Technical Dual Stromberg 97 tuning

I am about done in.

I have spent nearly two months trying to tune my Flathead so I can drive my 32.
It runs like shit. It idles fine and when you static rev it you get a lawn mower sound. On road it feels like it falls in a hole and has no power at all. I can milk it very slowly to the point where it feels like it might need second but is not pulling hard at all.

21 stud with PM-7 and 97s.

97s rebuilt over and over with parts from Uncle Max. I have rebuilt dozens of 97s and all is no different to any other car I've built for. Synced with Uni-Syn and both pulling same air. Has a tendency to die when snapped back from high revs.

37 -41 helmet distributor rebuilt and run on vintage timing fixture machine. New Skip coil, NGK plugs, Echlin condenser, new echlin points.

Fuel pressure steady at 2.5 psi but does drop slightly when it revs up (to about 1.5 psi). Confirmed fuel pump push rod is exactly right length to suit lift in thickstuns manifold (had to add length due to height difference of manifold). I have a new elec
Pump but want to try and solve the issue properly.

Valves are opening and closing properly and timing was set on machine. Advances as it should when revved.

I have read every thread I can find on HAMB and FordBarn and still runs like shit.

Before I go back to the stock manifold does anyone know what I have missed? This isn't my first flathead but I feel like it's amateur hour. Why can't I sort it?

 

Replaced fuel hoses and no change. Choke has no effect at all.

I'm completely baffled

 

Tried that route also. I'm convinced it's not distributor related as a result but stranger things have happened. I'm leaning towards a vacuum leak under intake. Spraying around edge and carb bases etc doesn't effect RPM though.

Cheers for the help

 

I was getting my car ready for ROG this year, rebuilt 2 97's, fired it up and it ran like shit! Pulled the carb multiple times just to check and re check......

You know what the problem was!!!!! I installed 2 used fuel inlet flare adapters.....you know, where the fuel line attaches.. There was a goddam mud dalber nest in one of them, completely blocked with mud!! I removed it, scraped out the mud and damn!

Are you getting fuel out of both accelerator pump discharge tubes?

 

Put a timing light on it to see if it's missing sparks. If the choke doesn'help it does not have a vacuum leak. Look down the throat of the carbs when you are running it and watch the spray pattern. It sound way rich, did you sinc you carbs? Gary

 

What do your plugs look like? Wet? White?

 

Fuel is flowing in a nice steady stream when engine off and atomising and flowing well when running.

Carbs are synced but it seems to have needed a lot of idle screw on both carbs to get it to idle without dying.

Plugs are from front to back - 1/5Sooty, 2/6coffee, 3/7barely sooty, 4/8slightly (and I mean barely) wet. I re synced again after and will check the plugs when I get back into it

 

It kinda sound like your not getting enough fuel, try turning your pressure up to 6 psi or higher...

Dunno what kind of reg ur using but I've had lots of issue with those spectre/ autozone round chrome ones.... Open it to all the way and put a pair of c- clamp vise grips orotund it depressing the knob....

 

I am using a spectre round POS. I have it wound right out to 5 psi and it still only reads 2.5 on gauge. I just got a low pressure Holley to replace it for when I put the elec pump in so might try swapping that in now. Stock pump with no reg should be about 3.5 psi right?

 

Check your pressure with a good gauge, those strombergs will not take 6lbs! I like 2.5 with mine.Gary

 

And be ready to turn it right back down if it comes squirting out the top vent! I've seen it happen.

 

Gauge is a big logo SW 15psi and have also tried one of those small gauges too (not liquid filled as I know they can be dodgy).

 

Any gauge can read wrong , try another. Gary

 

Just ran it with no reg and used two different gauges. Steady on 2.5 psi and drops not below 2 on full throttle.

Partial choke does speed up idle as it should but no change on road.

Good flow in carb when revved up but still wants to die after full throttle.

 

Man you have a tough one. I'd throw a single carb manifold on that thing and go from there. You've spent a lot of time doing everything else might as well try it. Sure would eliminate a lot
Have you tried a second condenser? Internal resisted coil on there or external?

Also it sure sounds like you understand a unisys but just trying to hit all bases. The linkage must be unhooked to properly adjust the carbs evenly.

 

From reading everything you've posted I'm sure (I hope) that the carbs have been meticulously cleaned, especially when you say that they've been rebuilt several times.
They are such simple carbs that the only thing I can make a suggestion on is the air bleed ports and jets.
Usually another sign of blocked air bleeds is that when the engine is shut off and it heat soaks the carbs will leak fuel into the venturis.
gbritnell

 

Give the engine some timing, it sounds like it is too retarded.

 

Is this a fresh motor rebuild or just a carb/intake change? If it's a new motor could it be a flat cam issue?

 

Put up a picture of your engine and intake , so we can see what your working with. Gary

 

Heres a picture of the engine and intake. Engine was pulled from a car getting a 350 and has been sitting in a buddy's shop for sometime. He does not know the history of the engine. It had no carb on it but a stock 34 Intake that I traded for this intake.

The air bleed jets and check valves are the only things I haven't changed out. Both had a good clean but look very second hand at the screwdriver slot. All
My spares look in similar condition. I'm on the road so best I can do for now. I will try some more advance when I get home tomorrow.

Thanks all for the help

 

I think I would put a block off plate under the rear carb and try it. I don't think that will work great permanently but will give you an idea were to start. Good luck, Gary

 

Tried that as well. And rotated the carbs and no change.

So that makes Me think both carbs, if doing the same thing as a single are at a similar state of tune. The only common item through all this is the intake. I guess I will see what advancing the timing does and if that fails I will pull the intake.

 

Have replaced the spark plugs as these days they seem to foul easly
What plug gap are you running?
I have found .018" to be best, any more than that and the terminals on the caps seem to start burning away on the Helmet style distributor.
Have you checked the float level, does it leak down if the motor sits for 1/2 hour?
What jet sizes are you running?
Have you also done a compresion test, as it is possible that it has a flat cam or maybe burnt or stuck valves?

 

Did you ever put a timing light and run it through it's RPM range, and see if the flashes are steady? Gary

 

Hello friend, I've haven't taken the time to read all your talkin about but sounds like the cam is out or backwards.from past experiences it will still run. Hope whatever it is works out for you.

 

I did run a timing light earlier in the piece but will do it again.

 

Spark plugs are new NGK gapped to .018 and jets are 43's with 69 pvalves. Compression test has all at or near 85.
Valves are opening and snapping shut in sequence.

Float level remains set.

I need to pull timing cover and check if gear is a fibre press on or not. Will it still run if it has jumped a tooth or worn teeth on fibre gear?