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#1
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Dyno Help
On Friday I have a chassis dyno for one hour. What should I concentrate on first? Timing, jetting, carb spacers. I have never done this before but I want to be prepared. The motor is a 440 with 12.5:1 JE pistons Indy SRs full port/ polish. Comp Cams solid 632/650 lift cam. Harland sharp rockers 1.6 ratio. M1 single plane intake and Race Demon 975 carb.
Any help is greatly appreciated Thanks Bil |
#2
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Take:
A box of jets 4 hole 1" spacer 1 Hole 1" spacer Look in the bottom of the carb, do you have a brass jet in the center of the base plate? Where's you distributor set now...initial and total? |
#3
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Do as Cuda says! That thing outa be one bad Mother F'er hu? What numbers are you looking for? Make sure you post the results ASAP! Just curious on what rearend/gear and tranny combo your running?
__________________
68 Coronet 69 Super Bee......new 500 cid comin soon! 73 Duster witha missing 440/727 |
#4
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The tranny is a 727 with a manual valve body 8" 4500 stall Coan converter. Ford 9" with 4:33 gears. I will post info as soon as I get it.
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#5
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NICE COMBO!
Make sure you get the MPH/RPM numbers so you can check the convertor slippage. Did you look under that carb? Is it a new carb? Do you have it baselined? ...an hour goes by quick, be a Boy Scout..."Be Prepared" You may even need a King Demon on that monster. Record the manifold vacuum at WOT at the top end of the pull, it should read zero, if you have vacuum the carbs too small. I can't wait to see the numbers |
#6
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Thanks Cuda
I don't have a baseline. I am going to check out the carb tonight. I will have a friend with me to help. I will record the vacuum on the carb. Which port to I put the gauge on? |
#7
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Hey Cuda,
Just looked at the carb. I turned it over and did not see any kind of brass jet under it. Is it visible without removing the bottom plate? What is it? |
#8
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OK you don't have the King Demon, it's the Race Demon 4150 base.
On the King Demon's there is a jet in the center which is a circuit that they drilled to pull air into the the motor from above the throttle plates. You can drill or replace it with different size jets to add more air on the idle circuits...just another way of fine tuning a King Demon to get the max out of it. |
#9
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An hour sure does go fast on a dyno. The first full pull was 436.3 HP/452.5 TQ.
Second pull was 438HP/445.3TQ. Third pull was 445.1 HP/394 TQ. Fourth pull was 438.8 HP /475.2 TQ. |
#10
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So what did you do between pulls????
Numbers look dam good, I presume that was rear wheel numbers? |
#11
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Run #1 38* timing Stock jets 1/2 open spacer.
Run #2 Same but timing change to 35* Run #3 1" 4 hole spacer 35* timing Run #4 Same with 38* timing. My last run the A/F mixture was leaning out. I didn't have enough time to change jets. I don't know if this is true or not, But the guy that was operating the dyno said that my mph was not true to what my papers said. He said that due to the high stall, that the MPH would be off. I don't know how to find out my converter efficiency. These are rear wheel numbers. I hope i can get more out of the car. |
#12
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Quote:
Run #3 1" 4 hole spacer 35* timing See...See!! I keep telling you guy's 34-35* of timing and a 1" 4 hole is optimal for the average street strip, moderate compression, flat top piston Mopar......LOL Convertor efficiency test: Run it through the 1/4 mile and record your tach reading Then go to http://www.prestage.com/Car+Math/Gea...M/default.aspx This will give you the direct no slip RPM at the stripe based on your specs, the difference between what your tach read and the true RPM is the convertor slippage, it should be between 3.5 and 6% if it's a real good convertor. Anything over 8% and I'd sell it on Ebay...LOL |
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