351m or 400?.
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351m or 400?.
Is there anyway to tell the difference from just looking at 351m & 400 from the out side to tell it's a 400.
or would you need to pull the spark plug to check stroke.
And how much compression does flat top pistons give you in a 1978 bronco 400.
or would you need to pull the spark plug to check stroke.
And how much compression does flat top pistons give you in a 1978 bronco 400.
res0rli9- BBF CONTRIBUTOR
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Re: 351m or 400?.
res0rli9 wrote:Is there anyway to tell the difference from just looking at 351m & 400 from the out side to tell it's a 400.
or would you need to pull the spark plug to check stroke.
And how much compression does flat top pistons give you in a 1978 bronco 400.
They look identical from the outside ... same block, heads and manifold.
Mark Miller likes this post
Re: 351m or 400?.
Use the calculator.
http://www.wallaceracing.com/cr_test2.php
I come up with 9.58/1 with a 78cc head 3cc valve relief .030" in in the hole and a guessed at 4.1" head gasket volume. It goes up to 10.17/1 with a .000" deck with the same numbers.
I have heard that some 400's have a casting mark or maybe it was a stamping, somewhere on the front of the block that 351M's don't. I never seen it though myself but, it was from a reliable Ford source.
http://www.wallaceracing.com/cr_test2.php
I come up with 9.58/1 with a 78cc head 3cc valve relief .030" in in the hole and a guessed at 4.1" head gasket volume. It goes up to 10.17/1 with a .000" deck with the same numbers.
I have heard that some 400's have a casting mark or maybe it was a stamping, somewhere on the front of the block that 351M's don't. I never seen it though myself but, it was from a reliable Ford source.
supervel45- Posts : 4493
Join date : 2013-09-04
Compression height
Richard the problem with the 400 was that dam piston being .070 in the hole from the factory .If you could get a piston closer to the top it would run like a stroked cleveland .To the op just have a rod of some type pull a spark plug mark you r rod turn over the engine from top to bottom measure and it will be 3.5" or 4.00" I used to do that all the time checking 360-390s.Doug
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manofmerc- BBF CONTRIBUTOR
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Join date : 2011-03-31
Mark Miller likes this post
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