Heard this said in many magazine articles, about getting a three- or four-angle valve job. Actually, just skimming through the February issue of Honda Tuning and saw that a 5th Gen Hatch with a B18 had a 7 angle valve job...

My question is: what in the hell is a "#" Angle Valve Job? In what way is it modifying the valves, and where does the number of angles come into play.

Hey, noobie question, I know, but I'm just trying to be the Honda masters that the rest of you guys are!

Thanks in advance

 

from what I have heard (might be wrong) you cant really have more than a 3 angle valve job. A guy I work with at the shop told me this...

Confirm?

 

basically, a # angle valve job is done by resurfacing the seat where the valve sits when pulled against the cylinder head. the # refers to how many angles have been cut into the valve seat.

so lets say a 1 angle valve job... the edge of the valve has a 45 degree angle that sits on a 45 degree valve seat on the cylinder head.

a 3 angle valve job... the valve would still have a 45 degree angle, but the valve seat would be cut so that it has a 30 deg, 45 deg, and 60 deg angle making the valve seat more "rounder"

the purpose of this, so i've heard, is that grinding more angles causes the valve seat to "round out" and when the air is drawn into the engine, the angles create a venturi effect such as the one found in carbureators that speeds up the air intake.

i haven't heard of a 7 angle valve job, but honestly, you can cut as many angles as you have cutting stones.

 

the most would be a 5 angle valve job

 

7 angle valve job = 5 cuts on the valve seat + 2 extra cuts on the valve itself

 

i've heard that anything above a 3 angle job is useless, and may even hurt performance. i personally have no idea. can anyone clear this up?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MugenDude &raquo;</TD></TR><TR><TD CLASS="quote">i've heard that anything above a 3 angle job is useless, and may even hurt performance. i personally have no idea. can anyone clear this up?</TD></TR></TABLE>

i'm not entirely sure, but i would say that it's not true. being useless maybe because any more would probably be not noticeable.

if you take a square and cut off a piece of a corner on each corner, you'd get a octagon. cut more angles and you'd get more and more closer to a circle (which is basically infininte angles if you would consider them angles.). the more angles you put onto the valve seat, the closer you'd get to a circle, which gets a better venturi effect.

but it does get to a point where you can cut more angles and the performance increase will be neglegible.

 

there are many theories on valve seat geiomitry some engine builders use a 3 angle some use 5 and some use round out the seat then put a 45 on it nobody can prove what is the best but a 3 angle valve job is not a bad thing to do to a motor. some engine builders will say that a valve job can by as much of a difrence as a port and polish job because the valve is just opening and closing twice every time it opens so it spends more time near the seat so a valve job helps quite a bit

 

THE MOST COMMON PERFORMANCE VALVE JOB IS A THREE ANGLE 5 ANGLES COME INTO PLAY WHEN YOU ARE TALKING ABOUT V8'S OR ANY OTHER HEADS THAT UTILIZE BIG SEATS, THE ANGLE CAN MAKE OR BREAK POWER POTENTIAL.
THE 45 IS WHAT SEALS THE VALVE TO THE SEAT AND BY CUTTING THE 30 AND THE 70 ON EACH SIDE YOU CAN NARROW THE 45 TO A DESIRED WIDTH.. AND THE ANGLES ALSO DICTATE HOW THE FLOW WILL ENTER . IT CAN ALSO SHIFT YOUR POWER BAND...

 

whoa, a valve job can shift your powerband? does the power tend to come sooner the wilder the valve job is?

 

MOST COMON SHIFT IS SACRIFICING LOW END POWER FOR HIGH END.

 

a 3 angle valve job is stock on honda egnines, least it is for evey single one i worked on so far.

 

3 ANGLE CUTS DO COME ON FACTORY HONDAS AND THAT IS ONE REASON THEY FLOW SO WELL

 

So theyre best left untouched?

 

DEPENDS ON WHAT HEAD
THE S2000 HAS PROVEN TO BE VERY TRICKY ALONG WITH THE K20
BECAUSE RULE OF THUMB(WHICH IS NOT ALWAYS TRUE)IS THAT YOU WANT A NARROW 45 PUSHED OUT TO THE EDGE OF THE VALVE FOR GOOD PERFORMANCE. BUT ON THE F20C IT HAS A REALLY WIDE 45 AND THE RULE OF THUMB DOESNT WORK WELL ON THAT HEAD ..

AS FAR AS THE REST OF THE HONDA HEADS GO SOME ONE WHO KNOWS AND HAS ENOUGH EXPERIENCE CAN MAKE IT BETTER

 

What do you think abut getting an valve job on a B16a head? If its already OEM cut in three angles, does having a 3 angle valve job make any sense?

 

GIVING A PERFORMANCE VALVE JOB ON A B16A MAKES PLENTY OF SENSE!
IT IS PROBABLY ONE OF THE MOST COST EFFECTIVE WAYS TO INCREASE EFFICENCY.
A GOOD VALVE JOB CAN HELP ALL YOUR EXISTING BOLT ON PARTS WORK TO THEIR FULL POTENTIAL.. IF YOU NEED ANY HELP JUST LET ME KNOW

 

Turn off your caps button

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EG6R &raquo;</TD></TR><TR><TD CLASS="quote">What do you think abut getting an valve job on a B16a head? If its already OEM cut in three angles, does having a 3 angle valve job make any sense? </TD></TR></TABLE>

thats called getting a stock valve job actually....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v4lu3s &raquo;</TD></TR><TR><TD CLASS="quote">

thats called getting a stock valve job actually....</TD></TR></TABLE>

So does that mean it can't be done because it is already done? Or does it mean cutting 3 more angles in the valves?

 

Without googling for valve jobs I this is what I remember when I was doing research years ago on a turbo build up for a 280z datsun. You can do a continous radius (not sure if that is what it is called where the valve and seat basically are a continous curve and matched). Then you can do N number angles where you have some number of flat contact areas then an angle then another flat area. The width of each flat area supposedly affects flow and the ability to shed heat. Engines/heads have their own personality so there may be things that work well on one motor that don't work well on others. Only your dyno knows for sure (or actually track performance).

From the turbo search what I remember was the life of a valve job. A good 3 angle supposedly gave the best life for a street motor where a continuous angle gave the best performance had the shortest life.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Justin_Bradley &raquo;</TD></TR><TR><TD CLASS="quote">So does that mean it can't be done because it is already done? Or does it mean cutting 3 more angles in the valves?</TD></TR></TABLE>

it means unless your valve seats are messed up you dont need to pay for a new valve job that is identical to what the head already has.

 

well doing a valve job on a head can be good because it cleans up the seats

can u tell what one hasent been done yet?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by v4lu3s &raquo;</TD></TR><TR><TD CLASS="quote">

it means unless your valve seats are messed up you dont need to pay for a new valve job that is identical to what the head already has.</TD></TR></TABLE>

not neccessarily because there is a difference many different head shops have preffered cutters for example the factory valve job seats the 45 almost in the middle of the valve face and the 45 itself is pretty wide. now a performance valve job does still have 3 angles but the 45 can be manipulated to seat near the end of valve face and the 45 can be narrowed.. in short a performance valve job can help make more power.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FLOWZILLA &raquo;</TD></TR><TR><TD CLASS="quote">MOST COMON SHIFT IS SACRIFICING LOW END POWER FOR HIGH END.</TD></TR></TABLE>

Actually, multi-angle valve seats increase flow more at low lift and taper off at high lift resulting in more low RPM power and torque without sacrificing high RPM power.