196 OHV Port Configuration - and Porting

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   I'm in a 'working on many cars' mode at the moment. I had to shift my
 spare 196 OHV head out of my Corvair wagon (aka "storage shed") but had
 room on the work bench so I put it there. Today I decided I had a spare
 1/2 hour and popped the valves out. With a little steel wool and brake 
parts cleaner I was surprised to see how clean the seats were. I'm 
guessing this head might have been redone not too long before I got it. 
There are bronze guide liners on the intake valves and shims under each 
spring. The valves have very little lateral movement too. So,  a lot to 
be grateful for. I picked it up at Pick Your Part in Sun Valley, CA  
w-a-y back in 1996 and I've had it in storage all that time. Back then 
it was $15 and that included the rocker shaft/arms, oil filter mount, 
portions of the carb linkage, the coil mount and the intake plate (one 
of those with the tube running through its center - nitrous spray bar 
anyone?  ). Well, those days are sure gone now.

 Anyway..., the point of my post is the ports. There is absolutely no
 short side radius??? In fact the cut for the bottom of the seat creates
 a 90 degree sharp edge at this non-radius short side. I've modified 
an illustration to.., well..., illustrate it in red (see below). What were they 
thinking (or drinking)? It is everything I've read NOT to do when 
porting. The only thing I can see to do is 45 degree or round off that 
sharp edge on the non-existent short side. I realize these are not race 
engines. But I just can't pull a head (especially if the valves are 
coming out) and not take a grinder to them. It is kind of like if you 
are going to cook a steak then be darn sure and spice it up too! So, I'm
 just looking for comments, experiences etc. with the questionable 
configuration of these 196 heads.

Edited by wittsend - Nov/10/2021 at 7:22pm

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wittsend Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Apr/15/2020 Location: California Status: Offline Points: 425	Post Options Post Reply Quote wittsend Report Post Thanks(0) Quote Reply Topic: 196 OHV Port Configuration - and Porting Posted: Nov/10/2021 at 7:17pm
	I'm in a 'working on many cars' mode at the moment. I had to shift my spare 196 OHV head out of my Corvair wagon (aka "storage shed") but had room on the work bench so I put it there. Today I decided I had a spare 1/2 hour and popped the valves out. With a little steel wool and brake parts cleaner I was surprised to see how clean the seats were. I'm guessing this head might have been redone not too long before I got it. There are bronze guide liners on the intake valves and shims under each spring. The valves have very little lateral movement too. So, a lot to be grateful for. I picked it up at Pick Your Part in Sun Valley, CA w-a-y back in 1996 and I've had it in storage all that time. Back then it was $15 and that included the rocker shaft/arms, oil filter mount, portions of the carb linkage, the coil mount and the intake plate (one of those with the tube running through its center - nitrous spray bar anyone? ). Well, those days are sure gone now. Anyway..., the point of my post is the ports. There is absolutely no short side radius??? In fact the cut for the bottom of the seat creates a 90 degree sharp edge at this non-radius short side. I've modified an illustration to.., well..., illustrate it in red (see below). What were they thinking (or drinking)? It is everything I've read NOT to do when porting. The only thing I can see to do is 45 degree or round off that sharp edge on the non-existent short side. I realize these are not race engines. But I just can't pull a head (especially if the valves are coming out) and not take a grinder to them. It is kind of like if you are going to cook a steak then be darn sure and spice it up too! So, I'm just looking for comments, experiences etc. with the questionable configuration of these 196 heads. Edited by wittsend - Nov/10/2021 at 7:22pm
	'63 American Hardtop

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Nov/10/2021 at 11:57pm
	Umm yeah, it's pretty terrible. It's the early 1950's in there. A friend had a head for a Nash 252ci six in his pickup bed, I looked at it as best I could, expecting to see ... well I don't know, but something better than the 195.6 OHV. WRONG. The 195.6 OHV is improved over the Nash six, which was allegedly a decent motor. It's awful. No idea about flow, but manufacturing-wise, it's awful. Probably represents the state of the art of casting (limitations). Spark plug recesses were steel tube inserts (12 opportunities to rust and leak), the trough is 1/2" wide! My thumb won't go in it, the trough cover is more complex, etc. THe 195.6 OHV is a substantial improvement over the Nash six. Let that sink in. It's just old. When I was building my roadster's previous motor I too wanted to clean up ports, mostly those sharp edges. TO get an idea of where it woudl be OK to remove metal I sliced up a bad head. (It was really bad, 6 or 7 cracks). https://www.sr-ix.com/AMC/195.6ohv/HEAD/Cylinder-head-dissection/ I settled for knocking sharp edges off and equalizing the middle exhaust port by filling in the carb-preheat chamber. THe exhausts aren't too bad; short, wide-ish and straight shots to the manifold, though they dump a lot of heat in the head I think. THe intakes are hopeless. I got all the casting roughness smooth, for what little that's worth, and some overhang near the seats. And the angular crap aroudn the guides. When I blew that engine up the high-end pro that built the current motor (Peter Fleming) did some more cleanup, I don't know what, and thinned, undercut, the valves themselves. I think that motor is as badass a$$ as a 195.6 OHV is gonna get, FWIW. The pop-up piston design is fundamentally bad. There's too much surface area, and all in the head, so heat transfer is high. There's dead space around the popup. This was necessary because the trough head is simply the flathead design moved into the cylinder head, preserving all the bad thermal features. As a thoguht experiment I considered making a cylinder head from scratch, in three layers, so it could be milled on a regular mill. For flat top pistons. A combustion chamber layer with valve seats and ports, a middle layer with most of the port runners and water jacket, a top layer seals ports and water jacket. Certainly I'm not gonna do this.
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

farna Members Profile Send Private Message Find Members Posts Add to Buddy List Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19676	Post Options Post Reply Quote farna Report Post Thanks(0) Quote Reply Posted: Nov/11/2021 at 6:47am
	That's an interesting way to make a head -- would work! Sure you're not gonna do it? Heck, make a wood mock-up.... The only way to improve the 196 intake flow as I see it would be to ADD material in the bottom to make a short side radius. While it would reduce port volume it would increase flow due to a better path. That's why the 2000-06 4.0L heads work a little better than the earlier larger port heads up to about 3500 rpm (after which the larger port is slightly better). Smallest ports of all the late model AMC six heads, but much research was done on port shape to give good power where most needed on a street vehicle and improving combustion for better emissions. The 252 Nash engine dates back to the late 20s, so no surprise the design has "issues" compared to modern standards. The 196 (flat head) came out in 1940, the OHV head in 1956 -- it's "modern" compared to the bigger, older Nash OHV sixes.
	Frank Swygert

wittsend Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Apr/15/2020 Location: California Status: Offline Points: 425	Post Options Post Reply Quote wittsend Report Post Thanks(0) Quote Reply Posted: Nov/11/2021 at 2:42pm
	Yep, that is the area (red arrows) right there (thanks for the pics link). For those that don't know the area between the red lines should be a smooth rounded area, not a diving plunge and sharp edges. The goal being to smoothly turn the fuel/air mixture so it is moving downward on the back of the valve. It should be a radius. Also that sharp edge where the blue arrow is pointing needs to go. BUT, that is part of the seat! I'm thinking a small ball cutter and ever so slightly working the edge but very much from the back side only. You can't get rid of the ridge without taking the seat but m-a-y-b-e it can be made a bit smoother. Some more irony is that the already discussed oversize port for the intake seat area creates a ridge..., well the undersize area under the exhaust seat also creates a ridge contrary to flow direction. I mean if you had to be stuck with a ridge they should be reversed so the effect is lessened in the direction of flow. The good news is I spent as little as 30 seconds on the exhaust side and that ridge is now gone. On the intake side the ridge behind the seat just can't go away. But with a Dremel, a thin diamond bit and careful movement in about 5 minutes I got the sharp edge removed without compromising the seat. This was just testing. I'll spend more time later perfecting this later, it isn't finished work.
	'63 American Hardtop

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Nov/12/2021 at 11:49am
	Here's the old Nash head... "enjoy" (painful). I remember the trough as narrower. It's pretty narrow. This head is pretty much the L-head port configuration, moved up to the removable head. Talk about conservative! The head bolt spacing is even, at least. The 195.6 OHV bolt situation is terrible. "Our" engine is a substantial incremental improvement over this old thing. This bigger Nash motor is possibly more reliable though.
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

wittsend Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Nut Joined: Apr/15/2020 Location: California Status: Offline Points: 425	Post Options Post Reply Quote wittsend Report Post Thanks(0) Quote Reply Posted: Nov/12/2021 at 8:23pm
	I got the 196 OHV head, purchased circa 1996 for $15 head cleaned up today. It has the appearance there are replacement hardened seats (unless they came that way) and confirmed bronze liners on the guides! Nothing special on the porting. Unfortunately the flash rust doesn't show the exhaust very well and I did most of the work there. Frankly the 2 into 1 exhaust and the trough intake don't allow much in the way of porting. My goal was to just remove flashing cast, sharp edges (especially where the Intake seat meets the bowl on the short side) and blended the remaining bowls in beneath the seats. It's a hobby, not a profession. Some people do needle point, I have a grinder and dream I'm Joe Mondello. Edited by wittsend - Nov/12/2021 at 8:42pm
	'63 American Hardtop

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Nov/12/2021 at 8:42pm
	That looks pretty decent. I've had a dozen heads through here in recent years. Nearly all of them had been redone. Lots of replaced valve seats, staked into place. But I Can't remember many/any bronze guides. At the flows this engine is even theoretically capable of -- at 4500 rpm the theoretical 80% VE flow is 203 CFM total, or 34 CFM per cylinder. And none of us have cams that could make ports become a limit. There's no blanks available, no meat on the stock cam to regrind worth bothering with (though I have, twice). A single Weber IDF 40 is TOO LARGE. It can be tuned, however, so it's not technically too large, but it doesn't drive as well as the 38/38 DGV, on my roadster, and I relatively-speaking rev the crap out of that engine. The 44 IDF cannot be tuned for drivability at all. At 3000 rpm that's 24 cfm... ! lol
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com

tomj Members Profile Send Private Message Find Members Posts Add to Buddy List AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544	Post Options Post Reply Quote tomj Report Post Thanks(0) Quote Reply Posted: Nov/12/2021 at 8:44pm
	I don't mean to say you're wasting your time. Nice work always pays off, directly or otherwise. Detonation, crud build-up, flaw-finding, etc. ALso it just looks great!
	1960 Rambler Super two-door wagon, OHV auto 1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com