15 replies to this topic

[NDT]

I'm building up two heads - one is an MG metro head which will be built up as a fairly mild tune.

The other is my turbo head which will eventually get built into another fairly mild engine - maybe 120bhp with turbo.

 

Neither have hardened seats at the moment.

I won't do many miles a year, so the cost of fuel additive isn't an issue.

Are hardened inserts really worth it?

[Spider]

You'll likely get a conflict of answers here, all wrong and all right !

 

My own advice here is generally if the head is on the car then it's probably not worth removing it just to fit seats (and noted you are building up engines here),but if the head is off, then have it done.

 

Valve Recession from lack of lead or hardened seats only occurs when the exhaust temps get over a certain point (circa 700⁰ is memory serves me), Generally, driving about town, you're not likely to get them up to these levels, but if you do Motorway Driving or other stints where you are cruising on 3000 RPM or higher for longer periods, then there is every chance that they will get up to these temps.

 

I'm no chemist, but what I'm told is that at these temps, at a molecular level, as the exhaust valve seats, molecules from the cast iron bond to the exhaust valve, then as the exhaust valve opens, it tears these away, however, as there hasn't been sufficient time for the bind to really take and the flowing exhaust gases slightly slightly cool the valve, these molecules are then blown down the exhaust port.

 

I know some will say it's a non-sense and that it doesn't occur. If that's been their experience, it's only likely because their exhaust temps don't get up high enough for this to occur. It's been enough of a concern for all manufacturers to fit them, including Rover.

 

Here's a file photo I have of a valve seat where it's clearly been occurring

 

 

Of course, you can use an additive and if you are happy to continue to do this, then go for it. I always convert mine as I know I'll forget and I don't want that stuff all over my hands when I'm on my way to seeing the girlfriend.

[dyshipfakta]

Depends I would say. Standard 12g240 that are relatively cheap and a new casting can be picked up easy go for it. Something rare 12g295 or something that’s already had a lot of time spent on it and is abit special perhaps not for risk of ruining the casting.

[cal844]

Get a late cam4810 head, you wont need unleaded seats then, just alter the compression ratio for your application

[Turbo Phil]

Get a late cam4810 head, you wont need unleaded seats then, just alter the compression ratio for your application

A 4810 is no good on a 1275 engine, the 4810 is a smallbore head casting.

On a turbo engine where exhaust temps are high it would be beneficial for longevity to fit hardened inserts. It’s not that expensive to have done and it saves faffing about with additives.

Phil.

[Bobbins]

If you don't do it and you fit the head .... how long before it starts to play on your mind that you wish you had!

[cal844]

Get a late cam4810 head, you wont need unleaded seats then, just alter the compression ratio for your application

A 4810 is no good on a 1275 engine, the 4810 is a smallbore head casting.

On a turbo engine where exhaust temps are high it would be beneficial for longevity to fit hardened inserts. It’s not that expensive to have done and it saves faffing about with additives.

Phil.

doh, my bad!

I do agree with fitting hardened seats, the cost of the job will pay itself in no time

[NDT]

thanks guys.

Feels like its a case of "do it once and do it right"

I'm intending to fit the MG head (maybe with a tiny bit of work) and run the car for a while at the ~80hp level. Then if (when) I feel the need for more power I will convert to turbo - either with the original MG turbo head or another MG head which I've increased the chamber size on.

[Ethel]

It's a no brainer if you're having work done on the head.

 

Lead/additives will build up on the seats so they'll be protected for quite a while even if you're running on neat unleaded - of course, that'd get removed along with the metal if the seats are recut.

[smurfomatic]

Any idea roughly what fitting hardened seats would cost? Wondering if it's worth it now that I'm not doing as many miles in the Marcos, or if I just keep using Valvemaster

[Turbo Phil]

Any idea roughly what fitting hardened seats would cost? Wondering if it's worth it now that I'm not doing as many miles in the Marcos, or if I just keep using Valvemaster

I charge £110.

Phil.

[Magneto]

I do it on all the heads when I remove them for an engine rebuild or valve job.....good peace of mind. Since we have such long stretches between cities, I like knowing they'll take hours of high speed running with no issues.

 

Had a friend do a 2500 mile trip each way to a Mini event in 100* temps, he had to adjust the valves at the end of each day's running, by the time he got home the seats were almost gone. New hardened seats and he's running fine again.

[steeley]

How can you tell if they have been done already

[Turbo Phil]

Go to 1.20 on this video, it’ll show you what you’re looking for.

https://youtu.be/m5uCGVTrhEM

Phil.

[Dusky]

With little miles a I wouldn't convert personally. Even more because I have to run with octane booster anyway. With your turbo application it might be handy too