Unleaded valve seats

[monty]

Hi All,

Despite a couple of weeks detective work I have been unable to ascertain 100% if the head on my recent purchase has unleaded valve seats fitted. It should have, after work & cost by previous owner, but we are not absolutely sure. I am therefore putting in the suitable fuel additive 'just in case'! Would this do any harm if the seats have been modified or just overkill? Best to cover every option are my thoughts but comments would be appreciated as usual.

Cheers,

Monty.

[Fireman049]

Hi Monty ~

 

No, you won't do any harm using an additive. You can easily see if valve inserts have been fitted the next time

you have the head off.

 

Tom.

[Motorsport Mickey]

As Tom says.

 

Mick Richards

[RogerH]

Hi Monty,

if you have access to a reverse facing boroscope (120') you could stick it through the spark plug hole and see the valve seat area.

 

You probably haven't got access. Have you got a small airfield near you. These people use NDT (Non-Destructive Testing) who often use Boroscopes.

 

Where abouts are you on planet Earth - UK etc.

 

Roger

[monty]

Hello Roger,

I am in Gloucestershire.

What does one look for when looking @ valves seats?

Cheers,

Monty.

[graeme]

Hi Monty,

 

Below is a picture of a valve seat insert in a six cylinder engine. It should only be on the exhaust and a four pot should look similar.

 

Graeme

 

[Lebro]

1st time I have heard that the hard seats are only fitted for the exhaust valves, is this normal ?

 

Bob.

[RogerH]

Hi Bob,

yes, the seat needs only to be on the exhaust.

Essentially cool air rushes in over the inlet seat and keeps the temp down(ish).

However the exhaust seat has the full force of the high temp and air velocity rushing over it and it will get hot.

 

if you use leaded fuel the seat will get a coating of lead on it and be replaced continually.

With no lead in the fuel you will have a steel/steel interface. The softness of the head material and the impacting of the valve and seat will cause galling and eventually the seat will wear away (it could take a long long time). The hardened seat stops the galling effect.

 

Roger

[monty]

Hi Monty,

if you have access to a reverse facing boroscope (120') you could stick it through the spark plug hole and see the valve seat area.

 

You probably haven't got access. Have you got a small airfield near you. These people use NDT (Non-Destructive Testing) who often use Boroscopes.

 

Where abouts are you on planet Earth - UK etc.

 

Roger

Just a thought Roger. Won't the valves etc be covered in a carbon 'dusting' making it difficult to see things?

Cheers,

Monty.

[RogerH]

Very possibly - but worth a look if possible.

 

Roger

[Motorsport Mickey]

If the engine has done more than a thousand miles and especially if local work seeing that the engine has inserts through the carbon and **** build up might be a challenge, (as per Graemes post you can see how the machining lines on the insert could disappear under a coating) but no lookee no see anyway.

 

Mick Richards