Just purchased an Mgb GT after running a midget for five years which was non converted to run on unleaded so use an additive. I don't know if the B has been converted or not, any way I can tell?
Derek
leaded / unleaded head
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derek boghurst
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John Watson
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Re: leaded / unleaded head
Hi Derek
I am sure someone will know how to recognise a unleaded head, but not me.
Although I have an unleaded head fitted, I run my MGB on Tesco Momentum high octane fuel, it does help.
Enjoy your MGB GT
I am sure someone will know how to recognise a unleaded head, but not me.
Although I have an unleaded head fitted, I run my MGB on Tesco Momentum high octane fuel, it does help.
Enjoy your MGB GT
John Watson
1964 MGB Roadster Mk1
2018 MG ZS Exclusive 1ltr Auto
1964 MGB Roadster Mk1
2018 MG ZS Exclusive 1ltr Auto
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Peter Cresswell
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Re: leaded / unleaded head
Unfortunately, the only way to be sure that a head has been converted to run on unleaded fuel is to take the head off and examine it. This picture should help with your identification.
[attachment=0]Unleaded Head.jpg[/attachment]
Only the exhaust valve seat needs to be converted with hardened seats, unless the inlet valve seats have recessed badly and those have been done as well to recover the head.
At point A you will see a distinct machining mark, where the head has been cut to accept the new seat. If the head has been polished (as in a stage 2 head), this will be less distinct, but your should see a feint circle line of larger diameter around than the valve). It might need a bit of a clean up with a rotary wire brush (wear goggles) so you can see clearly.
At point B you can see the new insert in place down the valve throat. You can't see this unless you take the valve out, but the marks around the valve at point A will suffice.
Points C and D show an unconverted valve seat, in this case the inlet.
There is rumour that very late Marina 1.8 heads were unleaded, but I've not seen this substantiated so personally I doubt this, and in any case they are likely to be much rarer than an MGB head.
If you don't want to take the head off, then assume it is a leaded head and use an additive. I prefer Castrol Valvemaster to many of the others as you only need a small amount per fill up. Some you put in the whole bottle per fill up.
A final thought is that if only do a small mileage a year and/or don't use high rpm, an unconverted head seems to be fine for 10,000 - 15,000 miles without using an additive. You do need to check valve clearances more frequently, particularly if the engine seems to be running quieter (less tappet!), to check they are not closing up. This is a sign of valve regression where the valve is rapidly wearing the valve seat away.
[attachment=0]Unleaded Head.jpg[/attachment]
Only the exhaust valve seat needs to be converted with hardened seats, unless the inlet valve seats have recessed badly and those have been done as well to recover the head.
At point A you will see a distinct machining mark, where the head has been cut to accept the new seat. If the head has been polished (as in a stage 2 head), this will be less distinct, but your should see a feint circle line of larger diameter around than the valve). It might need a bit of a clean up with a rotary wire brush (wear goggles) so you can see clearly.
At point B you can see the new insert in place down the valve throat. You can't see this unless you take the valve out, but the marks around the valve at point A will suffice.
Points C and D show an unconverted valve seat, in this case the inlet.
There is rumour that very late Marina 1.8 heads were unleaded, but I've not seen this substantiated so personally I doubt this, and in any case they are likely to be much rarer than an MGB head.
If you don't want to take the head off, then assume it is a leaded head and use an additive. I prefer Castrol Valvemaster to many of the others as you only need a small amount per fill up. Some you put in the whole bottle per fill up.
A final thought is that if only do a small mileage a year and/or don't use high rpm, an unconverted head seems to be fine for 10,000 - 15,000 miles without using an additive. You do need to check valve clearances more frequently, particularly if the engine seems to be running quieter (less tappet!), to check they are not closing up. This is a sign of valve regression where the valve is rapidly wearing the valve seat away.
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- Unleaded Head.jpg (41.75 KiB) Viewed 10395 times
Pete
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
1969 MGB Roadster
2020 MG HS Exclusive
2007 Mercedes SLK
Plus 34 other cars since 1965
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derek boghurst
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Re: leaded / unleaded head
Hi,
Many thanks for your responses I have a very full history file which starts with the invoice for the car right upto the MOT last week so I spend evening and see if I can find an invoice. I also have a 1967 midget whch I know has not been converted because it had the additive in the boot but no bottle in the B and the dealer did not know.
Kind regards,
Derek.
Many thanks for your responses I have a very full history file which starts with the invoice for the car right upto the MOT last week so I spend evening and see if I can find an invoice. I also have a 1967 midget whch I know has not been converted because it had the additive in the boot but no bottle in the B and the dealer did not know.
Kind regards,
Derek.