Counterboring Cylinder Head Valve Seats

[Natfunk71]

Is it practical to counterbore cast iron or hardened steel cylinder head valve seats with a mini mill? If not, what would be the least expensive new or used machine that could handle 16 valve seats per week on a routine basis? Exhaust 1.757" x .315" Intake 2.068" x .315"


The cutter heads look like this:



A tool holder rides on a snug-fitting guide that locks into the valve guide stem.

This is the cutter driver/holder:


This is the guide:

 

[matthewsx]

Assume you’re talking about cutting the valve faces to match new or reground valves?

16 per week is quite a bit but I used a Neway setup for racing kart engines and it worked great for this.

Valve Seat Cutters - NEWAY

Not sure I’d want to do it with a powered tool since they cut pretty quick and fitting new valve seats is a PITA.

John

 

[tq60]

Way back in the day, we used a very simple tool that was operated by hand.

A guide went in place of the valve stem.

A mandrel operated on that guide.

A hand held drill motor turned it.

Common shop item when folks fixed things.

We made some very unique valve to seat fits for the lawn mower once.

Sent from my SM-G781V using Tapatalk

 

[Natfunk71]

Assume you’re talking about cutting the valve faces to match new or reground valves?

Not to cut valve faces. I am using the Neway setup you've suggested to complete that task.

If cutting the seat will result in the valve being sunk too far into the head I need to install a new valve seat.

Also, if the existing valve seat is cast into the head I will need to install new hardened valve seats on the exhaust valves due to the unleaded modern fuel.

 

[Natfunk71]

The new seat is bashed in with a driver and a BFH. Then you cut the 3 angles.

 

[Bone Head]

View attachment 487160
The new seat is bashed in with a driver and a BFH. Then you cut the 3 angles.
View attachment 487161

Sportster heads or maybe shovel? That really doesn't matter. To use a cutter first make sure the guides haven't gone over sized or egg-shaped.
About the big f'n hammer...no. Run a bead of weld around the existing seat you want to replace. Seat should about fall out.
Bore the head to .002" (if memory serves) smaller than the O.D. of the new seat. Put the new seat in a freezer overnight. next day heat the head in your oven to about 200-250 degrees F. Valve seat goes straight from the freezer to the head as it comes out of the oven. use the seat driver and a 16-20 oz. hammer to drive it home. You'll do well after it cools to go around the outside of the new seat and use a punch to "expand" the head material for extra grip.
I prayed after I replaced the seats in my panhead. 50,000 miles on them and still looked ok when I pulled them for a re-ring.

 

[Nutfarmer]

You already have the critical parts. I would drive it with a slow hand held drill, 1/2 inch minimum. Trying to set it up in a mill would be difficult. The pilot is what is to align the cutter to the valve guide. Doing it by hand will allow the pilot to do its job. Even cutting new pockets for a new valve seat is easy by hand.

 

[Natfunk71]

Sportster heads or maybe shovel?

They are Shovel in the second image. I just grabbed them off Google.

 

[RaisedByWolves]

Is it practical to counterbore cast iron or hardened steel cylinder head valve seats with a mini mill? If not, what would be the least expensive new or used machine that could handle 16 valve seats per week on a routine basis? Exhaust 1.757" x .315" Intake 2.068" x .315"

View attachment 487155View attachment 487156
The cutter heads look like this:

View attachment 487157

A tool holder rides on a snug-fitting guide that locks into the valve guide stem.

This is the cutter driver/holder:
View attachment 487159

This is the guide:
View attachment 487158

Not really something I would do with the mini mill.

 

[matthewsx]

Not to cut valve faces. I am using the Neway setup you've suggested to complete that task.

If cutting the seat will result in the valve being sunk too far into the head I need to install a new valve seat.

Also, if the existing valve seat is cast into the head I will need to install new hardened valve seats on the exhaust valves due to the unleaded modern fuel.

I cut them with a small cutoff wheel and a Dremel, then a small wood chisel to remove.

If they are all the same I can see how something like a drill press with a custom jig would work. It’ll need to float somewhat to allow the guide to work so probably not too rigid of a fixture.

I suspect you’ll have to sharpen that cutter a lot with the numbers you’re talking about.

John