALLTRAC]

Depends where you want to go.

1.94" or 2.02"

A full race port with 1.94's the valve is the limiting factor.(maxing around 265-275 plenty of material left)

A full race port with 2.02's the port is the limiting factor.(knocking on 300 and about to become a miner)

I am using 1.94's for the simple reason that with a turbo and the right combination it will be enough to hit 9's(if parts allow). And for street I like to have a little more material.

If I were class racing I would use the 2.02".

Ryan

 

[Methuselah]

On 2002-02-05 04:44, ALLTRAC wrote:
This is too general a question and no answer is going to be definate.

The question was very specific...I simply asked if there was flowbench evidence of a three-angle valve job noticably improving flow. I didnt ask what a three angle valve job was and why it helped, and the Swedish Chef answered me appropriately.

However, your discussion of variations in the cuts for different applications is pretty cool, and I'll be mulling over it for a while.

Thanks guys.
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[ALLTRAC]

The question was not specific enough.


Not every three angle valve job is the same.


This would be like me asking if anyone has made more power with a custom cam but not asking the specs.

Then ten people post their results and some say they picked up power and some lost. What will I be able to learn from this?

Ryan

 

[Methuselah]

On 2002-02-05 12:29, ALLTRAC wrote:
The question was not specific enough.

Not every three angle valve job is the same.

This would be like me asking if anyone has made more power with a custom cam but not asking the specs.

Then ten people post their results and some say they picked up power and some lost. What will I be able to learn from this?

Ryan

I would be able to learn that there is *some* cam that could get me more power. I would have verification that the *concept* of obtaining more horsepower from a cam change is a real one.

I wanted verification of the ideas behind a 3-angle valve job and that's what I got.

Im also happy that people like yourself contributed experience and working knowledge to the discussion as well. But...this was beyond the scope of the question.





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