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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 Posted: Mar/21/2021 at 10:13pm
Your 15 years with the flat head engine is remarkable… Would surely like to hear more including any of the major work that was needed throughout the history of your Rambler American

What is this a 220?… & which body style?

 I am considering a 1965… Although the right machine 58 or newer would be acceptable

Nice write up… Should help a lot of us



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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/23/2021 at 6:08am
Design elements first appeared aroun 1935 in the Nash engine (actually, I think at least some of those elements appeared much earlier), but the 195.6 was a clean slate design for the 1941 Nash ambassador 600. So it was designed in the late 30s.

You should be able to shave 0.030" off the head and pick up about 0.25 compression, maybe a little more (maybe up to 0.50?? I don't think that much... big chamber area!). Any more and you're squeezing the transfer area too much. Should help a little with efficiency and low to mid rpm power, but doubt it will be enough to really notice. If the head needs to be trued up or is off for rebuilding the engine anyway, may as well go for it, but it's not worth pulling the head. These engines started off with 6.xx compression -- at 8:1 it's "high compression" for a flat-head.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Ken Doyle Quote  Post ReplyReply Direct Link To This Post Posted: Mar/23/2021 at 8:55am
Originally posted by 43n 43n wrote:

Your 15 years with the flat head engine is remarkable… Would surely like to hear more including any of the major work that was needed throughout the history of your Rambler American

What is this a 220?… & which body style?

 I am considering a 1965… Although the right machine 58 or newer would be acceptable

Nice write up… Should help a lot of us


It was a 1965 American 330 2-door sedan.  The only options it had were radio, heater, reclining bench seat, and automatic transmission.  The only thing I did a little different than the average owner might is that I ran premium fuel, and set the timing to the premium fuel spec in the owner's manual.  I drove it to work until the car was 48 years old, finally retiring it due to body rust from 48 years New Jersey winter road salt.  It had only clocked 120k miles, but the head was never off the engine, the trans was never out of the car, and it still ran great the day I retired it.  Once it warmed up, I ran it pretty hard.  It would use about 1 quart of oil between 4,000 oil changes.

I've also had two 195.6 OHV engines and ran one of them over 200k miles.  Of course I kept the head torqued on the OHV.  The two biggest differences between the OHV and the flathead are power, and weight.  The OHV 195.6 is pretty heavy for it's size.  My 1964 440 hardtop, with it's automatic and tall gearing, would run 85 MPH all day long.  My 1960 Rambler 6 4-door hardtop and my 1963 Classic 660 2-door sedan were very peppy for mid-size cars with such small sixes.

In both engines, I ran 10-30 oil in the winter, and HD30 oil in summer.  I always warm up my engines by driving gently, and after a hard run, always let them idle a bit before shutting them off, which oils the cylinder walls.

I've had about 8 Ramblers over the years, and got excellent service out of all of them.


Edited by Ken Doyle - Mar/23/2021 at 8:59am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Mar/23/2021 at 9:49am
The old economy models were just that. I still think back to the days when a large local Ford dealer did his TV ads. " Includes radio, heater AND white wall tires".
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Mar/23/2021 at 10:33pm
Originally posted by Ken Doyle Ken Doyle wrote:

 Once it warmed up, I ran it pretty hard.  [...]
I've also had two 195.6 OHV engines and ran one of them over 200k miles.  [...]
I've had about 8 Ramblers over the years, and got excellent service out of all of them.

Nice work. Maintenance and good practices do wonders. Most people don't have the patience, only us old car nuts even talk about it.


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/23/2021 at 11:16pm
Your experience is a testimony to the durability and longevity built into this engine and car. Plus of course your careful operation and maintenance.
This is great news ..I sure was hoping there were no replacement head gaskets or valve jobs needed… Nice work!
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/24/2021 at 5:07am
The Nash/Rambler/AMC flat-head is pretty bullet proof. No special maintenance needed. The only thing hard to do is adjust the valves. Supposed to be done every 8K or so, but most people just don't mess with them unless they start to make a noticeable amount of noise or they start to feel a power loss. They loosen slightly over time due to wear. They are just hard to get to with the motor in the car! If you ever pull the motor for any reason, ADJUST THE VALVES, even if the head never comes off. Do it while you can get to them easy! It takes a contortionist with the engine in the car from the top. Easiest way is to get it up on a lift so you can remove the steering linkage and K brace, but it's still tough. The OHV needs head bolt maintenance mainly due to the conversion nature of the design.

Other than adjusting valves in car, the only thing hard on the flat-head is taking that head off -- after it's been on for several decades. Some corrosion gets around the bolts in the holes. The first one I ever had to take off was due to a piece of lock washer falling down a spark plug hole. Landed on a piston and got embedded in the aluminum, knocked against the top of the chamber (got all the way to the tight part of the chamber). Sounded like someone inside with a hammer trying to get out! NOTE: blow/clean top of engine BEFORE pulling sparkers out!! I ended up using a steel wedge around the sides to get that thing off (over 100K, been on for 18 years... my first, a 61 back in 1979). I was concerned about damaging the sealing areas, but I worked it in a little at a time all around until it broke loose. Had to get it about 1/2" up before that happened! Luckily no damage. Head was shaved 0.020" just to true it up, block never pulled. It didn't need that much, machinist recommended it since it did need a small amount taken off (0.005-0.010... don't recall exactly). Today I'd soak those studs with PB Blaster or something for a couple days before trying to pull the head, and then I might try pulling the studs instead. Definitely use the starter with a good battery and the plugs in with all nuts off to see if that will break it loose first.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Posted: Mar/24/2021 at 10:15am
Thank you for the excellent write up… I have removed a lot of flat head cylinder heads and they can be tough… I think the worst one I ever read about was someone with a Packard straight eight... that is a lot of head bolts..or studs

Just to clarify… I like your idea of cranking the engine over and using compression to help lift the head… Or were you suggesting trying to run the engine with all the nuts removed… Guessing this would end up with a lot of coolant in your oil?

Oh.. first time trying an edit… What I should have said about the Packard Str eight cylinder head removal was that they lifted the head with a hoist using welded spark plug bolts ..I know my recollection is vague ...however I think they had actually lifted the front wheels off the ground and left it hanging overnight… Along with all the usual penetrants etc.


Edited by 43n - Mar/24/2021 at 10:37am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 43n Quote  Post ReplyReply Direct Link To This Post Posted: Mar/24/2021 at 9:18pm
Math is Done:

     Using your .045” ruler as equivalent to a compressed head gasket then from the block deck to the top of the combustion chamber is the .358” shown in your photo 

 ...Obviously the valves cannot lift that high or we are in trouble!

The cam lift is .340”.. Minus the valve lash .016” ..Gives us .324”
Valve lift

Subtracting ...we can now see there is .034” Clearance between  the fully open valve and the cylinder head roof

Assumptions: 1 that the valve upper corner is flush with the deck
                      2 That your cylinder head has not been milled

The exact numbers are not that important ..but the lesson is to check carefully if you decide to do any of the following:

     Mill the head
     Deck the top of the block
     Use a thin head gasket
     Decrease valve lash
     Install a high lift cam
     Over rev and float the valves

     … The way I drive nowadays the last one is irrelevant :-)
     
Good insurance is a lump of modeling clay on the head of both valves ..Next rotate the engine 2 full turns then dissect the clay for an exact measurement of valve to head clearance 

I did some more math that may be possibly useful but will post it later
Thanks Again for all the photos ..They are great!








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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Mar/25/2021 at 6:02am
Not running, just cranking over. I would expect the coolant to be drained if you're pulling the head. Doesn't have to be fully drained though.

You could actually start the engine -- just drain or pull the fan belt off first. It won't run, and that should definitely push the head up. No, it won't blow it up over the studs!

On second thought.... that might warp the head if some of the studs are really stuck and others loose. That's a remote possibility IMHO though... very remote. When it fires that part of the head will definitely come up and immediately lose compression, and cause a compression loss in 2-3 other cylinders, so only one, maybe two cylinders would actually fire.
Frank Swygert
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