| wilmalcolm | -- 11-15-2011 @ 2:05 PM |
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Hi, I have two sets of cast iron heads for my '36 LB engine. One is for flat topped and the other for domed topped. One head has much larger coolant passages from the block to the head. Since the 21 stud engines were known for their overheating problems, doesn't it make sense to use the ones with the larger ports? See image, Domed top at the top. Also note the different placement of the spark plugs in relation to head combustion chamber. Is that because of the shape of the pistons? This message was edited by wilmalcolm on 11-15-11 @ 5:05 PM
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| 40 Coupe | -- 11-18-2011 @ 5:20 AM |
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the part numbers for the two heads could carry a clue as to the difference? As you are probably aware the domed top pistons of the 36 require the domed top head.The 36 early factory aluminum domed top head (introduced mid to late 1935)48-6049/50 was was replaced late in 36 with 68-6049/50-A (aluminum) or -B (cast iron) around April of 36 the -A2 head was introduced and at that time the -A head became -A1 so the -A and -A1 are identical with large spark plug opening, the -A2 heads have small spark plug openings. Ford did try to overcome the over heating problems, with various fixes, but as we now know was more of a problem with casting sand and debris left or deposited, over time, in the rear of the block and the inability of the front mounted water pump to circulate enough water in this area. Fords fix toward the end of the flat head production was to enlarge the coolant holes in the rear of the head gasket and make the front holes smaller, restricting the flow in the front and increasing the flow in the rear. The larger coolant holes in the head will not do much to improve coolant flow unless the corresponding coolant holes in the block and the head gasket are of equal or larger size.
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| wilmalcolm | -- 11-19-2011 @ 9:52 AM |
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Thank you 40 Coupe for that informative answer. The lower head in the original post is the one that came off the engine and has no part number markings, only the inscription "Ford". The upper head is marked 68-6049-B. They are both cast iron. I inclose a shot showing the large water passages of the block which match the lower head image in the original post. The front and rear holes look to be the same size. So it looks like I will stick with the flat head pistons and the heads that were on the engine when I got it. The block is a LB block.
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