50 degree valve seats & TPI motors

NewbVetteGuy

Well-Known Member
Grumpy et al,

I'd love to get your take on potentially switching to 50 degree valve seats at rebuild time, including for hot street or street/strip motors. Especially interested in the potential benefits for TPI and other long-runner, "2nd wave" intakes.

Many modern "hot street" motors are already using fast ramp roller cams that will lift the valves quickly off the seat to get into "good air" quickly. Many of these "inspired by LS" old SBCs are using things like beehive springs and lightweight, smaller retainers, and steel valves that should all help 50 degree seats to live on the street, particular at normal "streetable" RPM ranges (peak HP up to 6,500) -all these items should help with seat life, which has long been touted as the primary reason to NOT use 50 degree seats.

The 50 degree seats help a cam "act smaller" by hurting the low lift flow and acting as an anti-reversion dam. This allows bigger cams to be used or tighter lobe centers and we know from Vizard that max power in SBCs are achieved with much tighter lobe centers that people typically buy.

The 50 degree seats allow more flow at high lifts at faster average speed through the ports. The 50 degree seats also supposedly increase the strength of induction and exhaust wave tuning.


50 degree seats have been relegated to "race motors" but much of the benefits seem far more relevant to modern hot street builds (assumption: fast ramp, high lift roller cams and light weight valve trains are used).


Two articles / builds that show that the benefits of 50 degree angles kick in far before the oft-believed 0.25:1 Lift to Diameter Ratio:
https://www.hotrod.com/articles/1203phr-rethinking-the-valve-job/

2017 Engine Master's winning engine:
https://www.hotrod.com/articles/get-570-hp-small-block-350-chevy-pump-gas/
Note: 570 HP with 195cc intake ports
Note: You'd obviously never run this exact engine anywhere for any length of time as a flat tappet cammed motor with 1.8/1.85 ratio rockers, but that valve motion is EASY for a hydraulic roller with 1.6 rockers. The rest of the parts are pretty pedestrian- lightly ported Profiler 185cc heads, 50 degree valve job and valves, off-the-shelf Doug Thorley Tri-Ys, lightly ported motown single plane intake.


Adam
 
its been my experience that a properly done valve job with 3-5 angles and its the port throat and valve guide area under the valve,

[

that is a huge factor in its potential flow, but remember the header scavenging and compression and cam timing all effect the potential results, while the article may promote the 50 Deg valve seat angle a change in cam timing port shape or exhaust scavenging or rocker ratio, various porting tech, piston too combustion chamber mods, heat reflective coating, merge collectors , would have a more noticeable effect on the engines power curve in my opinion.
theres a reason the early SBC 23 degree heads with similar valve size to the later 18 degree heads can,t keep up, and its not the valve seat angles, theres a reason the later vortec heads with similar port volume and valve size to the mildly ported corvette fuelie heads out flow those early heads that were designed in the 1960s , and its not the valve seat angles!
and the biggest reason the 50 degree valve seat angle is not commonly used is long term durability, valves wear and seats wear and as the valve sinks deeper into the heads combustion chamber flow is reduced , now on a race engine that will be dis-assembled every season that may not be a huge issue, but if you expect to get 50K-100K miles its something you'll want to think through.


vgd5.jpg

porting+valve_area.jpg

exhaustpressure.jpg

EXFLOWZ4.jpg

pistonposition2a.jpg


blending the valve seat into the port throat with a 3-5 degree multi angle valve job, and porting the bowl area and valve guides,will have far more effect on power than a couple degree change in valve seat angle
valveg1.jpg

valveg4.jpg
valveg3.jpg






valvest.png

valvest.png

read this related thread and sub linked info

if your looking to run a marginally hotter cam without the loss of quite
as much low rpm
drive-ability,
RHODES rapid bleed flat tappet hydraulic LIFTERS will do that, at low rpms the reduce effective duration about 3-5 degrees but by about 4000 rpm you get full duration,
as theres not enough time for the lifters to bleed down as the llobes lift the lifter against valve spring resistance.

http://garage.grumpysperformance.com/index.php?threads/rhodes-lifters.1552/#post-6067

http://garage.grumpysperformance.com/index.php?threads/valve-seat-angles-and-air-flow.8460/

http://garage.grumpysperformance.co...alves-and-polishing-combustion-chambers.2630/
 
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Grumpy et al,

I'd love to get your take on potentially switching to 50 degree valve seats at rebuild time, including for hot street or street/strip motors. Especially interested in the potential benefits for TPI and other long-runner, "2nd wave" intakes.

Many modern "hot street" motors are already using fast ramp roller cams that will lift the valves quickly off the seat to get into "good air" quickly. Many of these "inspired by LS" old SBCs are using things like beehive springs and lightweight, smaller retainers, and steel valves that should all help 50 degree seats to live on the street, particular at normal "streetable" RPM ranges (peak HP up to 6,500) -all these items should help with seat life, which has long been touted as the primary reason to NOT use 50 degree seats.

The 50 degree seats help a cam "act smaller" by hurting the low lift flow and acting as an anti-reversion dam. This allows bigger cams to be used or tighter lobe centers and we know from Vizard that max power in SBCs are achieved with much tighter lobe centers that people typically buy.

The 50 degree seats allow more flow at high lifts at faster average speed through the ports. The 50 degree seats also supposedly increase the strength of induction and exhaust wave tuning.


50 degree seats have been relegated to "race motors" but much of the benefits seem far more relevant to modern hot street builds (assumption: fast ramp, high lift roller cams and light weight valve trains are used).


Two articles / builds that show that the benefits of 50 degree angles kick in far before the oft-believed 0.25:1 Lift to Diameter Ratio:
https://www.hotrod.com/articles/1203phr-rethinking-the-valve-job/

2017 Engine Master's winning engine:
https://www.hotrod.com/articles/get-570-hp-small-block-350-chevy-pump-gas/
Note: 570 HP with 195cc intake ports
Note: You'd obviously never run this exact engine anywhere for any length of time as a flat tappet cammed motor with 1.8/1.85 ratio rockers, but that valve motion is EASY for a hydraulic roller with 1.6 rockers. The rest of the parts are pretty pedestrian- lightly ported Profiler 185cc heads, 50 degree valve job and valves, off-the-shelf Doug Thorley Tri-Ys, lightly ported motown single plane intake.


Adam
There are many ways look at engines and parameters.
50 -55 degree seat angles come from Pontiac V8 Nostalgia Super Stock Racing.
Back in the day no Porting allowed.
No cleanup work.
No polishing whatsoever.
Not even a gasket match allowed.
Only valvejob could be altered.

After reading and looking at your posted charts what is actually going on is the Exhaust port is weak inneficient.
E/I Ratios still no where near .75 - .80 to 1.

Very few stock iron heads and aftermarket heads fall into that Race engine catagory.

Only Pontiac 1970 RAIV 614 heads from Pontiac are perfect E/I ratio balanced in the Pontiac World.
All others need porting work.
Flow bench test proven results afterwards.
 
So using a 50 degree seat angles on the intake side you kill flow area and exhaust port appears bigger.
E/I ratio improves.
Made more torque & Hp.
 
I have been told by several Pontiac engine builders that 50-55 degree valvejobs do not last on the street.
500 miles or so.
In a Drag car that lasts a long time.
 
I came back.. i see Grumpy added.

I am with him.
Use 45 degree seat main angles in a Chevy.

Factory Pontiac iron 30 degree intake seat angle.
Exhaust 45 degree main angle.
I am a big fan of 3 angle valvejobs.
If you can squeeze in 4-5 angles even better.
 
https://johnmaherracing.com/tech-talk/3-angle-valve-job/

https://www.enginebuildermag.com/20...ts-what-you-need-to-know-to-go-with-the-flow/

https://www.hotrod.com/articles/1203phr-rethinking-the-valve-job/

The basics of a three angle valve job:

On the inlet valve, the lap marks should be placed on the outer edge of the 45° valve face. This takes full advantage of the diameter of the valve. When the lap marks sit inside the outer edge of the valve, the overhanging portion of the valve serves as an obstruction to flow. The top cut on the seat (usually 30 degrees), establishes the outer edge of the seat and helps turn flow into the combustion chamber. A 60 degree bottom cut sets the width of the 45°seat.

The 45° exhaust seat is deliberately kept inboard of the outer edge of the valve – otherwise hot exhaust gas will eventually erode the edge of the valve.

The diagram below shows the three angles: 30°, 45° and 60°:

valve_diam2.jpg

3 angle valve job

After the valves have been lapped, a backcut is placed on the back of the valve, close up to the inner edge of the 45° seating area. This further improves flow around the head of the valve:

backcut.jpg

30° backcut

Look at a stock replacement cylinder head and you’ll find they have a basic 45° angle cut on to the seat. Lap in the valves and inspect the valve face to see exactly where the seat is coming in contact with the valve face. Even on aftermarket heads that come out of the box with a three angle cut, when you lap in the valves you’ll see the angles haven’t been placed for optimum performance.

The graph below shows the results of a flow test I carried out on a brand new CNC 044 cylinder head (40mm inlet valve).
The red line shows ‘out of the box’ flow with the factory fresh 3 angle seat.
The blue line shows the improvement by recutting and repositioning the 45° cut to the outer edge of the valve. I also added a 30° backcut to the valve.

044_flowchart11.jpg

Comparing ‘out of the box’ valve job to JMR muti-angle valve job

At .500″ lift there’s a 15cfm increase in flow. Depending on the engine specification, that translates into a potential power gain of at least 15bhp.

If you’re curious as to what difference backcutting the valve makes, here’s another test. This time using a band new stock 1600 twin port head (35.5mm inlet valve).

040_flowchart1.jpg

35.5mm inlet valve flow test – before and after

Red line: straight out of the box with no mods
Green line: 3 angle valve job
Blue line: 3 angle valve job plus 30° backcut on the valve
Overall gain in flow @ .500″ lift: 14cfm

This illustrates how even the mildest of engine builds will benefit from the addition of a decent valve job. On a mild 1776cc engine build, this modification alone could account for an increase of 10bhp or more.

Most people associate increasing the flow of a cylinder head with having to enlarge the ports. However, if the percentage flow increase found by opening up a port is less than than the percentage by which you’ve increased the port’s cross sectional area, you’ve just decreased port velocity. With a valve job alone, you increase flow with no modification to the port. Therefore any flow gains comes hand in hand with an increase in port velocity. It’s a win-win.


Carbide multi-angle valve seat cutter

Although the term ‘3 angle valve job’ is the commonly used term, nowadays many machine shops use four, five or even more angles when cutting valve seats. My first piece of valve seat cutting equipment consisted of individual grinding stones – one used for each angle. Today I use preformed carbide cutters, where all the angles are cut in one operation. Cutters are available in a variety of configurations. The advantage of using a carbide cutter is absolute consistency from seat to seat, with all seats being cut to exactly the height. Many of the blades I use also feature radiused blends from the bottom cut into the port and also above the top cut, blending smoothly into the combustion chamber.

valvejob.jpg

Here’s one I prepared earlier: stock 040 head with multi-angle valvejob
 
For A Good Valve Job, It’s All A Matter Of Degrees
http://www.superchevy.com/how-to/89678-valve-angles/

" heat is moving from the valve to the guide and not from the guide to the valve ...."
thats one reason sodium filled valve stems are suggested to be used on air cooled and turbo race engines

2205p_rw_savvy02.jpg


yes that's a very valid point here, the valve stem, and valve seat, is where the heat from the exhaust valve is rapidly transferred to the cylinder heads, keep in mind the valve train is on a 720 degree repetitive cycle than the valves spend over 1/2 of that seated on the valve seats in the heads, allowing heat flow out of the valve heads and stems to transfer to the cylinder heads
2205p_rw_savvy04.jpg

Jeff Smith Nov 1, 2002
1/9
2/9
There’s much more to a valve job than machining a few angles. Back-cuts, seat widths placement, and dozens of other variables all contribute. Here, we’ve used a mild lapping compound to identify the seat position on this Federal-Mogul big-block intake valve. Many shops prefer to use machinists’ dye instead.

3/9
This is an exhaust valve used on the Trick Flow Specialties 190cc aluminum head. It employs a radius on the chamber side of the valve to improve flow into the port. Not all exhaust ports respond to this kind of valve treatment.

4/9
Ken Duttweiler uses his Serdi machine to create a multi-angle valve job. The machine cuts all three seat angles simultaneously to produce an extremely accurate and repeatable valve seat.

5/9
This tight view of an intake valve that has been lapped illustrates the width of the seat on the valve. Using a dial caliper, we measured a seat width of 0.060 inch, which is a generally accepted street-engine spec.

6/9
Combustion-chamber walls positioned away from the valves improves airflow. This Edelbrock Victor Jr. big-block chamber has also been CNC-milled.

7/9
Valve margins (arrow) may not seem important, but they contribute to improved airflow and durability. A typical intake-valve margin should be no less than 0.050 inch. Exhaust-valve margins should be wider—between 0.080 and 0.090 inch.

8/9
The stock exhaust valve in the middle is a typical OEM valve. The valve on the left is a Vortec piece that incorporates the 30-degree back cut. The valve on the right is a Manley stainless steel piece. We found a 15-cfm gain at 0.400-inch lift on a Vortec head with the 30-degree back cut on an exhaust valve, which is why the heads now come that way from the factory.

9/9
Manley was the first company to champion the Pro Flo shape that reduces the stem diameter in the bowl area. This reduced stem diameter can result in improved airflow and slightly reduced valve weight. Manley now offers this shape in the Street Flo, Pro Flo, and Race Flo series.



As with most things in life, it’s the details that make the difference. You might not think that a measly degree here or there could make more horsepower when it comes to a valve job, but there’s power in those angles.

Engines use valves to control airflow for both the intake and exhaust systems. While sealing cylinder pressure is also important, performance-engine builders know that proper angles employed on a valve job can have a tremendous effect on airflow. And we all know that airflow is the key to making power. Increase airflow past those seemingly insignificant valves and you’ll make more power. It’s that simple.

Seat Time

Since flow decreases anytime air is required to change direction, it makes sense to create the transition past the valves as seamless as possible. With that in mind, decades of race-engine builders have discovered that multi-angle valve jobs do the trick.

The actual valve-seat angle is generally 45 degrees. On the combustion-chamber side of the 45-degree seat is a top angle that is usually around 30 degrees. This top angle serves two purposes. First, it acts as a radius to transition air between the 45-degree seat and the combustion chamber. Second, the top cut is used to reduce the width of the 45-degree seat from the top. The bottom angle, usually around 60 degrees, is often called the throat angle, and it also has two functions. Its primary task is to transition air between the 45-degree seat angle and the port. The throat angle also reduces the width of the 45-degree seat angle from the bottom.

But there’s much more to this than just angles. The position and width of the 45-degree seat on the valve is also crucial. For the intake valve, most head specialists like to position the seat as high (toward the chamber) on the valve as possible. One way to check this is to use valve-lapping compound that etches a light gray mark on the valve to reveal where the 45-degree seat contacts it. Some engine builders prefer to use red machinists’ dye instead so the compound does not cut into the carefully placed angles. Most machine shops prefer to place the valve seat in the middle of the exhaust valve for durability reasons. A seat too close to the edge may cause a burned valve.

The seat width is also very important to flow. There are almost as many theories on seat width as there are head masters. Most of the machinists we spoke with prefer an intake-seat width of 0.040-0.060 inch. Narrower seats generally improve flow but are also less durable. Narrow seats work best on drag-race applications where the engine is freshened often. Harder seat materials (e.g., induction-hardened seats) allow you to run slightly narrower seat widths than in the past while retaining excellent durability. Since exhaust valves operate at extreme temperatures, they require a wider seat to conduct heat away from the valve through the seat. Most shops specify 0.060- to 0.080-inch seat width for the exhaust side.





The position of the valve seat in the head is also important. Each time the valve seat is machined, >> material is removed and the seat “sinks” into the head, moving deeper into the port. This tends to sharpen the short-side radius of the port, which reduces flow. Larger valves (or fresh seats) often improve flow because the larger diameter repositions the seat back toward the combustion-chamber side where a fresh valve job can take advantage of the gentler radius.

Valves

Valve seats constitute only half of the flow picture; the other half concerns valves. They all might look the same, but the many high-perf valves on the market are a testament to how much attention should be paid to improved flow and durability. Companies such as Ferrea, Federal-Mogul, Manley, Milodon, Rev, SI, and many others offer performance valves in several configurations. You can spend big bucks for upscale valves, but the market is full of excellent valves for the street that offer excellent flow and durability at a reasonable price.

The first thing the valve needs to be is straight, which includes the tip. Most shops won’t assume a new valve is straight and will touch up the valve face to ensure concentricity with the stem and machine the tip to ensure it is perpendicular.

Besides the 45-degree face, a valve must also have a margin as shown in the Intake sidebar. Intake valves should have a margin of about 0.050 inch, and the edge should be sharp where it transitions to the face of the valve. Exhaust valves are a different story. The margin for an exhaust valve should be larger to improve heat dissipation—generally around 0.080-0.100 inch. Because the flow path for an exhaust valve is the opposite of an intake valve’s, you will sometimes see a smooth radius on the chamber side to improve airflow into the port.

There’s plenty happening on the back side of the valve as well. One of the best and least expensive tricks you can apply to any valve is a 30-degree back cut on the inside of the 45-degree valve seat. This creates a smoother transition between the backside of the valve and the 45-degree face, and it usually results in measurable gains in low-lift flow. This can be applied to both intake and exhaust valves. Reduced-diameter valve stems such as Manley’s Street Flo or Race Flo valves often exhibit a slight flow increase depending upon the application. Several other companies including Milodon and SI also offer this style of valve.



you DO REALIZE you can,t just drop the valve train parts, from kits they sell,
into or on, those bare cast heads

and have the result work RIGHT???:rolleyes:


http://garage.grumpysperformance.com/index.php?threads/valve-seat-runout.15104/#post-86003

http://garage.grumpysperformance.co...u-buy-bare-or-assembled-heads.534/#post-81754

http://garage.grumpysperformance.com/index.php?threads/multi-angle-valve-job-related.3143/

http://garage.grumpysperformance.co...gree-valve-seats-tpi-motors.14662/#post-98674

http://garage.grumpysperformance.co...gree-valve-seats-tpi-motors.14662/#post-98674

http://garage.grumpysperformance.com/index.php?threads/ccing-my-heads.14187/#post-71989

http://garage.grumpysperformance.co...olishing-combustion-chambers.2630/#post-48319

http://garage.grumpysperformance.co...at-angles-and-air-flow.8460/page-2#post-33298

http://garage.grumpysperformance.com/index.php?threads/removing-valve-seals.4283/#post-11290

http://garage.grumpysperformance.com/index.php?threads/sellecting-cylinder-heads.796/

http://garage.grumpysperformance.co...and-setting-up-the-valve-train.181/#post-1397




Machine Tools

Few backyard hot rodders own their own valve-grinding equipment, so most of this information is geared toward knowing the right questions to ask your machine shop and investigating the kind of work they perform. Perhaps the most significant leap in valve-seat preparation has been the use of a dedicated cutter rather than stones. The Serdi was the first machine of this kind. It uses a hardened-steel cutter that machines all three angles in the seat simultaneously. Previously, a valve job was a time-consuming task that used stones to individually grind each valve angle. Most engine builders now consider cutters superior to grinding, but there’s still plenty of debate on that subject. Regardless of the machine, the key to any good valve job is having a high-quality valve guide that accurately locates the valve. This means new guides and minimal clearances to ensure that the valve does not move around relative to the seat.

This has been our entry-level overview of what goes into a high-performance valve job. There’s much more to this subject, but this should give you a solid grasp on the importance of a professional valve job. It’s attention to those little angles and details that make the difference between a lackluster engine and a real street stormer.
 
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read this thread and sub linked info very carefully
 
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