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Thread: M151 engine head differences?

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    Corporal
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    Default M151 engine head differences?

    Hello everyone I trying to find some information as to the key characteristics between the Light duty and Heavy duty engine heads the the M151s. I was advised that I have an early head and if it requires too much work then to replace with a Heavy duty head. I believe my A2 is an early AMG and the next question is when did the Heavy duty heads start being produced?

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    4 Star General nattieleather's Avatar
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    I am not aware that there was a light and heavy duty head. As far as I know the heads were the same on all M151s from start to end. I've used heads off of A1 motors on A2s and vice versa. Please if someone has more information please share but as I said I don't know of any difference of light duty vrs heavy duty.

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    Corporal
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    I’ve always heard that all a2 heads had heavier duty valve seats than a1 heads, but I don’t know for sure if that’s true

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    The heavy duty head was introduced as a retro fit to any 151 .
    as was mentioned they have hardened valve seats.
    The other improvement was a
    much larger boss that holds the exhaust manifold.
    typically an improved gasket is used to seal the exhaust manifold not just moly grease.

    Fil Bonica

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    4 Star General nattieleather's Avatar
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    I know that at one time a kit was available for the exhaust manifold which had four square gaskets made out of a fiber metal material, new clamps and bolts and this kit solved exhaust leaks at the manifold, but how knows if any still are available today.

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