1973 B3 Duster

Did you ever get that 340 tuned? I have A Hughes HEH3237 cam in my 68-360 FormulaS clone. Pretty much same spec cam as yours.TTI headers and 10.7C/R with aluminum heads. I will tell you what worked for me. After quite a bit of tuning, I can say this thing is almost too smooth.It idles so you know its in there, but almost like a stock 340. The trick is in the tune. Mine ended up with 12* initial, 22* centrifugal for a total of 34*. Then I put 22* more in the vacuum can for a total of 56* max.This may be a tad much for iron heads or a higher C/Rs or lower octane gas. Adjust the can as fast as the engine will accept without detonating.I started the mechanical advancing at 1200rpm and finished at 3400rpm. I used an O.E.M. distributor. I welded up the stops on the advance cam, and filed them out to what the engine wanted. I put 2 different springs in there.A fast soft one, and a stiffer slower one. This put a kink in the curve at about 2800rpm. I proved my TDC mark on the balancer and verified the rotor phasing. I would not use a "locked out" dizzy on the street.That Vacuum can makes the engine so much smoother in traffic.And better mpg, too. I have been using the same Orange box ECU for 14 years.I use the big Accel coil. These parts easily rev to 7000rpm,if your valvesprings do. I use those Champion copper plugs gapped at .045inch. Same plugs for 100,000 miles/14 years! Make sure your PCV system is working properly and that your engine has no intake leaks. Make sure your hot valve lash is correct.... There, that was the easy part. Next is the carb. Start and warm her up and set the idle speed to 800 rpm. Shut it off and yank the carb off and flip it over. Check how far the transfer slot is exposed.If the opening is between 1.5 and2 times as high as it is wide you are good,put it back on.If it is less than square she may stumble on take-off. If more than 2times, the exhaust tends to stink and burn your eyes.If its not in the ballpark,heres what to do; close all the throttles. Crack the secondaries just enough so they dont stick closed.Open the primaries just enough so that the transfer slots make a little rectangular opening, about twice as high as wide.Set your idle mixture screws as per factory. Holleys about 3/4 turn,Carters about 2.5 turns out. Now,put the carb back on and get it running.Keep it running.If you have to turn the speed screw faster, count the turns because you will eventually return to, or near to the previous setting. Now check/ adjust your float levels.Make sure your nozzles are not dripping. Make sure your power valve is not leaking.Make sure your fuel pressure is correct. Make sure your vacuum advance is not active and is correctly plumbed. OK so its running, warmed up, and nothing is leaking; fuel or air. Now, if you adjusted the idle speed you are going to have to return it to, or near to, the initial setting. This is how I do it. We need to know if the engine wants more air, or more fuel. Its almost always air it wants.Just gently restrict the airhorn with a rag.If it speeds up it wants less air.If it slows down, it wants more air. Simple.They always want air.There are several ways to give it air.I usually just drill a couple of holes in the throttle butterflies.How big? well..Trial and error. For this camshaft, I would start with 1/16 each primary, and work up to no more than 7/64 until it idles at a nice regular lope.Mine idles well at 800ish,with 5/64 holes.Readjust the mixture screws as may be required. If you go too big just solder those holes closed and start over.Heres another trick that I have used. Tee into the PCV hose at the back of the carb and install a jumper hose there. Find a wooden dowel that fits snugly in the hose. Drill a hole in the dowel about 3/32. Insert the dowel in the hose.Verify your initial idle speed adjustment and start her up.Need more idlespeed? Increase the hole size til you hit your target,adjusting the mix as may be reqd.Do not drill past 5/32 as this is about equivalent to 2 of 1/8 holes, and I believe that would be too big.If you cant reach your target at all, you can increase the idle speed screw 1/4 turn at a time, up to about a total of 1 turn.If the exposed transfer slot under the butterfly ends up being twice as high as wide,it is probably too far open and the idle circuit needs to be richened up.I havent seen that camshaft need it done. If your carb has idle circuits on the secondaries you can crack them open a bit too to see what happens.Still not there add 2 degrees of initial timing and start over on the primary side, from the beginning.Do not run more than about 16* initial,as the engine will get jumpy at slow speed in gear. When you reach your target, figure the area of the hole size,divide by 2, back-figure the equivalent area for each butterfly hole, and drill them.Do the math.You must use areas not drill sizes. This will get you started.Sometimes the float level wants to be readjusted; not often if parts are good.A good tuner with a parts stock could probably get you here in 2 to 3 hours. It took me 2 summers.I am tuned for E10/87 octane.120,000miles on it. If, IF you end up with the mixture screws open more than 2 turns on the Holley or 3.5 on a Carter, turn the speed screw in 1/4 turn faster and start over. If absolutely nothing makes her happy, I guess I would do a cylinder leak-down test and/or check the cam timing. I have run mine from 4* retarded to 4* advanced,and this method has always worked. Now the fun starts....Tuning the other circuits. Another time....Mine is a 4spd car too and with 3.55s. I can almost dump the clutch at idle and drive away.I can load it up, slipping the clutch and it will idle down to 600rpm. If I dont slip the clutch it gets a little jumpy like a 1st gen injected Mustang.That cam wont pull itself at idle in gear unless you slip it. It gets a little better if you retard the timing some,or reduce your cylinder pressure,but never goes away.For a time I was running over 200psi cylinder pressure.Very torquey. Very jumpy in gear at slow speeds. I cut it back to 185psi,much better.The jumpyness is also less bothersome with 4.30s in the back. Thats why this cam is about the biggest flat tappet cam in a 4spd car to run for most guys.I ran a 292/509 for a while. Not fun.I pulled it out and sold it to young guy with an automatic and a high stall convertor. I installed a diaphragm clutch. Easy on my left leg. Some Borg&Becks are murder in traffic or parades. I just realized how loong this story is. Ooops. First post. This worked for me, hope it helps you. I think I got it right.This cam doesnt really come alive until past 5000rpm. Mine pulls hard to past 7000.I love this cam.I had a Hughes He2430,which I liked more,until it lost 2 lobes from when they took the ZDDP out of the oil...... All the best to you and yours.........AJ is Going to bed now.I practically wrote a book......Oops,I might have posted here in the wrong thread, and being a newbee I dont have a clue how to move it.