The big blue air cleaner on a 289 has a thermostatic flapper in the air snout to heat the air to the carb to around 100F using exhaust manifold heat. The '66 shop manual on page 10-6 gives steps to test the thermostat in this snout: Air Intake Duct Valve Test 289 V-8. The simple test removes the air snout and sticks it in water to see if the flapper is open or closed. With water below 75F the flap should be open to admit exhaust heated air. Above 100F the flap should completely close off the exhaust heated air path. Could someone with a '67 shop manual tell me if the test was different for 1967?
Why I ask: I have two, blue air cleaners for two 289s, one a (March) '66 the other a (January) '67. Other than the date code the only difference I knew of between these two was the snout on the '67 is about 3/4" shorter than for the '66. The snouts look the same until you measure their lengths. (Repros are sold as if the two years were identical which they were not.) However, my two air flapper valves inside the snouts are also different. The thermostatic pusher is the same in both but both the actuating rod on the '67 flapper is longer and the angle of the tab on the '67 flapper is such that the '67 flap can NEVER fully open. If it is to close at 100F then its maximum opening is about 1/4" even at 20 below zero. The '66 flapper goes from fully open at 70F to fully closed at 100F. I am trying to decide if someone put the wrong thermostatic pusher in this '67 or if it was never intended to do much of anything.
Secondary question: The late '66 289s, after May 1966, used the more squarish '67 style valve covers. Might they have changed to the '67 style air cleaner at the same time?
I may be able to shed some light on your question (or may be not...)
My car is a San Jose car and had a scheduled build date of 20 Jun. I still have the air cleaner and after some searching did find it. It is stamped 6F and the length of the snout is just under 8 inches and to my untrained eye, the flapper could fully open.
I do have a question back... my car does not have the 65/66 horns but the 67. Do you know if they phased these in early or someone swapped them in later.
Thanks for your data. I can't answer your horn question. I didn't remember that the '67 horns were different and its been 20 years since I owned a '67.
In the Bob Mannel SBF book I found a picture of long vs short snout air cleaners and the long one was still used in Nov 66. So it appears that even early '67s would have still had the longer snout. The long one is 8" total length but without removing the snout, the distance from tip of snout to the mounting flange at the air cleaner (measured on the top side) is 7 1/2" for the early version and 6 5/8" for the later, shorter ones.
Your car is close to the one I am building (21 Jul San Jose). I think they both would have had an air snout flapper that opened fully especially since it seems the shorter air snout didn't happen until around Jan '67. I'm still curious about this '67 one though.
I think I know that my car should use the longer snout with fully opening air flapper but I am still curious about the 'other' one I have.
This mystery snout is actually from a '67 Cougar: 7F91C555739. I think that says Dearborn, Std 2-Dr Hardtop, C-code 289. The snout date code is 7A, January '67, which was consistent with its owner's manual delivery date.
How does the Ford shop manual for '67 or possibly '68 Mustang OR Cougar describe the air snout operation? I doubt it, but could the operation have been different for '66/'67 or Mustang/Cougar? For 1966 Mustang the shop manual description of how its to work is in Part 10-5, section 1 (page 10-60, Air Cleaner) while the actual test using heated water is in Part 10-1, section 1 (page 10-6 Air Intake Valve Duct Test). Might the operating temperatures for later cars (fully open/starts to close/fully closed) be something other than 75/85/100 F?
I never did get data for a '67 air snout but I now think it would be the same as for the earlier cars. Playing with my two snouts for a few days I think I have answered my own questions. I also unearthed the patent to which this device was built: 3,450,119 granted in 1967 and assigned to Ford Motor Co - naturally. A sketch of the snout parts from that patent is attached since its easier to see everything I will be talking about. I will refer to parts by their numbers in that sketch.
The thermostatic air snout with an air tube to the exhaust manifold of the small block V8 engine first appeared on 1963 Fords. The same snout and tube hardware was continued on the lower profile Mustang air cleaner in '64. I have tested two snouts from Dearborn cars: 1) a March 66 car with 5M/6B air cleaner/snout and 2) a Jan 67 car with 6L/7A air cleaner/snout. Air cleaners with dates 2-3 months older than the car seem to have been normal. The two snouts differ slightly but their intended operation is essentially the same and described in the shop manual pages I referenced above.
When removed from their engines recently neither of these devices worked. After 40+ years there may not be many of them that do work? But in a similar 40+ years of playing with these engines I have never seen any mention of how this thing operates or that its important to even look at it. Usually it gets tossed aside with the original air cleaner so a shiny chrome one can go in its place.
The thermostatic unit is the top-hat looking widget shown at the extreme right of the sketch. To see it, take the thumbscrews out and look into the air cleaner end of the snout. It is a wax pellet thermostat with a removable, 0.118" brass rod about 1 1/2" long sticking out that mates into the end of #78. When the snout gets hot the rod pushes #78 to the left causing flap #34 to close. When it all cools again the thermostat does not itself retract the rod. Instead all the springs involved, mostly #75, have to push the rod to the right. If you unscrew and heat the thermostat by itself it will push the rod out 7/16" but the rod will then NEVER retract unless you force it back somehow.
The '66 snout I removed had probably never worked since it left the factory. The small brass rod was bent about 15 degrees and jammed into the bore of the thermostat so it could never move. Straightening the rod, testing and adjusting it the snout now starts to move the flap at 87 F and has it fully closed at 109 F. Not too much different than the 85 and 100F in the shop manual. When going back and forth from a pot of 70F water to one of 109F water it takes a minute to open the flap and 3 minutes to close it. The stroke of the rod movement is not quite enough to fully open and close the flap so I adjusted it so it fully closes off the exhaust air when warm and opens about 90% of the way when cold. The rod motion is all between 87 and 109F with essentially no additional movement all the way up to 170F which is the hottest I tested.
Since this part has never worked I can't yet say what difference it will make during the warm-up phase of engine operation to have it actually open and close.
The '67 snout essentially did not work at all. It sometimes wouldn't move at all with heat changes and, if it did move, it would sometimes open when heated instead of closing. The problem was that the thermostat would always push the pin out but the pin was bound tightly in the thermostat bore somehow so the springs involved could never retract the pin and close the flap. I could force the pin back in a vice, but it would not retract by itself with the springs in the flapper unit. Heating the thing sometimes allowed the pin to retract as the bore of the brass thermostat expanded with the heat but that was very sporadic and also caused a 'wrong way' motion.
I was afraid solvents might kill the thermostat but, since it didn't work anyhow, what was to lose? I tried lacquer thinner, WD-40, gasoline, etc. I finally filled the thermostat bore with Kroil overnight and then the next day it sometimes would work poorly. I did the same last night and now today the thing finally works like it should. Its now better than the other one; maybe I should have soaked the other one as well? Once freed up the '67 unit starts to open at 90F and is fully closed at 110F with a full 100% open/close movement.
#78 in the '67 snout is about 1/4" longer than in the '66 unit and tab #42 on the flap is bent at a different angle. I think the changes were to put more #75 spring pressure on #78 to force the brass rod back more reliably. Those changes mean the thermostat unit on a '67 is not threaded nearly as far into the snout as on the '66. The tophat on the '66 sticks 1" above tab #64; for the '67 it sticks up about 1.5" and the thread of the thermostat is barely engaged into #64. I actually shortened the brass rod in my '67 by a 1/10" so the thermostat threads more securely into tab #64.
Otherwise the operation of the two unit is - now - much the same.
A minor correction. The patent was filed in 1967 and granted in 1969. Seems they should have done that a little earlier since they were using the thing in 1963! There likely was preliminary work which delayed the official filing date to 1967. The patent also includes a vacuum servo to close the flap and bypass the heated exhaust during full throttle acceleration. Ford must have decided that part wasn't really needed for an early Mustang.
Thermostatic air snout: 1966 vs 1967 
