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| Back on the road after car being down a week. https://slantsix.org/forum/viewtopic.php?t=36891 |
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| Author: | Aggressive Ted [ Sun Sep 20, 2009 4:45 pm ] |
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wjajr, Excellent documentation.....! Now you know what is going on... Quote: Do you think I need to install the black spring to keep the mechanical advance from kicking in before 1500?
What secondary spring are you running? I would try the black one since it would move everything over to the right about 350 to 400 rpm. It might just work with your mystery cam to settle the idle back down faster. Sounds like you got quite the race horse there..... Quote: Vacuum can is adding 4* at a too low 1200 rpm, so do I back it off a few more turns?
Yes, I would get it out of the picture to steady your idle.
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| Author: | wjajr [ Tue Sep 22, 2009 3:51 pm ] |
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Ted: Quote: What secondary spring are you running?
Green primary & big black long loop secondary spring which gives up last three degrees a little over 2800 rpm.The silver GM spring I used a few weeks ago before the MOPAR spring kit surfaced was a bit more stout than the new MOPAR green spring from the kit. I’m not pounding nails tomorrow (Wed.) at the new house, so most likely will dive into the distributor spring thing one more time. Hopefully this will be the solution I have been looking for all this time. Funny how easy these little projects are when viewed through Monday morning quarterback glasses. |
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| Author: | wjajr [ Wed Sep 23, 2009 1:14 pm ] |
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Hey Ted, I think that the jumping idle timing, and idle rpm hunting problem has been put to bed with the black primary spring. Today while recuperating from pounding too many nails at the new house in the last two days, I made the final distributor pull & spring swap after months of fiddling around to get this car to idle, and respond more calmly to low rpm throttle input. Many thanks to you for guiding me over each trial. To refresh everyone’s memory my 1967 225 ci. Dart is equipped as follows: A904 with shift kit standard manual-automatic valve body, and 2600 stall torque converter; 8 ¾ Suregrip 3:55 to 1; 1968 block, 0.030 over; 1977 peanut head shaved 0.075â€, over sized ENGNBLDR SS valves 1.70†int.& 1.44†ex. compression ratio 9.5:1, ported & gasket matched; Clifford intake & shorty headers feeding duel 2†exhaust w/ turbo sonic mufflers to the rear bunp’ah; Holley 8007 390 cfm 4V, primary throttle plates drilled w/ 3/32†; an unknown uppity hot cam possibly manufactured by Ernson; and electronic ignition, 11-R vacuum can backed off 4.75 turns, orange box, blaster 2 coil with their 8 ohm ballast resistor. I’m listing my findings below, hoprfully the data will be of help to someone. Initial timing set to +8 degrees; VC 208 (11R) vacuum can; 11-R governor: primary spring heavy mopar black from 8 spring kit sold by†bigslantsixfanâ€, secondary spring is heavy long loop. RPM………..Inch Hg………..Mech. Adv……….. W/Vac. Adv………Hg. w/ Vac Adv 850.lope……5-9 Quivering..8*…………….......8*……………….…...5-10.Q.Hg 900.lope……7.Q………………….8*………………....8*…………………….…8-9.Q.Hg 950Hunting…9.Q………………..8*………………....8*………………….…..8-9.Q.Hg 1000Hunting.9.5.Q………….…8*…………...…….8*…………………..….9-10.Q.Hg 1100Hunting.11.5 Steady….8*…………….…..9*……………………….11 Steady 1200Steady.11Hg……………...8*………………..16*……………………..12Hg 1300………….11Hg…………….…9.5*…………….18*……………………..13Hg 1400………….13Hg……………….10*……………..19*……………………..14Hg 1500………….13.5…………………12*……………..20*……………………..14Hg 1600………….14Hg……………….14*……………..23*………………………14Hg 1700………….15Hg……………….20*……………..25*………………………14.5Hg 1800………….15Hg……………….20*……………..28*………………………15Hg 2000………….15.Hg……….…….23*……………..48*………………………16Hg 2200………….15.5Hg……………23*……………..48*……………………….17Hg 2400………….16Hg……………….25*……………..50*………………………17.5Hg 2600………….16Hg……………….25*………………51*………………………18Hg 2800………….17Hg……………….25*………………51*………………………18Hg 3000………….18Hg……………….25*………………51*………………………18Hg In gear Idle: 550 bad lope…0-4.QHg………8*………………..8*……………………….0-4Q.Hg Current idle is set @ 950 in “Pâ€, yielding an in gear lopping rpm of 600 with throttle plates closed at zero idle speed adjustment. This is necessary to limit light throttle response flat spot. Hard acceleration manifests slight bock, but has very short duration. I noticed that fuel consumption was a bit excessive while gathering the above data. There was a lot of low rpm idling with low erratic vacuum readings. I wonder if my 3.5 power valve was enriching unnecessarily during this process. Just test drove about 20 miles. Engine is not particularly punchy, perhaps a bit doggy off the line. Starts to pull hard past 3000 rpm. So-so 2000 to 3000 rpm. If the vacuum can adjustment were to be turned in a few turns would that increase low rpm pep by cranking in a few more degrees of advance sooner? I guess this cam is tuned for 1000 rpm idle, power 3000 to 4500 rpm. I don't pull her past 4500 rpm, as I have no clue as to what a reasonable safe red line would be. |
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| Author: | Aggressive Ted [ Wed Sep 23, 2009 6:10 pm ] |
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wjajr, I love happy endings!  Good documentation. Now you know what is going on and can easily fine tune the pod. Since you have the black spring on the primary to keep the weights from popping out to soon, I think you could get away with 3 turns on the pod. If not, maybe try 12 degrees base timing. The slant likes lots of advance early (30 degrees before 2000 rpm) which gives it a punchy feel. |
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| Author: | rock [ Wed Sep 23, 2009 6:56 pm ] |
| Post subject: | wjajar, thanks for the data, did you find this thread too? |
wj, I have been enjoying this thread because I am one of the tuning nuts here. I knew Ted could do you just fine and he did. A while back I posted a list of all the available cans and the ranges of vac. they come in at when adjusted from all in to all out. That data is close to this this thread, which I wonder if you also found? http://www.slantsix.org/forum/viewtopic ... sc&start=0 Tables of data like your last table are good additions to Emsvitl's curves and that series of posts, too. rock '64d100 |
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| Author: | wjajr [ Thu Sep 24, 2009 3:35 pm ] |
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Thanks Rock for the hot link. A lot of good stuff there, and much easer to understand what everyone is describing now that I have been jumping through the tuning hoops. Had I read this information before all the experimenting, non of it would have made any sense, and caused excessive confusion. |
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| Author: | Aggressive Ted [ Fri Sep 25, 2009 9:33 am ] |
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wjajr, Quote: Engine is not particularly punchy, perhaps a bit doggy off the line. Starts to pull hard past 3000 rpm. So-so 2000 to 3000 rpm.
Your hot mystery cam has allot to do with the lack of line punch. As you stated your cam comes on at higher rpms, and that sacrifices low end punch. On the other hand my E254 cam has lots of low end punch and tapers off at the higher rpms.All you can do is balance the engine out (given your running gear) to meet your needs the best you can, which you have done. Each step corrected/tuned a specific variable. If you were a racer and had a stick the outcome would be totally different. Since your not racing, you have managed to tame the cam to make your car drivable on the street with acceptable performance. |
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| Author: | wjajr [ Sat Sep 26, 2009 10:53 am ] |
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The test drive at +8* was returning dismal fuel mileage for what ever reason. All most a quarter of a tank (first ¼ ) in about 40 miles. Granted there was a lot of WOT from dead stops, and 40 to 70 spurts to get the feel of the +8* setting. Using the poor man’s dyno (PMD)I was unable to achieve any wheel spin form a stop power braking. I have since swapped out the white (lightest) secondary vacuum spring for the brown (second to stiffest) spring to keep the secondary throttle plates closed below 2800 rpm, my 55 mph cruse rpm. Today I had a chance to mess with intial timing a bit. I upped the + 8* to +11* which provides a lot more punch of the line, as well as stronger pulling in the passing speed range; 45 to 80 mph. Today a second pull on my PMD indicated that the three degree increase in initial timing provides more low end torque, as twin black strips were applied to the pavement. I’m going to run this setting for a while and see how fuel mileage sugars out. Second test setting will be to screw in vacuum can adjustment 1 3/4th turns for a total of three, and back down initial timing to +10* as the floating idle rpm has returned. |
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| Author: | Aggressive Ted [ Sat Sep 26, 2009 12:00 pm ] |
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wjajr, Quote:
The slant likes lots of advance early (30 degrees before or at 2000 rpm) which gives it a punchy feel.
This is a key point that you are proving to be true with your latest adjustments.A few degrees initially really make a huge difference in the SL6. Since your distributor springs are set to handle the cam to achieve a consistent idle, you have two other areas to make up the difference. Your initial base timing and the vacuum pod. Keep at it.......as it is a fine balance at this point. |
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| Author: | wjajr [ Sat Sep 26, 2009 12:16 pm ] |
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I couldn’t wait for another tank of gas to flow through the old Holley, and just reset timing to +10*, down one degree from this noon’s adjustment, and cranked in the vacuum pod 1 3/4th turns for a total of three. Vacuum advance kicks in at steady throttle rpm of about 1800 rpm, and mechanical advance timing is creeping in at 1500 rpm, and all in but the last three degrees by 1700 rpm. Engine still pulls hard. I suspect that if the torque converter stall was up around 3000 rpm instead of 2600 (for a V8) I could roast the rear tires. As things are now she just hooks up too soon to take advantage of full torque out-put. Oh well… At least the car is much more pleasant to drive, less harsh, and now has a controlled idle where she will sit in traffic (like we have any traffic around here, two lights half mile apart in a county half the size of Connecticut) idling with one foot on the brake, none on the gas. With the timing back up, the exhaust note at idle is a bit louder and more staccato. I guess it makes a statement under 1000 rpm to some folks; 340. I just love telling them that it is not a 340, at which point they swing both ways 273 or 383… |
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| Author: | wjajr [ Sun Sep 27, 2009 1:15 pm ] |
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Just went on a 190 mile round trip to a car show. Tachometer was parked at 2800 to 3000 rpm 95% of the way. Engine pulled real strong, settled down to a nice idle when we reached our destination, and returned 18.4 mpg. I can live with that. In contrast, one of the guys from our parts took his 440 Road Runner 4 speed to the show, and destroyed almost twice the hydrocarbons that the slant did. |
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| Author: | Aggressive Ted [ Sun Sep 27, 2009 8:01 pm ] |
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Wjajr, That is not too bad on mileage, you may have to put a stiffer spring on the secondaries.... 2800-3000 rpm is how fast in mph? Glad it is behaving at idle and has reasonable punch given the torque converter not quite matching your cam. |
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| Author: | wjajr [ Mon Sep 28, 2009 3:34 am ] |
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Ted, Changed out white spring for brown secondary spring (second heaviest) on Friday. I did noticed that most of the flat spot at speed disappeared after the spring change, I think, indicating that those secondary throttle plates are staying closed higher up the rpm band. 2800 rpm is around 60 mph. When I first started driving the car last year before making any adjustments with timing & carburetor I got 20 mpg on one test tank (only fuel mileage test made). In those days I did not drive the car over 55 mph as it was a creaking mess suspension wise. It also was not nearly as punchy, and willing to pull, but a dog. |
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