Throttle Stop!!!!
Frank
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| Jetting question for test and tune https://www.slantsix.org/forum/viewtopic.php?t=35916 |
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| Author: | Aggressive Ted [ Sat Jun 20, 2009 10:13 am ] |
| Post subject: | Jetting question for test and tune |
To Doctor Dodge and other fellow racers, Several folks on this forum have asked me to get a time slip for Doc's torque/mileage recipe with the 1920 Holley Economaster before I switch over to the Weiand four barrel intake and Holley 4360. They wanted me to compare before and after. I never put the peddle to the floor for normal driving so when I tried a few practice runs on a back road I noticed the car engine would cut out and surge at zero vacuum, but would go fine at 2 or 3" of vacuum. It will do it of the line, 30, 40, 60, or 90 mph. It really doesn't matter what rpm. Any ideas on what would be causing it? I was wondering if the dual plungers on the power valve might be interrupting the flow since they go in the holes so far. I could shim the power valve up a little so the forks don't go so far into the holes. I was running 16 degrees initial and 16 mechanical for 32 degrees total at 2500 rpm and at 3000 it showed 36 degrees. Josh suggested I back the initial down so I am at 12 degrees at the moment. The second question for test and tune, how large can I increase the jet? Any recommendations? I pulled the #57 and installed a #612 and it has allot more punch and mileage didn't change. Power output and engine heat sure went up to where I had to drop down to a 180 Super stat from the 195. I have 62H, 64 and 66 jets. How far can I go? I could buy a few more larger sizes. We are heading to the track July 11th so I don't have much time left. Thanks, |
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| Author: | emsvitil [ Sat Jun 20, 2009 12:20 pm ] |
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I'd T in a fuel pressure gauge (with long hose so you can read the gauge while driving) and see if you have fuel pressure when at WOT....... |
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| Author: | Aggressive Ted [ Sat Jun 20, 2009 12:21 pm ] |
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Done, it read 6 lbs. |
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| Author: | emsvitil [ Sat Jun 20, 2009 1:12 pm ] |
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Ok........ Weak/lack of spark (chinese plugs,wire resistance, old coil, large gap) |
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| Author: | Aggressive Ted [ Sat Jun 20, 2009 1:33 pm ] |
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Take a look at how the plugs are burning by clicking on the red link below my name. All less than two years old since engine break-in. MSD BLASTER 2 coil, as you can see in the pictures, 8mm wires all show low resistance, just replaced the cap with a CH410x Blue Streak and MO-3000 long tip rotor for general principle. Interesting thought about the coil though. You think it could be failing under load? Been running the NGK UR4 plugs the last two years gaped at .045. Running 10 volts at the coil at 600 rpm. |
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| Author: | emsvitil [ Sat Jun 20, 2009 2:17 pm ] |
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Easy enough to borrow a coil.......... |
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| Author: | 65Dodge100 [ Sat Jun 20, 2009 2:32 pm ] |
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| Author: | Aggressive Ted [ Sat Jun 20, 2009 2:49 pm ] |
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Yes, I have. It has a very health squirt and will spin the tires with a 2.76 posi-traction. Like I say putting it to the floor at zero vacuum is the only time the engine flutters or acts like it is cutting out. Backing off just a hair and hang on! Thanks! |
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| Author: | 66aCUDA [ Sun Jun 21, 2009 6:31 am ] |
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Throttle Stop!!!! Frank |
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| Author: | Dart270 [ Sun Jun 21, 2009 2:53 pm ] |
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I played with jets on the 1920 carb way back when, and it seemed like about 62 or 64, it did not get richer. Internal passages are then the limit. I'd try a 64 and see how it runs. Lou |
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| Author: | emsvitil [ Sun Jun 21, 2009 2:58 pm ] |
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It could be going tooo rich at WOT........... |
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| Author: | Aggressive Ted [ Sun Jun 21, 2009 5:46 pm ] |
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emsvitil, Quote: It could be going tooo rich at WOT...........
Is that really possible? With a 1920? Hmmm???....... I could put a small jet back in I guess and try it. :shrug: 
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| Author: | Valleyant [ Mon Jun 22, 2009 8:18 am ] |
| Post subject: | A suggestion |
Hi Ted, I have drag raced my share of rear wheel drive and front drive Mopars. I stage my Valiant with two feet. Left foot on the brake and right on the gas. Bring the car up on the convertor...I am at about 1600 RPM's and holding the car back with the brake for the take-off AND once I leave the starting line the throttle goes to the floor. Never do I go from closed to a fully open throttle on the drag strip. You need to juggle bringing the revs up, holding the car back and watching the lights for the take-off...Maybe this will cure the problem you are having....give it a try. Adjust your launch rpm's so you don't spin too much as it will hurt your elapsed time. If there is any skill needed for drag racing it's in the first 60 feet....you want to cover that distance as quickly as possible with the least amount wheel spin.....Good luck!, I am looking forward to the results! My '72 Valiant 225/auto 2.76 rear is running 17.8 to 17.9 at 75 MPH with the stock Holley One Barrel...running 57 jet, pertronix ignition and synthetic in the entire driveline...I empty out my trunk and pump the front tires to about 50psi for less roll resistance......nico |
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| Author: | Doc [ Mon Jun 22, 2009 11:30 am ] |
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It sounds like a lean condition at WOT... Richen it up as suggested... to see in you get a change. Holley Economasters were never known as being a carb that can flow a lot of fuel but if working correctly, it should flow enough fuel to provide correct mixture at WOT. May-be the float level is a little to low. Are there any other places where additional air can get into the intake manifold at WOT? PCV valve or EGR? DD |
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| Author: | Aggressive Ted [ Mon Jun 22, 2009 1:07 pm ] |
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Nico and Doc, Thanks for the tips. The EGR is blocked off as you can see from the pictures if you click on the red link below my name. I changed both carb base plate gaskets above and below the aluminum heat diverter just in case there was a leak. The PCV has a pretty tight rubber grommet and good hose tightened well. The intake manifold gasket seems to be sealing well. Take a look at the pictures. It idles nicely at temp. I will try a #62H and a #64 this week to see if it is just going too lean at WOT throttle position. The float height may be a hair low to keep it shut after shut off in this heat, but I wouldn't think I could empty the fuel bowl right off the line. I will try the to run up the throttle and let it go to see what happens. Normally I just punch it from idle and the accelerator pump shot is so strong it will kick her loose with the posi, then if I cram the throttle to the floor it will flutter or cut out slightly, then let up a little and hang on. Thanks for the tips to try this week. Maybe the Economaster is a little restrictive with that huge wagon wheel in the throat verse the slender "T" bar style 1920's. I will try an make it work. If not, at least I will have a base line for the 4360 Holley/Weiand setup. We went to the track (SIR/Pacific Raceway) this weekend and saw a few six second cars run at the LUCAS Oil shoot out. Yesterday afternoon they were rained out (hail, thunder and lightening) and closed early. At 9.5 to one compression is it worth going to higher octane fuel or just stick with the lower flash point regular 89 octane Cenex gas that comes with ethanol. |
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