I appreciate the rep Chris ! The true deserved reps are for those who contribute to FTE in real time, unlike other forums that "may" respond in two,three or more days with haphazard info....Henry would be proud of FTE !
BTW....the GGrandson is now fast asleep in his Ford onesie with footies.

 

The easier solution is to add a spacer between the car and air cleaner. This will get the lid up off the carb. It won't do any thing to increase the filter area but it will provide more space between the carb and air cleaner lid and help smooth out the transition in to the carb.

 

In my experience, the hot air stove has enough flow to it that it doesn't seem to choke the engine any during normal power demands.

I have never been able to be under the hood to watch it, maybe matthewq4b you know the answer to this. But I am thinking if you are in full on heat mode and suddenly dog the engine for some power, that might reduce the vacuum enough in this system to let it go ahead and open the door anyway, since there will be no vacuum generated by the engine. This may not work though, they usually put a doo-hickey in the line to the flapper door vacuum motor, and I think it's some sort of restrictor, which may prevent the door from opening unless you held the throttle open for 5 minutes.

And one other thing that has not been mentioned in this thread, the heat riser in the exhaust manifold. On most of my Fords the heat riser is usually broken, so I don't use it, I use the aircleaner for carb icing problems. But I have had other brand vehicles that had better heat riser systems that did not fail, and I have been able to run open air cleaners on those vehicles where the heat riser actually worked. It put enough heat under the carb to keep it warm and not ice up.

I haven't tried it on a Ford, but if you did want to get your heat riser working that may be a solution you could try that may work better for some people.

 

The Hot air idle compensator is for high under hood temps when fuel evap in the carb is high and can lead to hot stalling.

The Ported vacuum idle kick up is for high coolant temps or when the AC (if equipped) is on.

The AC condenser dumps a lot of heat right in front of the rad reducing the effectiveness of the radiator. If engine temp rises to high (usually around 212) the ported vacuum switch feeds manifold vacuum to the dist thus increasing the engine RPM by advancing the timing thus increasing coolant flow, and since the timing is also now advanced it reduces the combustion temps thus helping lower the amount of heat the engine is producing.

 

Forgive me if I'm completely in left field here, but what about turbulence? It's been mentioned a few times, almost always in the context of the need to minimize it. But is turbulence at the carb inlet always a bad thing?

Questionable analogy: Inside the combustion chamber. Engineers generally want some turbulence to help mix the air/fuel and promote better combustion. I've done some flathead tuning and one important lesson there is to NOT overdo opening up the shallow passage between the valves and piston. Even though a shallow passage reduces the breathing ability, it also increases velocity and turbulence. This in turn does a better job of scouring the remnants of the last charge, and mixing the fresh charge. Dyno tests have shown better breathing from a wider passage actually reduces power. This seems counter intuitive at first until you think about forced turbulence.

So is it possible SOME turbulence (but not too much) at the carb inlet is desirable? All this talk about clearance with the air cleaner lid got me thinking about my old flathead (still talking about engines).

Cue the laughter...

 

THIS is going to be a big one.

Like a lot of guys here, I like the factory air cleaner because of better-behaved wintertime driving... when I was a 16 yo kid and had my first-ever car (1970 Mustang fastback 351W FMX) one of the first things I did is remove that God-forsaken ugly thing and install a shiny, chrome, open-air thing...

...it definitely didn't prefer winter weather that way.

Now that I'm older, I'm better understanding the benefits of not doing that... and so, when I put together my own truck engine, I installed an air cleaner from a 70s sedan, I wandered around the junkyards and got 2-3 of them for something around $10 each at the time for the assemblies.

And I looked at the varying configurations of these things, the varying PCV configurations of the 70s sedans, and know exactly what he's talking about re: sometimes a baffle right at the snorkel/filter junction.

And so I'm interested in this, too, just to see what you guys have to say about this.

 

Have a look at the inlet in to the air cleaner is it about 2" in dimeter maybe less. Would you feed a 351 or 400 CUI engine through a 2" hole ? Not to mention the heat shroud is right up against the exhaust manifold.


As for the flapper being pulled open you would have to generate enough vacuum the air cleaner to over come the pressure holding the flapper closed
and this will do what to your fuel air mix ? Exactly the same thing as having the choke on.


If the shroud is missing on the exhaust manifold disconnect your heat riser flapper. As you will not properly heat up the air cleaner and the flapper will always be closed or closed for far far longer than it should and you be trying to feed the engine air through a 2" hole it will be equivalent to having the choke partially on..

Remember the heat sensor for the flapper is inside the air cleaner no heat from the riser due to a missing shroud no heat for the sensor to open the flapper.

 

Are you feeling young yet, @Gary Lewis?

 

One thing you will learn about us, Matthew, is that Gary never chooses the easiest route for anything... he is the creator of the 8-page microanalysis....

 

Could part of the baffle's function be to cause a sudden change in the direction of airflow? This would help settle out any crud carried in the airflow, and drop it harmlessly onto the bottom of the air cleaner housing. Imagine driving through a swarm of bugs, for example. If the bugs kept moving with the airflow, they'd all end up plastered on the face of the filter, potentially clogging it. With a baffle disrupting the airflow, most of the bugs might fall to the floor of the air cleaner housing.

That's the basic premise of oil bath air cleaners. Airflow travels straight down and makes an abrupt 180 degree turn straight up above a shallow bowl full of oil. Debris is heavier than air and is launched by centrifugal force into the oil where it is trapped.

Back to your regularly scheduled laughter...

 

Well, my grandson isn't here and that wasn't me saying that. But, given all the work I've done on someone's trailer of late, I'm not feeling young.

Having said that, my thread on the to-be trip is at 12 pages and I haven't left yet!

 

Which Flathead ? I have two. A 109hp in a 51 Merc and a flat Six in a 49 DeSoto...both bone stock with oil baths and fuel bowls.

 

Truth has never been told.....Gary always chooses the high road !

 

Valid question. But you do not want turbulence at the carb. Turbulance can be described as high and low pressure areas jumbled together in no order. Now a carb meters air and fuel mixing based on flow and pressures.

All of the metering orifices are at the throat of the carb if you have uneven pressures in this area and uneven flow it is going to affect the operation of the carb and in turn fuel metering affecting power and efficiency.

 

It will have affect on this but if that was the case is would have been universally used on applications that had more direct air inlets. But such was not the case and lots of units like the bullnoses that have one of the most direct air inlets generally do not have it. It's primary use was as a noise baffle to dampen inlet noise.