Here's a post from May on the same subject. I saved it for future
reference. It still leaves your course of action unclear, though... grind
it down, weld up a staggered washer, fit shims, or find the other type of
manifold?
>Paul -
>
>Here's your May Day MG trivia. ' Ran across this several years ago when I
>converted my '76 to HS4s, the choice (over HIFs) being made on the basis of
>what manifolds I had in the barn. ' Just rechecked a catalog: 12H 709 was
>used through 1971 (HS4 equipped MGBs). 12H 3911 was used 1972-1974 (HIF
>equipped MGBs).
>
>Allen
>
>From: wizardz@maxinter.net
>>
>>Hi all....
>>Hey Lawrie... I pose this question to you more than the rest of the list
since
>>I assuming you have ... at least... seen a greater variety of exhaust
>>manifolds for different vehicles.
>>
>>I just this morning noticed a variance in the two exhaust manifolds I have
>>sitting about. Specifically I've noticed a difference in the thickness of
>>the mount flanges. Both are the stock type 3-to-2 cast iron.
>>
>>One unit says 'MOWOG' on the rear down tube with '12H709' on the front tube
>>this unit has a flange thickness of roughly 0.56"
>>
>>The other unit says 'AGA E1' (where the other said MOWOG) and it's forward
>>tube says '12H 3911' This one's flange is only 0.43" thick...<<snip>>...
>>
>>Paul Tegler
>>Twin 73' MGB GTs YB and OB
>>YB born 8/72 (Primrose Yellow) Yellow BGT
>>OB born 1/73 (Blaze Red) Orange BGT
>>North of Annapolis, South of Baltimore
>>email: wizardz@maxinter.net
>>http://www.amdyne.net/~ptegler/mgmain.htm
>>
>
>******************************************
>* Allen H. Bachelder =iii=< *
>* Sinking Creek Home for Wayward MGs *
>* New Castle, VA 24127 *
>* USA *
>* 540/544-7333 *
>******************************************
Bill Saidel had this to say:
>I'm replacing a Zenith-S with a pair of SU's and that requires replacing both
>intake and exhaust manifolds.
>
>So I remove the old stuff, put on the appropriate manifold gasket, slipped
>the
>intake manifold on the studs and positioned the exhaust manifold at the right
>position only to find the thicknessess of the two manifolds where the Fixing
>Washer (p.12, left side #16, Moss Catalog) differ. (Neither manifold was
>purchased new...) The exhaust manifold is significantly thicker. That means
>either grind down the 'flat' positions on the exhaust manifold where the
>washers sit
>so the washers sit flat or build up the intake manifold.
>
>Two questions:
>Anybody encounter this problem and what was your solution?
>Which of my two solutions is the better or the easier?
>
>If the solution is to build up the intake manifold 'flat' indentation for
>the washer, what material should
>be used for shims?
>
>TIA,
>
>Bill
>76B
>
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