Help diagnose slightly modified 39 Flatty

19ED30

19ED30

Senior Member
In my 32 , I have a slight modified 39 Flatty, with 39 Trans ,
Offenhauser Regular Dual with 2 94 , Mallory ignition ,
Edelbrock heads ,Open Edmond air filter with K&N elements ,
2 psi to carb's .
Timing 8 deg at 700rpm
Total 27 @ 1800

The issue that I am having ,
1st gear to 3,500 rpm to 2nd Gear No prolblems
2nd gear about 2400 rpm it starts sputtering or Missing
to 3500 rpm ,
3rd gear around 2800 rpm sputtering or Missing !!
I do not know if the bowl's are going dry , I would not think So ,but may be
Because the gear ratio in 2& 3rd
My Electric fuel pressure gauge shows 2 psi at all times & I verify with another gauge but may be no Volume ,
 
If you have the same fuel pressure under all conditions that cant be the issue ??
If there wasnt enough flow the pressure would drop...
 
That's a lot of advance and it comes in early. 20 degrees (or even 18) total is more common and full in around 2000 rpm. May or may not be a factor, but way more than I would want to run.
 
once it starts to sputter, quickly push in clutch and turn off engine, coast to a stop, get out and check the fuel bowl for fuel, work the throttle lever to see if you get fuel squirting down the carb, either one should show if you have a fuel problem, but the one thing I would do instantly is get rid of the Mallory ignition, there nothing but problems, I have removed a half dozen of them to fix problems like your posting, but Mallory is not the only one, msd, and pertronics have the same flaws, get a dual points dist, use top quality usa made points condenser and usa made high voltage coil, keep the dist cam lubed and you can go 30,000 miles with no problems, and you can fix it on the road, my son had a 68 ford pick up with a Mallory dist on it, missing no power, fouling plugs, went to get a new cap and rotor, the cost $50, so I bought him a new one wire chevy type hei one wire dist for $60 , no more problems, if any thing goes wrong, go to parts store and buy the parts for chevv HEI dist
 
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I had a similar problem. Turned out that when I put a vendor buil fresh turnkey motor into my '35 it came with a Ballast resistor mounted prior to the distributor. I hooked all up not thinking much about it and had the issue you are having or very similar. Turned out I was running on two resistors in series, the one supplied with the fresh engine and the stock one under the dash. Disconnected / wired around the under dash unit and problem solved.
 
Thanks to all , I will still keep at it , I am going to try a few other thing , if I still can not find the prolblem, I will Change intake & try 1 carb , a Rochester 2 barrel, I have a adapter for this , I have read that a flat head need around 250 -300 cfm's
I have Ran Mallory in the past on Chevys even with Blowers & on Nitros with no issues!
80s- 90s distributer, But I have heard several say that the Mallory's for the FlatHead Have prolblems , Are these distributer made in 2000 up ? What are the Issues?��
 
A Flathead doesn't "need" 250-300 cfm. They run great on one, two,three, or four 94's or 97's, 390 or 465,600 Holley, 500, 600 edelbrock/Carter/Weber, blowers of varying sizes, injection. In various tunes any of these, no "need" your problem ain't that it's got two carbs.
First port of call is the red cap of disappointment, I haven't seen one with a flathead ignition curve in it, in my experience they have a sbc curve from factory! That's a big reason why they work great on the chevy monkey motion and not on a Flathead. Yours has much too much advance. Your engine I'd start with 4 initial and 18 total, this takes into account the high compression heads, stock cam and regular dual, this is as a starting point. And 3-4 psi on on the fuel pressure for 94's.
If its a front mount ignition, a stock Ford ignition would be about perfect! With a stock port and stock cam engine it should rev clear to 5000rpm, though power will drop off above about 3800ish.
Have a play and report back.
Martin.
 
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Forgot,
You say "32" is it a fender less lightweight or full body sedan? What gears you got up it?
Light car with proper gears up it, 18ish degrees all in at 1800 rpm should be great, heavy car with lazy arse cruiser gears will like it all in a bit later.
Were talking mechanical advance only.
Martin.
 
Scooder , I would say that gear ratio in about 4:10 , 28 inch tall tire ,60 mph @ 3000 RPMs .Steel Full fender Sedan 2dr. Car was Restored / Modified in 98 , for a 80 year old gentlemen , in 15 years car was only driven 600 miles ,( modified as in 40 brakes ,39 motor and trains, 2 carb's , heads ,& modern Mallory, 12 v gen,)
I was told motor was rebuilt in 98,
Cam sounds to be stock ,
I have had it 4 mouths and drive It 200-300miles a week ,I run Delvac 15-40( no filter) with no oil add be tween oil change (every 2000mile )
This is my first flat head , I do no think I had ever drove a car with 80 or so hp .
My 30 Hot Rod /Race car has 8x that hp with 1000 cfm's.
I have read that flatheads form factory where severely under Carbureted,
I was thinking ( 39 Flatty )it needs about 250 -300 cfm's ? Two 94 about 265cfm's ,
I checked the timing & also made sure they wired the Mallory correct , it was!!
Timing 8 , total 23 ,
I have a ford 2 bolt crab distributor ,I will install and try it , I just do not like not having one of my car to drive , the other one ,I have motor out freshening it up ,
I will also change fuel pump , If distributor does not solve my problem
 
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8 initial and 23 total is better, but still probably to much. As Scooder suggested, 18 would be better. Timing has a lot to do with the combustion chamber shape and there is a lot of difference between a flathead and an OHV combustion chamber. Your best bet might be to have the distributor re-curved by Bubba.

By the way you should be getting more than 80 hp out of it.
 
8 initial 23 total, try retarding the ignition 4 degrees, that would give you 4 initial and 19 total. See what happens, if it gets worse down the bottom but better up top, get inside the Mallory and shorten the advance. Then you could have 8 initial and 19 total. Or the other way round.
The one thing I do like about the Mallory is its adjustability.
I'm not saying the issue is all in the ignition timing, but getting this where it should be is a good start. Important to try one thing at a time, otherwise you'll be chasing your tail.
Have a play.
Martin.
 
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3500 runs good , 2nd gear has missfire and third gear missfire ....
to me thats a load induced issue with low ignition output under 2nd gear loads etc.
Check coil , coil wire (both ends) and primary ressitance .
What coil are you running.........??
 
Up dated , problem solved .
I have tuned many carbs over the years ,by useing shiny shank spark plugs ,
But this New blend of Unleaded gas will give you false information ( plug reading)
Pulling my last few strains of hair out ,
I remembered that I had a brand new Autometer wide band O2 gauge kit ,
So I raised car up ,drill a hole in exhaust pipe , weld the bung in , 20 minutes later ,
Bang !!! Lean , main jets 50's , Rejeted carb's 52s
Test drive ,
Removed O2 and gauge ,screw in block off plug , Done !!!!
 
BUBBAS IGNITION said:
3500 runs good , 2nd gear has missfire and third gear missfire ....
to me thats a load induced issue with low ignition output under 2nd gear loads etc.
Check coil , coil wire (both ends) and primary ressitance .
What coil are you running.........??
Click to expand...

I was going to suggest the coil as well. My '36 was giving me FITS for weeks last year. It would flutter at certain speeds and loads, the engine would miss at other times. It wasn't right and it drove me crazy. I pulled the distributor and rebuilt it at least 20 times swapping rotors, caps, condensers and even distributor bodies. I tore the carburetor down, swapped it out, changed several plug wires and did more that I can't remember. Ultimately the car became nearly undrivable and the coil was the last part of the equation I tested. The brand-new Pertronix unit failed me in less than 1,000 miles. I swapped it out with a Bosch unit (No. 00012) that Bubba suggested and all of the problems DISAPPEARED.

264201
 

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