Lapping valves/seats

[JuniorAtomic]

Hello guys,
I looked up the forum for lapping valves and there's plenty of info but I couldn't find a solid answer in regards to how to get both the valves and the seats lapped to the nice shiny condition.
What's the best/fastest way to do that on A4 block?
I got suction tools as well as grinding compounds but could get the heads sort of shiny but I don't like how the seats look like. In fact they haven't improved much.
Is there even a quick way to do the lapping on the seats?
Thanks,
Junior

[Dave Neptune]

Junior, yes the valves do get lapped on the seat for a good seal. However the seats if bad get re-cut with a "seat cutter" first and the valve get "ground round" by a valve grinding machine. After the cutting and grinding" which gets them real close to sealing the "lapping" finishes the seat and valve contact area for a good seal.

The seat cutter can often be rented from a parts house as it can be done on the block in the boat. The valves will need to be taken to a shop with the grinding equipment.

It is not a tough job, just be careful. Most of the seats in your pic look like they need to be re-cut.

Dave Neptune

[Al Schober]

Best bet for the valves is to take them to a shop with a valve grinder.
The seats in the block are tough unless you have the engine out. Goodson has tools to do the seats in place. https://goodson.com/
Last engine I did the block was out of the boat, so just took the valves and the block to the shop. The intake seats ground in nicely, but the shop installed carbide inserts for the exhaust seats. No extra charge. I also had the shop do the Kaminsky mod to the transmission casing.

[JuniorAtomic]

Junior, yes the valves do get lapped on the seat for a good seal. However the seats if bad get re-cut with a "seat cutter" first and the valve get "ground round" by a valve grinding machine. After the cutting and grinding" which gets them real close to sealing the "lapping" finishes the seat and valve contact area for a good seal.

The seat cutter can often be rented from a parts house as it can be done on the block in the boat. The valves will need to be taken to a shop with the grinding equipment.

It is not a tough job, just be careful. Most of the seats in your pic look like they need to be re-cut.

Dave Neptune

Thank you Dave. My block is out of the boat so I have room (but little time) to work on it unconstrained for space.
Noted on the seat cutter. Is there a way to grind the valves without taking them to the shop or it's a delicate process and better give it to professionals?

[JuniorAtomic]

Best bet for the valves is to take them to a shop with a valve grinder.
The seats in the block are tough unless you have the engine out. Goodson has tools to do the seats in place. https://goodson.com/
Last engine I did the block was out of the boat, so just took the valves and the block to the shop. The intake seats ground in nicely, but the shop installed carbide inserts for the exhaust seats. No extra charge. I also had the shop do the Kaminsky mod to the transmission casing.

Thank you for your reply. Even with my engine being out, the studs are still in the block so lapping/grinding seats is not the most pleasant endeavor as I learned

[JuniorAtomic]

I still yet to find a rental place in my town to get the seat cutter so instead I watched few Youtube videos at work on the subject and found what looked like a quicker alternative which tempted me to try it The guy was gluing few strips of fine sanding paper around the valve circumference and then grinding the seat with it.
I did the same and at first I liked what I was observing as the circumference became shinier and nicer. Then it hit me that grinding the seats with the little sandpaper strips was kind of making the "touching" angle of valve to the seat little round that what it probably should be. Attached picture is not very accurate due to shades and reflections but illustrates the result.
It seems that this proper angle should be 45 degrees and I'm wondering how critical is this for good compression and operation of the valves? Will certain variation of that angles work? Should I stop being a smart ass and just get the actual seat cutter to do it the right way?
Please share your thoughts.
Thanks,
Junior

[Dave Neptune]

In the past I had no trouble finding tools to rent from parts houses, you may try that. OR you could try to find a mechanic to "cut the seats" for you and you do the rest to save money. It is a rather straight forward process that does not take long at all. Of prime importance is access. You may be willing to contort to get in and do it but the mechanic may not.

The lapping process is just to seat any "minor" imperfection between the seat and the valve, this process only removes a few thousandths of an inch as the valve and the seat were done by two separate operations.

Good luck.

Dave Neptune