Help with MSD D7 7531

Discussion in 'High Tech for Old Iron' started by chuck56, Jul 30, 2011.

  1. chuck56

    chuck56 Chuck Sincerbeaux

    Well... good luck with that... if it's not one thing it's another.... just want to make sure my carb is running rich enough.... I know Jim opened up your power valve a bit.... what size jets are you using?
     
  2. chuck56

    chuck56 Chuck Sincerbeaux

    I use C16 ... but not sure of the exact A/F... I think it's between 12 and 13 from the glance I made going down the track.....

    Jim....has a similar setup built by Jim Weiss.....Same supercharger and CSU carb ... but they drilled the power valve to richen it up a bit on the top end I think... just worried about detonation....
     
  3. offbrand Racing

    offbrand Racing Platinum Level Contributor

    Chuck,

    I would have to go back to our dyno sheets or pull the bowls but I know they where bigger than CSU supplied. We ran into a problem on the dyno w/ the AF ratio reading lean no matter how much jet we put in....I still think the dyno's fuel system was the problem as the pulls looks okay.

    If you want I can dig through my records on how the carb was delivered and what we end up with if you want.
     
  4. chuck56

    chuck56 Chuck Sincerbeaux

    If you have a chance that'd be great.. I think JW mentioned how big he drilled the power valve ... I'll have to find that post and check.... ...I know that Steve Morris talks a bunch in his dyno video about the importance of the fuel pump system when dynoing... I think he recommends using the one that you use in your car... as long as it is up to snuff .... apples to apples when you get the motor in the car...
     
  5. pmuller9

    pmuller9 Well-Known Member

    Chuck

    I just talked to the folks at Steve Morris engines and with the water to air intercooler and VP C16 fuel at 8 lbs of boost
    they recommended leaving the distributor locked at 30* and take out 4* final for a conservative start.
    They feel that you can work your way towards 30* if you want to be more aggressive
    A/F ratios should be between 11.5 to 12 and plug gap at .028

    On our twin turbo setups at 30 lbs of boost the A/F ratio is between 11 to 11.5 on VP C16 fuel.

    The car will probably run in the mid nines.
    Will that be a problem? LOL

    Paul
     
  6. chuck56

    chuck56 Chuck Sincerbeaux

    Great! I'm going to the computer in a bit and will plot the boost retard curve and will upload here!
     
  7. offbrand Racing

    offbrand Racing Platinum Level Contributor

    Chuck

    Kevin at csu had my carb set up w 74/83 jets which he said should have been right and what he has done for BBC w the v7 ysi. We ended up adjusting the pv and drilling pv channel, jetted up to 74 then 76 front and 87 rear but still ended up w 12.7 af. I will update you when I get it on the road and check af with my fuel system ( steve Morris suggested fuel system). I believe it will be pic rich in the car. On a side note I ended up w 34 degrees locked on pump fuel w water/meth which made more power than race fuel. All pulls where limited to 12 psi and 6 k rpm.

    I also think something else was not right during our sessions as the motor made within a few hp at 6k w 12 psi as it did with 17 psi. Haven't got an answer for that one but I have been thinking it had something to do w the 2' of pipe w had on the blower to mount one of the water/meth noddles.

    Hope that helps.

    Jim
     
  8. offbrand Racing

    offbrand Racing Platinum Level Contributor

    From your experience I have been thinking I need to plumb in an oil cooler with my filled block. I cannot image how much cooler my oil will be than yours. Ugh....just time and more money I guess. At least by the time I get all my new items installed it should be below 100 degrees.

    Jim
     
  9. chuck56

    chuck56 Chuck Sincerbeaux

    Hey Paul,
    Check out the curve. With the distributor locked at 30 degrees I added 8 pounds of boost to the 15. I then plotted a dot where 23 and 4 degrees of retard intersect and continued the slope.....Will sync the Cap and rotor with the crank at 26,,,,,, This should give me 26 degrees of timing at max boost.

    Let me know if this is ok to upload before I start asking more questions...
    Chuck
     

    Attached Files:

  10. pmuller9

    pmuller9 Well-Known Member

    Yep...That's it.

    Paul
     
  11. chuck56

    chuck56 Chuck Sincerbeaux

    Let me know how that works out.......If you plan on doing street driving and filling the block then the cooler may be the way to go... I think the aluminum block is the answer......with proper tune.... but that's a bundle....and still things break....it'd be nice to keep that temp down.....

    Also thanks so much for getting back to me with the specs on the carb...
    I have the Morris Video for tuning the CSU carb if you need it....I'm going to look at it in the morning....

    Can't wait to hear about your car going down the track..
    Chuck
     
  12. chuck56

    chuck56 Chuck Sincerbeaux

    OK time to upload! :Smarty: Chapter one...done...

    So if I want to get a bit more aggressive.... I would..... take out more timing?

    Lock in more timing .... then retard? Is there a formula? That would be too easy, I bet....

    Switches scheduled to arrive on Monday.... c

    Chuck
     
  13. pmuller9

    pmuller9 Well-Known Member

    Ok. Time for chapter two?

    If you want to get a bit more aggressive you would take out less timing 1 degree at a time.
    The 4 degree point on the graph would move up to 3 degrees changing the slope of the whole line.

    You can lock out more timing to see if it helps 1st gear then re-adjust the slope on the graph so your final timing is still the same.

    After installing the switches for gear indication you can experimemt with pulling 1 to 2 degrees back out in high gear by using the step inputs.

    Look at all the variables you get to play with.

    Then you can post all the results here for the rest of us to see.

    Paul
     
    Last edited: Aug 3, 2011
  14. pmuller9

    pmuller9 Well-Known Member

    I almost forgot. I posted this on the Boosted Buick thread

    It's alway good to know if the timing is right before you put the pressure to the engine.

    We use our leak down tester to check all our Racepak pressure sensors and any other pressure device.

    Make up a set of fittings so you can attach your 2 bar map sensor to your leak down tester.
    Don't forget to plug the hole in the intake manifold where the sensor was.

    With the regulator on the leak down tester turned completely off, start the engine and adjust the rpm somewhere above 2000 rpm.
    Then slowly apply pressure with the leak down tester till you get to 8 lbs and check the timing with a timing light.

    Let me know if this works for you.

    Paul
     
  15. chuck56

    chuck56 Chuck Sincerbeaux

    I made two passes today at the YellowBullet Nationals. Ran a 9.88 and then a 9.84. Little bit of spin on launch with drag radials. MPH was 110 at 1/8th and 131 at 1/4. Timing locked at 30 total.... The boost curve took out 6 degrees of timing...Foot braking..didn't use transbrake. C16. I go back out tomorrow for 1 qualifying pass in Pro Street and 1 in Pro Dial then Eliminations for both classes.... any changes?
     
  16. Skyhawk

    Skyhawk Well-Known Member

    Nice couple of runs Chuck. A little more seat time will make a BIG difference. Nice to see the car on yellowbullet
     
  17. chuck56

    chuck56 Chuck Sincerbeaux

    OK.....so I went to the YellowBullet nationals.....and made 9 passes....
    Best ET's were 9.84 @132 9.88@ 132 9.88 @136 and 9.91 @135 Shifting at 6,000 rpms.... throught the traps at 6000
    I took out 6* instead of 4* of timing by mistake.....memory issues I guess LOL
    Problem was I spun almost every time and had wheel hop.....I let off and got back in it.... Have QA1's in front..... Strange 9" locker 3.70.....HR Bar with adjustable arms.... 9" Drag Radial Slicks 20# air pressure.... Suggestions?
     

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