Souped-up flathead problem solved
 

Long read, but maybe worth it
Last year I wrote in on poor performance and 5 mpg dilemma. This engine is on my ’39 Coupe, ole 50’s Hot Rod with the original Navarro heads and dual carb intake, 97s and tube headers. Before I acquired it, it was put in ‘running condition’ after being taken out of storage in the mid 60s. After a better going over on brakes & tires, etc, I realized that the gas mileage was very poor and that the engine was not pulling as it should. Oil pressure was good, motor ran cool ( thru a 40s truck rad ) but the plugs were black with soot…..terrible rich on fuel. Not going through all of the minute details, all was changed. Plugs, wires, distributor, carbs re-built with .043 jets, pressure regulator, and on and on. Still was not happy, it just did not run the way it should. Maybe the cam was shot, but after close inspection with the intake off, clean engine, Johnson adjustable lifters….maybe not a problem there. Ole Navarro heads would probably have to come off…but dreaded the idea of removing a set of aluminum that have been there for most probably 60 years….heads frozen on the studs came to mind with all of the horror stories leading to total head destruction upon the removable process.
With the hood opened, engine running and discussing all of my problems with a buddy, I just by chance leaned over the engine and pulled of the two Helmet design air cleaners. Now, here comes the shock…the revs picked up by a few hundred rpm!!!!! The light bulb just lit, and I stood there without motion….just trying to realize what had happened. I revved up the engine and slight backfires followed, now that is strange. Drove back the car to my shop, and tried to figure out the situation.
First…the paper filters in the air cleaners were way too restricted.
Second…take a look at this Helmut design cover, and the air intake is very small, about 3/16” air gap around the base.
Third….the timing was now off to compensate for the rich mixture
Forth….the jet size, reduced to .043 became too lean, as the plugs burned white instead of blacky soot.
All of these problems because of bad design air filter covers ( yes, they are the coolest looking and had them on for every test run originally performed ) and cheap Asia import paper design filters…just bought 2 new ones from Speedway….I’ll put them in my trophy room & mark….’Remember this…do NOT use’
How can anything this stupid thing have eluded me for over one year! Don’t believe me….just read in Tex Smith’s book on this VERY PROBLEM. The section on carburetors clearly states this very exact problem.
Fifth….still stubborn on have the Helmut air cleaners, I drilled holes in the base ( see photos ) and forget the inner filters, it would just cover up the hoes just drilled. By the way, I had to drill these holes, because, even without the filter element, the 3/16” air cap entry was still too restrictive….believe me…my tests proved this.
Six…..remember the reduced .043 jets that seemed so important…..joined my trophy room stash of non-used parts. Last year, I bought a set of 97 carb re-building kits from Speedway, and regretted this junky purchase. The supplied .045 jets actually miked in at close to .047, what garbage….but wait, I know have them in the carbs…..seemed to be the perfect size for my setup…..why, you say….again in Tex’s book, it clearly states…two carbs now give you MORE air, and less gas suction from the jets….may have to open up the jets. 100% CORRECT for me. I’m learning….takes a while, but one day at a time.
I am now running the engine without filtering elements….but don’t give a damn. Engine is going like gang busters…yea, had to install a tach to see where the revs were at, it even pulls off generator pulleys and I feel the clutch slipping in high gear under full throttle. As they say….More Power….more problems……but better ones.
Better check those air cleaners…..I acquired enough gray hairs with this. Robert

Re: Souped-up flathead problem solved
 

Forgot this photo......this is what it feels like when that flathead runs great

Re: Souped-up flathead problem solved
 

Love the car..sometimes it's the obvious that alludes us.

Re: Souped-up flathead problem solved
 

If you are not concerned about period correct look, K&N makes air cleaner / filter assembly that fits on the carb, and these flow air real nice, and the elements are
easy to clean.

Re: Souped-up flathead problem solved
 

Robert, I had the exact problem with the paper filter elements on my dual carb set-up. It took me many hours of frustration trying to figure out why the engine was running so poorly....didn't dawn on me that the new filter elements were restricting air flow. Each time I tweaked something with the carbs, e.g., power valves, jets, etc, I replaced the filters before starting the engine. Luckily, one time I left them off, and the engine came to life. I forget where I purchased the filter elements....no doubt they were an off-shore product. Lesson learned. I don't use any filter elements now. Just the louvered style of "air cleaner." I figure the limited amount of driving I do does not pose a problem running without filters. Richard

Re: Souped-up flathead problem solved
 

I had a similar problem and solved it by making my own air cleaner. I used the base off a small air cleaner, a K&N washable filter element and made my own top from .250 aluminum, a stainless steel washer and a stainless acorn nut. You get 360* of "breathing area" around the filter with no restrictions. Works well and doesn't look too bad either.

Re: Souped-up flathead problem solved
 

had the same problem put small filters where they belong and made an air cleaner that dosen't restrict aiir flow

Re: Souped-up flathead problem solved
 

Thanks for sharing.

Re: Souped-up flathead problem solved
 

What brand of soup are you using. Campbells? LOL

Re: Souped-up flathead problem solved
 

I had this same problem. I bought a fine mesh sample pack from McCaster car and did a few layers. It works really well.

Re: Souped-up flathead problem solved
 

K-N air cleaner is the only way to go. I have 3 tall ones on my dragster and 4 a little shorter on my 40 with four 97. 43 jets are perfect on my 40, 42's were a little to lean. My plugs will run white on a trip. Walt

Re: Souped-up flathead problem solved
 

Jetting seems to be all over the place these days depending on the location and who made the carb or jets. On the east coast 43's and even 42's seem to be the answer. Tuning with an A/F meter would solve the guess work.

Re: Souped-up flathead problem solved
 

You are not too far away and it looks like we use the same filter element except I stack 2 of them nowdays.
Here's an old pic with a single.

Re: Souped-up flathead problem solved
 

Nice car. You have great taste. Glad you got the problem solved.

Re: Souped-up flathead problem solved
 

Ol'Ron A/F meter stands for ????

Re: Souped-up flathead problem solved
 

Have a little diffrent setup 390CFM Holley 4BRL. Was told to use the largest housing with the tallest fitler I could get. So I use a tall K&N in a 11" round housing. Works great. Attached is a custom unit I saw on a 50 Ford at a show, looks great!!

Re: Souped-up flathead problem solved
 

Robert, try this website: http://www.obrientruckers.com/
In the Products Search box, enter: air cleaner edmunds and hit enter. The first air cleaner to come up is a neat 4 1/2" diameter cast polished air cleaner with or without Edmunds on the top. They are available to fit 1 barrel, 2 barrel and 4 barrel carbs. $65.00 each. Just put one on my 94 carb. Looks great!

Re: Souped-up flathead problem solved
 

The A/F meter is an Air Fuel ratio measuring device. Cyberdyne makes an inexpensive on for about 50 bucks I use an NGK whide band unit which goes to 16:1. My buddy Richard has one that goes to 22:1. I he idea here is to lean the engine as far as you can go with out hurting it. WOT is usually in the 13's depending on the engine mods and cruise can be as high as 16:1. Doing this will keep the engine running cleaner and last longer giving more power when necessary and better fuel economy when in cruise. A good example is Richards car 3800 lb 52 HD 276, L100 cam and T-5 getting over 20 mph in normal driving. 37 Don 276 in 37 4 dr 19 mph back road trip from Ri To Lake charles and Ron H 296 3200 PU 20 MPG with C4. Tuning can be fun, but you have to work at it.