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50's OHV "Big Six" specs

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    Posted: Apr/17/2012 at 8:47am
This question goes out to Farna or any other early six expert. I would like to know or be pointed to where the answer is on: bore spacing for the OHV 3.8 and 4.1 OHV  Nash sixes from the 50's, overall engine length or at least as compared to the modern 199, 232, 258, engine weight, and final, were there any crossflow heads from factory or aftermarket apart from racing or factory prototype one-offs? Thanks.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Apr/17/2012 at 10:34am
  Farna will probably come by later.
 
  The old Nash six 235 ci was 3.37 x 4.38 bore and stroke,  where the modern AMC 6 232 was 3.75 x3.50.
 
  The Nash 252 was 3.50 x 4.38,  while the AMC 258 is 3.75 x 3.90.
 
  While both the AMC 199-232-258-4.0 and the Nash big sixes are both 7 main bearing engines,  i'd doubt there'd be any commonality in moving parts or bore spacing or head interchange,  because of the radically different bore a stroke combinations.
 
  The Nash Healy had the Nash big six in it when it raced at LeMans in the 50's,  and they did make some twin carb heads,  and I've heard rumors ( rumors, now) of a experimental DOHC head for the Nash Healy .
  If you've ever looked at a 196 flathead and seen the straight pipe exhaust going down the side of the block,  the Nash big six used the same method for the exhaust on their ohv's.   Not something with a lot of performance potential,  stock.  But they did modify them to be fairly powerful for their day for the Nash Healy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slate Quote  Post ReplyReply Direct Link To This Post Posted: Apr/17/2012 at 5:03pm
I have certain ideas, and weight and length factor heavily in. I like the later sixes but for my gameplan they are too long. Weight can be mitigated ( alloy head, custom exhaust, etc.). First thing is to look at the specs and go from there or consider other possibilities ( though not interested in Ford, Chevy, nor Chrysler alternatives ). Hope farna drops in with some info. Thank you.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/17/2012 at 6:16pm
I have an article on the Nash/AMC sixes I can send you. PM me your e-mail address.

In general, the old Nash sixes are close to the same size as the last AMC six (199/232/258/4.0L). The bores are smaller, but the castings were thicker. I can't say for sure, but believe the bore spacing is about the same. They are certainly close to the same length. Most have heads with intake made into them like the 196 OHV, with an exhaust "manifold" consisting of a length of exhaust pipe clamped to the side of the block -- capped on one end with cut-outs over the ports like the old 196 L-head. Only the oldest ones have separate intake manifolds. The manifolds were made onto the head to increase efficiency -- fuel vaporizes easier in a hot intake and stays that way, though you do lose a little power due to less dense air. The dual carb setup was simply a new plate on top of the open intake.

"Power for their day" is the key word! The 252.6 Le Mans Dual Jetfire engine used in the 53-54 Nash Healey made 140 hp @ 4000 rpm and 230 ft/lbs at a low 2000 rpm. Solid lifters with 8:1 compression. Specs state and aluminum head, but I'm not real sure about that. Donald Healey may have had a special head made for it that did take a separate intake -- I don't have pics of a Nash-Healey engine. The 54 LeMans six with dual carbs that was optional in the Ambassador was the same block, and made 140 hp @ 4000 rpm, but had 7.6:1 compression. Not torque rating given in "The Standard Catalog of AMC" for the 54 Nash engine, just the Nash-Healey.

Unless you plan on turboing one you're wasting you time with the old engines. The 196 is short for a I-6, the only other I-6 family I know of that is as short is the Ford 144/170/200/250 series. ALL others I've seen, except for the small 2.5L Triumph sixes, are 3-4" longer. So you're stuck for a short I-6 to something other than AMC.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Apr/17/2012 at 8:46pm
  I've seen pictures of Nash Healys with two sidedrafts,  but still with the manifold in the head.
 
  From the picture,  it's hard to tell how they go into the intake passages.  It looks like they come thru the side.  Look up Nash Healy pictures and you'll see what I mean.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Apr/18/2012 at 1:31am
the answer, provided by farna is, all of the Nash/Rambler engines from which the crank drops into the Rambler/AMC 195.6OHV, are all flatheads. Crank compatibility means the bore spacing is the same and (in this one narrow case) would imply that heads would be adaptable.

But basically "our" 195.6 overhead valve engine is *only* the little Nash flathead converted to OHV; it's the only head for this block, in short. It's a really crappy head design.

No problemo, just exploring...

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slate Quote  Post ReplyReply Direct Link To This Post Posted: Apr/18/2012 at 12:30pm
Farna, sent email address for article on Nash sixes. Turbo or supercharging is a part of the plan. I have been considering the 196 OHV, particularly the aluminum block version considering you are at probably 135 lbs or more less than a Nash 6 even with aluminum head, the only question mark being what appears to be an uninspiring head and the different bore spacing not lending it ready modification by using another AMC/NASH/Rambler head on it. A turbo or supercharger would wake it up but part ofthe shortness is because it's only has 4 mains, no?  The next limitation being the relatively poorly supported bores in the open deck design.
If a good version were found ( NOS or low miles with no corrosion issues on the deck surface ) then it might be a good candidate for a blower or trubo after modification to stiffen bore support. If the bore centers were close,the Yamaha designed Aussie Ford crossflow heads would be an acceptable source for a head.
 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tyrodtom Quote  Post ReplyReply Direct Link To This Post Posted: Apr/18/2012 at 2:17pm
  The 196 had a forged crank and rods.  
As far as the intake manifold being a problem,  You'd have to check the heads to be sure,  but I think you could cut the whole manifold side of the head off,  I dont believe there's any water passages on the outside edge of that manifold.  Then you'd have a straight shot at the intake ports.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Apr/18/2012 at 4:46pm
1. The four mains is not a problem. The crank is a heavy forging and the mains are pretty wide. The 196 carries as much main bearing area as most small block V8s. It also has forged rods. The forged crank and rods are because the technology to produce a cast crank of adequate strength wasn't developed until around 63. EVERY engine had forged crank and rods until then. So don't worry about the strength of the crank and rods, or main bearing area.

2. The head has some problems, but mainly in the cooling department. Tomj has devised a fix for that by recirculating some water. The "trough" intake is actually very well designed as far as even mixture distribution. It was made onto the head so the intake would heat up and increase fuel vaporization. It flows surprisingly well.

3. For turboing with mid to high boost (10 psi+) you need a strong block. The thicker and heavier the better. For that reason I'd discount the aluminum block. It still has a forged bottom end but the lack of an upper deck would likely cause sealing problems. Shift isn't an issue -- the siamesed cast iron cylinders are cast into the bottom of the block. Shifting can only occur if the head gets loose, and even then the engine is more likely to run hot and warp the head, not the block. After seeing a couple of these I think the idea of the cylinders shifting is more of a myth than anything. It's possible, but the bottom of the block where the cylinders are anchored is pretty thick and doesn't get nearly as hot as the head.

4. If you're going to build a forced induction 196 don't make it a 196. Bore it 0.040-0.080" and use a 172.6 or 184 crank. The shorter stroke (IIRC 1/4" increments -- 3.75" for 172.6, 4.00" for 184, 4.25" for 195.6) will let it rev faster. There was a guy in the early 70s (have a Hot Rod article somewhere) that ran a 58-65 195.6 block (water pump in front instead of in the side driven off generator) with one of the smaller cranks (forget which!) and either a 0.080" or 0.125" (maximum!) overbore in a 1954 Rambler hardtop. He held the record for his class (under 200 inches) at that track. He had a three speed OD trans with 4.40 gears, IIRC (4.40 was standard in the old Nash Ramblers with the small L-heads with OD). That's the way I'd go.

5. Machining off the side of the head might work, but I don't think so! Would require a LOT of work to get usable ports on top. The trough distributes the mix very good from a central location -- best to leave it alone!

6. I don't know what the bore spacing is, but overall length compares to the small Ford I6. The Aussie head is for that engine (see www.fordsix.com for some info) and it might be adaptable to the 196. I suggest you purchase a 144/170/200/250 head gasket and compare that to the 196 head (or head gasket). That will tell you if you need to look deeper at minimal cost.


Edited by farna - Apr/18/2012 at 4:50pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Slate Quote  Post ReplyReply Direct Link To This Post Posted: Apr/18/2012 at 6:42pm
Thanks both to you and Tyrod. I have looked at Tom J's little site and checked out his fixes. Believe you me I'll check out the Ford specs before attempting to adapt thier heads. next thing, if you have some illuminating articles, is to figure out the bore spacing.
  I appreciate the advice on the Al block, and the thing about the barrels themselves makes sense. However, if I find an undamaged block I believe there is enough to work with to use it even with forced induction. There's been enough open deck designs the past 50 years since to get ideas for a "girdle" on the top deck akin to the idea of bottom end girdles, but this one for the purpose of a bulletproof surface to clamp the heads to. Studs will also help. Logical too, if adapting another head, to find an Al version so we eliminate dissimilar metal electrolysis( modern gaskets and coolant eliminates a good amount of that but they don't elminate different expansion rates which tax a clamping handicapped design.
 
T S
 
ps  have considered the shorter stroke cranks to get the engine close to square at least- displacement isn't important with forced breathing


Edited by Slate - Apr/18/2012 at 6:46pm
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