Ford 302 Block Age

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jamesmacv8
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Re: Ford 302 Block Age

Post by jamesmacv8 »

Roger,

I have taken note of crank storage, seen that before somewhere! I'll be measuring the bores properly soon, so will let you know, but I fear that I require a bore to +30.

In the meantime, this may be a silly question, but what is the blind tapped hole for next to the casting number on the 289/302 block? see sample image:
hole.png
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Roger King
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Re: Ford 302 Block Age

Post by Roger King »

+0.030" is the standard first rebore size, you'll struggle to find pistons between std and plus 30. For some reason yank motors generally go std, +30, +40, +60. +60 is risky and I wouldn't do that on an engine I was going to spend any proper money on.
Don't know what that threaded boss is for - I don't remember ever seeing anything in one.
jamesmacv8
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Re: Ford 302 Block Age

Post by jamesmacv8 »

Roger,

I have measured the bores (3 positions for "out of round" and top(just under lip), middle, bottom for "taper"). Results below:

max. measured diameter = 4.0074" (No 3 cylinder)
max. taper = 0.0059" (No 5 cylinder)
max. out of round = 0.0035" (No 8 cylinder)

Not as bad as I thought, with respect to taper (up to 0.010" allowable) and out of round (0.005" allowable), however bore tolerance figures suggest 4.0004" to 4.0052" and I'm approx. 1.5 to 2.0 thou. over that on all bores (at the top only).

What are your thoughts, do I go to +0.030? Would be nice if I can just do a manual cross hatch hone myself perhaps?

James
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Roger King
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Re: Ford 302 Block Age

Post by Roger King »

It's your call really - what does your machine shop recommend? If it's over tolerance I'd play safe.
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