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Flat head combustion chamber

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43n View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Topic: Flat head combustion chamber
    Posted: Mar/17/2021 at 10:50pm
I would like to see the combustion chamber shape on the 196 flathead engine. Although I downloaded the 1965 TSM I did not find a bottom view of the cylinder head
Showing the combustion chamber

     Maybe someone could post a photograph?

Is there a desirable amount to mill the head for a little boost in compression?


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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Mar/18/2021 at 5:41am
Be aware that when you mill a flathead you restrict the ability for the intake and exhaust charges to get from the combustion chamber to the valves.

In the mid 60's I had a Fenton aluminum head that was already supposed to have a 8.5 to 1 ratio,  I had it milled .030,  put it on,  it was slower.
Ended up taking  the head back off and relieving the block between the valves and cylinder,  which lost me some compression,  but allowed the engine to breathe . 
66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Posted: Mar/18/2021 at 1:00pm
Thank you!
    I had been thinking about the extra restriction caused by milling the head...And unique to the Nash /AMC flathead design the intake channel now is also reduced in volume

 Some flathead sites caution that the amount of flow lost above the valve is significant and often overlooked 

Did you happen to Check the cranking compression pressure before and after the .030” cut?

The manual says 130 psi is stock… Even though the OHV 196 gives 145 psi..That’s what I was hoping for

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Mar/18/2021 at 7:20pm
I don't remember,  that was 55 years ago.

But the stock compression ratio was 8 to 1,  and the Fenton head was 8.5 , then I squeezed that.

I had access to some old 50's speed mags that even gave advice on hot rod Nash 6 cylinders.  They recommended the .030 head cut.,  but that was for a stock 53- 55 head,  that might have been even lower compression than the 59 American my 196 was in.  
66 American SW, 66 American 2dr, 82 J10, 70 Hornet, Pound, Va.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/18/2021 at 8:37pm
Still need photos? I have a block and head handy. The block is outside (yard ornament) because it has six cracks, so it will have to wait til morning.

Flatheads are terrible designs. This does not stop me from wanting to build and drive one. I even have a supercharger ready to go; never mind breathing, use a belt-driven hammer to get air in there (and increase it's already awful cooling issues) (I have a plan for that too). If I could only find a non-ruined one. Hauling 600 lbs of sticky rust around and dissasembling and paying good money to clean and check is getting tedious.


1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
1968 American, 199ci, T14
AMC pages: http://www.sr-ix.com/AMC/

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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Posted: Mar/18/2021 at 10:10pm
Of course… Sometimes I can’t remember things that I did 55 minutes ago!

Flathead engine cylinder heads & transfer areas always fight the compromise between flow and compression.

The flow will give you horsepower… The higher compression will give you efficiency.… Which do we want?
..All depends on how we intend to use the engine.

Thought I should look at what’s been done in the past That is why I would like to sethe AMC cylinder head combustion chamber first
   .. And then investigate some of the newer shapes such as the junior dragster/Briggs & Stratton & clone engines

I did review your flathead supercharged plan… Certainly finding a suitable block would be a big step… like a NOS complete short block

Incidentally I found a lot more AMC cars on “Offer Up” as compared to Craigslist

Thanks



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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/19/2021 at 8:57pm
I'll take photos tomorrow and post. 


1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
1968 American, 199ci, T14
AMC pages: http://www.sr-ix.com/AMC/

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/20/2021 at 1:26pm
Head photos follow. I took some low-grade measurements; the location, then the caliper reading. The steel rule is .045" thick, you do the math.

So lovely, so terrible.















I did the other valve pocket, but it's the same, so no upload. I could have sworn I did the "combustion chamber" but I lost the photo; no matter it's pretty much equal to the valve pocket.










here's #5, unencumbered.









1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
1968 American, 199ci, T14
AMC pages: http://www.sr-ix.com/AMC/

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43n View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Posted: Mar/20/2021 at 1:57pm
WOW!  Thank you for the over-the-top effort in taking these photographs.…
To say I am in shock is an understatement ...really makes you wonder what they were thinking in this design??

Do you think this shape was typical all the way from 1941 through 65?… Hard to criticize especially if they spent many many dynamometer hours developing this

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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/20/2021 at 4:00pm
Here's the 1958 block that head was on. It's sad junk.




The undercut (cast) here is about .15".

See how terrible the valve shrouding is! It's terrible! OHV too.









1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
1968 American, 199ci, T14
AMC pages: http://www.sr-ix.com/AMC/

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