Valve angle (s)

[jeepguy1948]

When looking at replacement valve sets online I see that they are supplied with different angles for intake and exhaust. The motor That I took apart had both intake and exhaust at 45 degrees.

I’m going to be grinding the seats so I can change the angles if that is the thing to do.

Are “3 angle” valve seats a good thing on a flathead or not?

[Bored&Stroked]

Originally Posted by jeepguy1948

When looking at replacement valve sets online I see that they are supplied with different angles for intake and exhaust. The motor That I took apart had both intake and exhaust at 45 degrees.

I’m going to be grinding the seats so I can change the angles if that is the thing to do.

Are “3 angle” valve seats a good thing on a flathead or not?

Not exactly sure what you mean? The hardened valve "seats", the valve faces or both?

Three angle valve jobs are not specific to flatheads or any other engine. The reason you need multiple angles is that without having at least 3, you can't control the width of the seat and where it is located on the valve. These dimensions/locations are different for intake versus exhaust valves and the application (street or 100% competition will change what should be done). Also, multiple angles are used to improve flow out of the port and across the seat itself - with many ways and approaches to the work.

You would normally not need to put new hardened valve seats in unless yours were severely worn or you were putting larger valves in the engine. Or, if your engine was a later model --> certain 49-53 blocks where there were no hard seats, or maybe hard seats on only the intakes. All 32 - 48 blocks had hard seats for both the intake and exhaust valves.

Most performance shops will use a minimum of 3 angles on the seat to do three things:

1) First, the actual sealing area is ground first - typically 45 degrees. It will be wider than it needs to be
2) Then a top-cut is done to set the outside seat location where it needs to be in reference to the edge of the valve seat face (different for intakes vs exhausts). I've seen these angles from 15 to 30 degrees.
3) Then a lower-cut is done to set the final seat width and to blend the 45 degree seat into the bowl area. Typically, this is a 60-degree angle - or something close to that.

This is just the basics - some guys use different angles than others, some use more angles, etc, etc.. On some racing flatheads we use 30-degree seats on the intakes (and specially profiled valve heads). Lots of ways to skin the cat - but all of this work is done at the machine shop of choice.

When putting new sets in, they will need to be blended into the port and then the actual seats are ground in. Usually, we will put 3+ angles into the seat to help blend the seat into the top and bottom. But - all these angles are done AFTER the hard seats are installed. I've never used hard seats that had the angles pre-ground into them. Even if they did, they would need to be redone for the actual engine they are installed into as they would not be in the exact location to match the valve and guide for a particular block.

Question: How are you going to grind the seats? Do you have the special flathead-only pilots that pick up the lifter and guide bores? You shouldn't use just a valve guide and a 11/32 pilot - you need the right pilots to do the best quality job. It is getting harder and harder to find machine shops that have the right tools and know how to work on flatheads - so make your choices carefully!

[Pete]

Originally Posted by jeepguy1948

When looking at replacement valve sets online I see that they are supplied with different angles for intake and exhaust. The motor That I took apart had both intake and exhaust at 45 degrees.

I’m going to be grinding the seats so I can change the angles if that is the thing to do.

Are “3 angle” valve seats a good thing on a flathead or not?

Using 30 degree on both will gain you some flow but with no other mods, you may not notice in the seat of pants.

3 angle is definitely good for more flow.

Knocking the cobs and corners off the inside of the ports helps also.

[jeepguy1948]

Mr. Bored Sir, You are spot on that is exactly why I am exploring the possibility of doing it myself. Our Model A club owns a seat grinding set up (as well as a valve grinder) so the tools (maybe not that pilot) are available. The only shop I know of that can do flathead work in our area is backed up until November. I would have hardened seats installed but we can’t wait until November so lead substitute will have to do. Regarding the hardened seats, I assume that I would see them if they were there and I don’t see anything. The motor is an 8BA installed in a ‘51 F-1 but it is not the original engine so the motor might not be a 51. I’m going to see about date coding the block and go from there. The sad truth is that we who are into the old stuff are becoming more and more challenged and having to make compromises because all the old timers are either retired or dead and nobody is stepping up to get in that business. Covid alone killed off quite a few of those “old timers”. I will now step down off of my soapbox. All that said, I have never done a seat grind in 50 years and I don’t remember it too well now.

[Pete]

You do not need hard seats in any flathead Ford engine except to repair cracks or damage.

We used to run 100% nitroethane + hydrazine with no hard seats.

Besides all else, they inhibit heat transfer.

[jeepguy1948]

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Thanks Pete!

[Bored&Stroked]

Pete is the best! Listen to his wisdom . . . he has a bit of it.