Technical Flathead carbs

Have 53 flathead running two speedway motors repop of the sromberg 97, .045 jets and 65 pv.With super dual manifold, running way too rich, plugs are black and fouling. Don't know if carbs are just too much for motor or what. Got a mallory magnetic breakerless distributor, promaster super coil, 8.8 mm wires and B6HS NGK plugs. What can I do to lean this monster out

 

Try smaller jets, 42 or 41, never heard anything good about those Stromberg knock-offs from Speedway.

 

Sounds like same issues w/my 51 flathead in avatar 39.........running 3 repop Stromberg 97 on Navarro intake......started out with same jetting as you, now down to .42 in center carb, pv is 67, also Mallory electronic distributor..........fuel line pressure down to 2 #'s.........still has rich smell, etc and carb's are prone to puking raw gas into intake manifold.........runs OK, but still not there.............

 

Thanks for The help, have had fuel pressure as low as 1.5 lbs, .042 Is where I'll start, thanks again

 

1. It is a look a like, not a reproduction.
2. Search Speed Super 7 or whatever they are called on the HAMB, lots of threads. Be prepared for unfavorable news.

 

unless you are going to race it- alot of mult -carb set up dump way to much fuel.make a thin plate and block one carb off- also block fuel to it off. that way you have a smooth running engine for sreet use with the looks of a racer. no more fuel dump.

 

Doing the math, cfm to ci, way too much. I thought about blocking one off and trying one carb, dose it matter which one, front or back

 

So instead of making two carbs work properly, you'd go to a multi carb manifold that won't be working properly (distribution) with only one carb functioning and one decorator one. That's like out of the fry pan into the fire.

 

Having a dual carb manifold with one blocked off, just for show, is like kissing your sister.

 

I haven't had any more problems with these carbs than the 94s I was running, just too much fuel, jetting down is my best alternative, I would gather

 

If you ran 94's, remember they have power valves, so there's more to it than just jets.

 

Check float level too...

 

Don't not block off one carb on a two carb manifold. You will starve half your engine. Poor atomization. The manifold will not allow proper distribution.

 

I didn't think it was doable, that's why I hadn't done it, any ideas. I know the pwr vlvs don't kick in until over half throttle and my idle is way too rich, any ideas

 

Speedway carbs have a plastic float, they sometimes fill with gas and sink. I had this happen once with a 9super7 with very few miles on it and when I called Speedway they acted like it happens all the time. Almost caught my pickup on fire. Never again, I will only use the real deal. Genuine Stromberg's have a brass float and much better build quality. Sure they cost a bit more but you only have to buy them once and they work well out of the box.

 

There's now way around it, out of the box jetting will never get you right on the money with 97s, 94's, or any of the imitators.

Stark walking away from stock, and you can bet that you will be doing jet swapping and having to compomise.

For my 286 flathead, with two English Stromberg 97s on a slingshot, I ended up with .043" mains with stock #65 power valves. I'm at sea level, and am running a 270 cam and stock '42-48 crab ignition. Due to the flow limitations of a flathead, the middle cylinders read a bit rich, but the cylinders on the outer corners are right on the money. I can live with that.

 

Anybody got a good deal on a pair of English 97s

 

BTW blocking off one carb is not the answer. Small Flathead can use two 160 cfm carbs no problem. If you are rich its not the number of carbs it's the jets, the float level or your fuel pressure (float level also). I have two Genuine 97s on a 232ci flatty with 7:1 compression and a very slight cam (.350" 264 adv dur) and it runs fine at sea level and 3000' with the 45 jet that the carbs came with. 2 lbs fuel pressure.

 

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