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MG MGB Technical - Head Conversion for Unleaded

I am sure this is a constantly asked question, but mine has a spin I have yet to find an answer for. They gentleman I bought my car from had said he ran the car (assumably putting in unleaded fuel, and doubtfully adding a lead additive) and he told me (with no receipt proof) that the heads had been converted to run unleaded. My question is, is there a way to go in and check to make sure the stellite valves and new valve seats have actually been put in the head (i.e. any way to visually inspect the head for the unleaded upgrades)?
D. T. Barnes

I had the head on a '67 B built with no-lead valves and seats. I could not tell much difference in the parts from original.
So, my guess would be no, and even if you removed the head you probably will only be able to verify new parts are there.

Dave
David Steverson

The only way to tell without removing the head is to use a borescope, either down through the spark plug hole, or in through the exhaust ports.

Even then, it can be difficult to tell the difference between original machining marks and inserts. If there is carbon build up, you may not be able to tell at all.

So what to do now - Run on unleaded with an additive, and don't worry, or run without an additive and check the exhaust valve clearances every 6 months or so, and unless the clearance reduces, don't worry.

Cheers
Ian F



Ian Fraser

Ian - thanks for the info on that one. I was prepare to pull off the head (I have a new set of gaskets for the engine). So I am going to give the engine a quick once over to make sure everything is mechanically sound and also get the gaskets all replaced, one less thing to have to worry about.
D. T. Barnes

D.T. There is a LOT of you should do this or do that out there, with this no lead mess! I have worked on & DRIVEN M.G.s for 37 years & will not have anything else!!!!! I have a 71 B motor in my 74G.T. & I torque the head every 10k & adj. the valves hot .013 intake & .015 on cyl. 1 & 4 & .016-.017 on cyl.#2&3 (exhaust valves are together & more heat & wear). I will ck. the valves wear befor I torque 10k later & I have .013 on the intake & the exhaust are from .013 to .015. I was totd to do this a long time ago by the oldtimmer & I have done it this way for 30 years & it has been a real long time for me to have to do a head change on the cars I work on. The brits put in some nickel in there cast iron & this made the head a lot harder than U.S. iron. I was at a head repair shop 30 years ago & we were facing the B valves & the man there could not beleave how hard the stock B valves were, he said the U.S. valves were butter to the B valves! I have stock B motors with 150k on them with no head problems. If your motors runs good, torque the head & adj. the valves & DRIVE!!!!!! I am overhear in De. come by &ck. it all out.
Glenn Towery

Hi guys,

Good to hear that the Brits got something else right! One theory with regard to lead in fuel is that the lead gets 'hammered' into the faces of the valves and the valve seats. This 'hammered-in' lead gives a 'memory-effect' which continues to protect the faces concerned after lead has been removed from the fuel.

It also seems that valve seat recession is minimal with engine speeds below a sustained 3,000 rpm - not to say that 3,000+ rpm isn't fun on occasion but that sort of engine speed isn't used all day, every day.

I agree completely with Glenn; run the car how you wish with the ignition set to run best with your chosen fuel. Check the valve clearances and when they start to close up seriously then consider upgrading the head. However, if the head has to come off for other reasons that, then, becomes an opportunity to fit hardened valve seats. But you may never have to!

FWIW

Peter
P L Hills

Glenn - thanks for the info, I will give the valves a checkout and see where they sit. Will have to come see you once I get my G back on the road, used to live in MD and spent many weekends in DE.

Peter - Thanks for the advice, and that was even the advice I got from some vintage car guys around here that run vintage US and Italian cars...

I think I am going to run her and about every 8-10K give the valves a check/tightening and play it by ear from there. Thanks all, any other advice is always welcome.
D. T. Barnes

This thread was discussed between 15/05/2006 and 17/05/2006

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