Idle EGT temps

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by Big Steve, Apr 3, 2018.

  1. swsc4133

    swsc4133 Member

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    With our combos, our idle side poppets are below 8. Again these setups are basic BBC, 8-71s and probably lower hp than what some of you are talking about.
    This is probably why the timing had an effect on the "surge". Like Mike said earlier it probably changes the idle enough to smooth it out.
    Big Steve our timing stayed locked at 32 to 36 depending on track and other factors. We don't run a grid.
     
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  2. SSDodge63

    SSDodge63 New Member

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    A long time student and reader. About 20 years back we ran BBC with 8,10 and finally 14-HH Retro with setback plate and Mallory SM-IV , timing 32-36 and had surging issues.
    Learned to use and set rpm about 2000 with a blade setting of 0.012, experiment.
    Then put a 100# pressure gauge from pump to BV and another in the port distribution block and started engine. Watched them cycle up and down with rpm and then started to move the idle poppet pressure setting up from a very light setting of say 3 pounds up to 10 or more. Looked to make the dist block pressure steady. Also pulled a port hose to convince myself that is was not opening during the surge which would put the AF all over the place.

    With a little heat in the motor from running, then set the engine for best throttle response. Then we would pull it into gear and found that about 2 flat richer on BV would smooth it right out. Recorded that BV reading and would always start the car with a weather change or OD pulley change and make sure the engine was at 2000 and best throttle response and then tickle the BV while in gear. When the BV was very sensitive, I needed to bump up the idle pressure. Like Will and Mike have said, once you find what your motor needs, it will become the baseline on how you should set it and the car will stage much better and consistent.
     
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  3. Ryan Van Dyk

    Ryan Van Dyk New Member

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    Hi Steve, Ive got a similar combo in my dragster here in Australia, its a rodeck BBC with big chief heads Wilson tunnel ram manifold and a mooneyham 14/71. Cam has .750 lift and 286/296 duration, 112 lobe separation. My barrel valve leaks at 80%, 10 psi idle check valve and 12psi at the port check valve. The car has run 4.13 to the eighth and 5.42 to the 1000' (havent had a full pass down the quarter with this combo yet) and the car is 2100 pound with a glide. I'm also getting idle temps up around the 1000 mark, I run 27 degrees of timing also, if I take anymore out of it the engine starts to hunt and gets a fluttery noise out the pipes as well as flames out of the pipes , I believe in my case and quite possibly yours too that the idle temps would go down with more timing.
     
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  4. Critical Mass

    Critical Mass Member

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    Hi Ryan,
    Your BV is too lean at 80%. That is why your idle temps are around 1000. What are your temps at the strap?
     
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  5. Ryan Van Dyk

    Ryan Van Dyk New Member

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    Strap or stripe?
     
    #45
  6. Dale H.

    Dale H. Member

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    I would set the butterfies at 10 to 12 thous. start it it up, have some one put it in gear and hold the brake, and adjust the barrel valve untill the surge goes away.

    -Dale
     
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