High Compression Head Spark Plug Info Needed

[got10carz]

Does anyone have knowledge about this head. I hope that the photos do the combustion chamber justice. The part # is A-1-2011. Also has A.C.

[Scott_Conger]

Neat
looks like a Ricardo combustion chamber
will be very interested in hearing what folks know about it

[Kerry]

Same combustion chamber as a Parker, but I don't know if he made his in cast iron.

[TRDxB2]

MAYBE? Discussion about making some heads
https://www.mtfca.com/discus/messages/1 ... 1315721998

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AC Foundry (permanently closed) Now Melling Engineered Aluminum Castings the same address
1146 North Raymond Road, Battle Creek, Ohio, 49014

[ThreePedalTapDancer]

That’s an A.C. accessory head. I’ve seen them on HIMICO engines.

https://www.mtfca.com/discus/messages/5 ... 1427066701

[TRDxB2]

That’s an A.C. accessory head. I’ve seen them on HIMICO engines.

https://www.mtfca.com/discus/messages/5 ... 1427066701

80253D19-F6A3-41A3-8EEC-0FE3CBE708AC.jpeg

Looks like Ed & I found different pictures & discussions for an A.C. Head. see image. While all 3 combustion chambers look alike the top of the Unknown head doesn't match that of the A.C. references. Doesn't mean it couldn't be an A.C. perhaps a different run or top design

[got10carz]

I'm convinced it's a AC. Above the valves is so deep you would need 1" lift before even thinking of checking for interference. Thanks for the quick ID.

[Allan]

The spark plugs on the Himico engine Ed posted are well and truly recessed, just like a Ford head. It is not like the initial post.

Allan from down under.

[Joe Bell]

I have ran this head for years on my Fordor, I like the combustion chamber and works really well for pulling hills in a heavy car, looks stock except no wells!

[speedytinc]

It would be good to know what the combustion chamber CC's to compare the displacement/compression ratio to other known heads.

I prefer a cast iron high compression head over aluminum heads with their corrosion issues. (Z)
We shall see how the Prus head holds up over time, but I have more confidence in the Prus head in this regard.

Neat head.

[got10carz]

I need suggestions for a spark plug in this head. I think I asked Joe, and he said A25 champion? What say you

[ModelTWoods]

I'm sure my thoughts are far from the truth, but AC could stand for Allis Chalmers and Allis Chalmers used T engines in early combines (harvesting machines), however, I would never expect a maker of farm equipment to make a high compression head for their use, although a high compression head was made for Fordson tractors. I'm not sure if it was made by Ford or Waukesha Ricardo.

[Mark Gregush]

The question might not be so much which sparkplugs but what gap. Not a whole lot of different heat ranges to work with when it comes to NPT plugs if that is what it uses. Or are they 7/8?
The other option might be to use adapters and experiment with different heat ranges and gaps.

[TXGOAT2]

If you run your engine within the normal T speed ranges at typical loading, standard heat range plugs should do fine.
If you have a stock ignition system, the plug gap probably needs to be standard or a little less.
An engine that runs at high speeds and loads might require a slightly cooler plug.
A high performance ignition system would allow for a wider plug gap.
An engine with a water pump might benefit from a slightly hotter plug.

The heads with no plug wells may require a long reach plug. Check the thickness of the head at the plug hole. The working end of the plug should be in the same place relative to the combustion chamber surface at the plug hole as with a stock head, or very close to it.
The plug electrodes should not be recessed into the spark plug hole when installed. Long reach NPT plugs were once available in great variety. Stationary engine hobbyists might be a source of information on them.

[Mark Chaffin]

Found another one.

[Craig Leach]

It may be my readers but those plug holes look like a fine strait thread & not a lot bigger than the head bolt holes? Has anyone tried to fit plugs
in the holes??
Craig.

[Mark Chaffin]

I'll sandblast it and report back.

[Allan]

Mark, your find is like the black one of Ed's. Note the recesses in the casting near the plug holes along the riser for the water outlet. There looks to be two different ones with similar combustion chambers.

Allan from down under.

[Joe Bell]

I came across another one of these a couple years ago and it took the Model A plug instead of the A-25 that my head took.

[Mark Chaffin]

Interesting that the valve pockets are so deep.

[TXGOAT2]

I'd guess the deep pockets over the valves are to allow better flow. The Z head has a lot of space in that area, far more than needed just to clear the valves. The later Ford V8s looked much tighter, and rodders would cut down the area between the valves and the cylinder bore to allow better flow, and probably did some relief on the head around the area over the valves. they did a lot of work on the ports, including the area just under the valves in the block. I believe that Ford V8s in the late 1940s had the block relieved at the factory. I had a 1946 ford with a relieved block, and I think it was stock. A problem with any flathead is getting good flow at high RPM AND high compression. In the 1920s, pre-ethyl, low octane gas limited how much compression you could get by with. A really well set-up engine could get fairly good volumetric efficiency in a certain speed range, and that would raise the actual compression realized. I believe that the dual plug heads were an attempt to address that by giving better flame front control to avoid detonation.

[Mark Chaffin]

[Mark Chaffin]

No cracks. No carbon in pockets. 1/2" NPT

[Joe Bell]

Mark, that is identical to mine!

[Mark Chaffin]

Yes. I believe it is one and the same. It was rusty when found with no carbon deposits. I believe it was never installed. Do you still have the patterns? It looks like it would work great with a very aggressive high lift camshaft with a little mill work.