Hi guys! Just finished my Merc flathead intake and carburetors. Trying to decide which air cleaners to use. The motor will be going into a '32 Ford that I don't have yet! What are your thoughts?
What ever you do, more air is better. Had a new chrome one with a paper element & it choked it bad. Went back to the old screen type & the 8Ba came alive.
It's a good question, and a good thing you asked. Having said that, it has been covered many times here so a search should bring you plenty of reading material. In short, those small ones look nice but choke the engine.
Not flathead specific but a good thread on air filter element size as it relates to CFM air flow. https://www.jalopyjournal.com/forum/threads/o’brien-truckers-tri-power-air-cleaners.1217660/
Damn. Did not know that about the helmet. Mine just arrived on Friday from Speedway. Some I found which I thought were nice... Vintage Speed has some really nice stuff $$$.
I used a Thicksun style air cleaner. I had put oiled foam filter in that originally used for lawn mowers, motorcycles and Dune buggies. No issues with the engine starving for air. I have seen remanufactured copies at the Early Ford Store. https://www.earlyfordstore.com/products/thickstun-air-cleaner?_pos=3&_psq=air&_ss=e&_v=1.0 Sent from my iPad using Tapatalk
You CAN’T feed an engine 2 much air; it will dictate how much it needs. More air require bigger jets to make the proper air fuel ratio. I bought a K & N style for a Porsche 6 cylinder at a swap meet. Cut out the base out of aluminum—did the same with the top—-Porsche filter in between. Stock jets in Stromberg 97’s are .045—went to .046 with the better flowing K & N—seems just right! 32 Henry cabriolet runs 80 in the 1/8 with gm 5 spd and 3:89 Locker at the track.
Grace and Company for the win when you quit playing with the helmets and such....that is if you want plenty of airflow AND you want filtered air. Of course if you don’t drive it much or don’t care about your rings, take the filter out of the helmets....it’s the only way they’ll flow any air. Been there and done that.
If you want helmet type air cleaners that work without restricting your airflow, consider the ones manufactured by Wolk Designs. https://www.hotrodhardware.com/index.cfm?ptype=product&product_id=1939&category_id=1031&mode=prod After doing some research several years ago on this same subject, I seam to remember that the ones from speedway only have 1/8” gap around the base and the ones from Wolf have a 1/4” gap around the base. Hope this helps in your decision. Sent from my iPad using Tapatalk
Also, be careful with K&N elements. I have found they flow less than regular pleated elements the hard way. This has been discussed here before.
My plugs were always fouling, so I kept jetting down with the bell helmets. There's not a lot of space between the base and cover. On top of that, the elements are too small. I removed the elements and drilled the bases for more air flow. I then had to jet up.
I have run the helmet style with a very free flowing filter , I spaced the helmet up higher so around 1” of filter was visible and more air available ,my top also had the small louvers. On the grace and co ones which from the factory have no filter. as we live on an unsealed road , I found a small free flowing lawn mower filter element and fitted slightly taller SS mesh on twin 81 carbs on a 4 banger.
Be careful here. How do you define "free-flowing"? I remember seeing a chart that gave the CFM capacities of various OEM filter elements. I was quite surprised to see how large a filter element had to be to pass a significant amount of air. I too, was looking to see if there were any small engine elements that would suit my purposes, and none were even close. It just doesn't make sense that an air filter suitable for a 12 ci 4 cycle engine to come even close to being adequate for a 239 ci engine. That's a 20 times difference. I have spent the last 5 minutes searching for that chart, but could not find it now. If I run across it in the future, I'll be back to amend this thread. I am running a 2G on the '51 Merc in my car. I ended up using a filter from Speedway motors with an 8" diameter element 2" high. After some preliminary calculations, I made an extended center stud that allowed me to stack two elements, giving me a total of 100 square inches to feed a carburetor capable of flowing 250 CFM. A little basic calculation gives you the need to be able to filter up to 432,000 cubic inches of air every minute. All of a sudden, 100 square inches doesn't seem to be a lot. I am sure there are some engineers out there that can shed some more light on this, but at this time, as far as air filters are concerned, read my signature line.
I used the Edmunds Tall air cleaners from speedway motors. The bases are rubbish so I mounted them on my old helmet bases,
so for the guys that have no filter, but just a bug screen, as shown in the post above, can they have too much air pushing in, especially those with no hoods, does a windy day or higher speed force more air through than required, thus affecting fuel air ratio and either too lean or too rich a condition ? I read this on another thread and just curious.
I have been searching for another pair of grace and co air filters , only can find 1 so far. Are they still being made?
I used my old lid ,taller element with longer stud and wing nut . Tight fit but they go in chrome lid . Filter # 2158 Napa. Again tight fit but pushed them in .
An AIR CLEANER has to be able to remove dust and sand to be an AIR CLEANER. If it just has a screen its a bug catcher.
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