carb issues
I like to overfuel,and then back out.
-At 3000ft; I'ma guessing, your primaries might clean up with 74s, and you might have to bring the PV in a bit earlier. And secondaries maybe 80s. And the back might need an earlier or longer pumpshot.I would also check the T-port sync. When you run a lot of idle timing, it's easily possible to close the primaries too far, drying up the T-port, and destroying smooth tip-in, especially if the secondaries are cracked open too far.
-In my opinion, your timing is in too early. 35* at 2800 at 3000ft would not work well with a 4speed, and your cam/Scr. With an automatic and a 3000 stall; maybe. With a 3500TC; no biggie
So if you have a stick, I would let her buck to 28/30 at 2800, and then slow it right down to about 35* at 3600 . This requires a factory type 2-spring system; a light initial one and a stiff second one with a specially shaped hook.If you are running a Vacuum can, I would recommend to defeat it, until you get things working right.One thing atta time, else you will be running in circles.
-Personally I would also back off the initial at least 4* to 6*,but that's how I roll; it allows me to bring in a lot of vacuum advance at PT(part throttle), to smooth out that big cam.And it usually helps with the T-port sync.
-With the carb it's always a balancing act, between the carb and the timing.
I know dinking with the dizzy is a PITA; but when the timing is as right as it gets,everywhere, it's fabulous.
-As usual; a lot of reading and no "do this/do that", so here goes;
-Do this; Prove the fuel level is correct. Defeat the vacuum advance and defeat and block closed the secondaries. Install 72s or 74s as available.Set up or prove the T-port sync.(see below). Close the secondaries throttle to just short of sticking and then open it back up exactly 3/4 turn. Set the mixture screws to 1 turn out.Start 'er up and warm it up.When warm,back off the idle timing to 18 degrees. If the idle speed needschanging, use the secondary cracking screw, to get it close. Reset the mixture screws after the idle speed has been established.If the mixing screws end up being more than 2 to 2.5 turns out,close'em back up to 1.5 turns and reset the primary cracking screw, opening it 1/4 turn. Then resetthe idle speed with the secondary cracking screw.And finally fine-tune the mixture screws again. From this time forward always use the secondary cracking screw to change idle speed.
-Now, car parked;gently, open the throttle.If it hesitates reset the Accelerator pump to begin delivering fuel the very moment the throttle moves. There should be an instant stream.Again try it.
------------Setting the Transfer port sync;------------
Remove the carb, and safely empty it.Flip it over, making sure the throttle stays on the curb-idle screw. Eyeball the transfer slots, which reside at the front edges of the primary blades. They should appear as little squares, to slightly vertical rectangles; meaning taller than wide. If yours look like screwdriver slots laying flat, that is dead wrong.Either way, fix it with the curb-idle screw.While it's off, perform the other settings as in the previous paragraph.
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-Road test time. No,not floor it time.Next we need to prove the PV is synced up.You are gonna get into second gear and at least over 2000rpm, so 35 mph say.Now gently apply pedal to it in an ever-increasing amount, til you hit 45 or so, then back off and repeat, pressing harder and faster.You are checking the PV timing. If it comes in too late, the car will nose over as it runs out of fuel, and then,as the fuel starts flowing again,it will pick up and resume accelerating.This is often called a hesitation.If the PV comes in too early, it can be really hard to feel the engine go sluggish, but I can usually hear it in the exhaust pipe.This is especially true if the MJ is also fat. So try it with all kinds of different rates of pedal applications. This is a roll-into-it test, not a floor it till it blows up test. You can stop when you hit about 3500Rs.
-Next would be the primaryMJ tune. Once the PV timing has been established, you can start this.But heres the deal; the engine will need to be pulling a load, so first gear won't do it.You will want to start the test from around 3500 or a little higher and need to run it up to past the torque peak in second.You are also gonna want to put the power timing back in. You are gonna hit speeds approaching 80mph.So I ain't paying your speeding tickets.
-Ok then, if the engine goes lean she will tell you real quick, by nosing over at the top and perhaps bucking and farting if really lean.If she goes fat she will seem slow.That's why I like to start fat(no bucking) and swap til she complains, then go back up.See comments below to help with "fat"diagnostic. Lean can be diagnosed the same way.When it noses over, back out of the throttle about 10%. If it surges ahead, it was getting too much air for the fuel.
-To be sure there are other and better ways to do this test, but this way just costs time.So when you think it's right spend a couple of hours and days driving it, and making one change atta time, till you get it sharp.During this time, you can fool around with the part throttle timing, to discover if there really is something to be gained by working your way back up to the 22* that you formerly had.DO NOT adjust the idle speed screw.NOTE;Well, sometimes you have to, to get a better balance between idle and tip-in. But, if you do move it, memorize where you started from. And usually the change is very small.And usually you will have to reset the mixture screws. If the mixture screws are more than 2 turns out,then I would crack the primary blades up to 1/2 turn with the curb idle screw, and readjust the mixture screws. As the speed rises with increased timing,you will be using the secondary cracking screw to make idle speed changes.If you use the idle speed screw, you will mess up the T-port sync and have to start over with that bs;except as noted .
-During this time, I like to start with the vacuum advance tune. I would leave the 18* in it and start bringing in the can in as fast, and as much as possible, 'til it complains.But I get the feeling you are not a patient guy,so;
-Reset the power timing to max at 34 to 36*, hook up the secondary link, and IIRC you said it was a DP, so make sure it squirts as soon as the blades start to move. The PV is usually worth about 6 to 8 jet sizes so add 8 to whatever your primary MJs ended up being and slam those in there.Then tune them same as the primaries.Once the fueling is close, it's time to revisit the timings.
-You said your timings were 22 and 34. That indicates there is 12* in the weights.
I said start with 18 and, up to 36. So that makes 18 the estimated requirement.
Your driving results may now find 22/34 perfectly acceptable with the fueling bugged out. But if 18/36 works better, or 20/35, or 16/39, or whatever, works for your combo,then you will have to mod the dizzy to give the engine what she wants.Just don't try and force too much on her thinking that more is better, cuz it is not. In fact, for a streeter, a little not enough is almost without exception, better than a little too much.So don't be afraid to sneak up on the timing;at both ends, and in-between.Your engine will thank you for it,with a long and happy life. And your butt-dyno won't sense the difference of 2 or 3* not enough, but the engine will sure tell you about 2 or 3* too much!
Lesee, whadImiss?
Book-binding, I guess........sheesh