I checked some heads this weekend and one particular head that had just recently been machined had the following readings.

Did the chambers twice cause it looked like the head surface is un-even front to back, do not know if this is typical or if this was a screw-up when the machine work was done.

Cyl #1 54

Cyl #2 57

Cyl # 3 57/58ish

Cyl # 4 58

Cyl # 5 58/59ish

Cyl # 6 58/59ish

If this is not typical than is it safe to assume it just was not loaded properly into the surfacer?

I am going to assume that the overall 1cc difference is not going to make any sort of difference in a driver but should I be concerned?

Casting in head would make that small difference.

Richard

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Part of Tyrde-Browne Racing

with a set of calipers you can measure from the valve cover rail to the firing deck of the head to see if there is a run in the machining.
Check the spark plug side and manifold side towards the ends and in the middle, to gauge the overall width.

I would not worry a lot about 4cc's,, but if you do any valve de-shrouding, by being a just bit more aggressive on the small one you can get them all with in a cc or two. Use your tractor supply cc tool and drop 4 cc's of water in a teaspoon and you will see about how much material to remove across the combustion chamber.

Yes, I understand but I am wondering if that is typical for the slant heads. I measured two others that I have ( unmachined as far as I know ) and had very consistent readings across the head.

Excellent idea on the calipers, I will do so. I thought ( or was told by someone ) that there was a known measurement of the thickness ( top to bottom ) of these slant heads, that they were consistent with this known measurement but I cannot find that info.

I am not going to use the head that is inconsistent for my build, I am instead going to use the second head that reads at 60cc.

I am just curious why the readings are inconsistent.

Aside from small casting inconsistencies valve recession can make a difference between cylinder volumes either from use of unleaded fuel, high mileage, or if new rebuild, valve was machined too deep into head or seats were installed at inconsistent depths.

Like Dad truck said:
4 cc ain't much to make up if deshrouding intake valve.

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

That is fairly typical, yes. You can find many heads that are better than 4 cc spread, but that is not uncommon.

Lou

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Home of Slant6-powered fun machines since 1988

Quote: Aside from small casting inconsistencies valve recession can make a difference between cylinder volumes either from use of unleaded fuel, high mileage, or if new rebuild, valve was machined too deep into head or seats were installed at inconsistent depths............

I wish that I had thought of this cause it makes much more sense. Thanks for giving me something else to consider.

Not worried, just hoarding what I can learn from you guys.

Ok thanks Lou. Just so I feel better I am going to stick with a head that is consistent though.