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Unleaded fuel?

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beebopbogo

beebopbogo

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While I was Googling for head replacement tips, I came across quite a bit of leaded vs. unleaded fuel comments. Do stock MGB cylinder heads wear out much faster with the unleaded fuel? What's the problem, and is there a way to fix it?

I guess I'm asking about it too late, since I already bought a used one at a smashing deal, but before I put everything back together, it's worth getting that much more knowledge about my 'B... So gimme the dirt on gas (85-92 octane).

Thanks!
 
There have been several discussions here about leaded vs. unleaded. I believe I can summarize the most popular opinion: "Drive it 'til you can't, and then when you rebuild, if it gives you peace of mind, go with the hardened seats."

Mickey
 
or to ease your mind, use lead additive and follow the instructions. It makes me feel better to use it, so that makes it worthwhile to me.
 
I just had a case of unleaded fuelitis. Compression way down on one cylinder on my '71 B. On pulling the head off, I found one exhaust valve had receeded into the seat. It used up all the clearance and then some so it no longer sealed. The valve was still round and I might have been able to "cure" it just by readjusting the valves but it would have been temporary.As a quick fix I installed a spare '66 head that was available. It took about 12K miles for this problem to show up from when I rebuilt the engine. At 2K miles per year think I'll leave the permanent fix to the next owner. Bob
 
You show a '79 "B" on your profile. Those were designed for unleaded gas. The older "B"s were not but can be converted with the upgraded valve components.
You should run something higher grade than regular. I run regular plus but the higher octanes are better.
If you still have the smog equipment on yours, you shouldn't run any leaded fuel in it.
Bob
 
I was about to say just that but Bob beat me to it! He is absolutely correct, the '79 is one of the later cars that had cylinder heads designed to run on unleaded. Just put the highest octane in it and don't worry about it!
 
Uh oh. I just got an earlier head to replace the stock '79 head. It was only $109, so if it works I'll just run it into the ground with unleaded fuel while I save money for a newer, unleaded head. This "new" head was from a 1974 MGB, casting number 12H2923. So exactly what year changed to unleaded compatibility?
 
Mine is a '72 and was designed for unleaded fuel.
So the '74 is OK for unleaded. I'm not sure what year it started.
Bob
 
Around here, you can get a machine shop to put hardened seats in for about $150.. have them clean up the new head, before you put it on, and drive it forever.
 
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