Idle EGT temps

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

  1. Mike Canter

    Mike Canter Top Dragster

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    With the engine at idle and surging watch the butterflies and see if they are moving and causing it. Try holding your fingers agains the butterflies and see if that helps with the surging
     
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  2. Big Steve

    Big Steve Member

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    I did exactly this today and was making good progress until I pissed off the neighbors. I guess running the engine 3 days in a row at dinner time was pushing my luck.
    Thanks for the tip, I think I am going in the right direction now, just need to keep tweaking it till its managable
     
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  3. Neil Morley

    Neil Morley Member

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    I think some guy get too hung up on leak down of the barrel valve while it's great to get you close your still gonna have to play with the BV usually to get the correct idle but definitely I believe the high idle EGTs are because your so rich and building a header fire , I too am running an XR-1 14/71 on a BBC and it's a very good blower and unless you don't plan on running much OD I question the 110 pump especially with such a large main jet, I run a 990 almost 3 home bigger than the 110 and I run a .95 main with 38%OD on a 555 ci and that blower makes over 40 lbs @8,000 rpm and I also agree you should drop your port check down to 6-8 psi and start with a 100 main, make sure your butterflies are set .009-.010" and adjust the barrel valve to get the correct idle and if you're convertor is tight sometimes it's harder to stop the surging in gear, good luck!
     
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  4. mogenss

    mogenss Member

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    I have not seen the fuel flow (flow meter) mentioned anywhere....

    The way I set my stuff is
    1) Set blade opening to 0.010 in
    2) Start with the idle fuel flow (0.75 Gal/min for my setup)
    3) Adjust the blade opening and BV to get to 1750 RPM @ 0.75 Gal/min

    Really care to much about the EGT at idle. If I idle it for a long time and the blades start to ice it will start to surge but otherwise it idles very smooth.
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    Since it was mentioned. Barrel Valve leakdown is used initially to put the idle adjustment in close proximity. Then you should abruptly crack the throttle and see if you have a rich blubber off idle or a lean hesitation. If adjusted so you have a quick responsive off idle response then do another leakdown taking note of the reading for your reference so if anything happens you can easily return to it. You should always try and use the same leakdown gauge and setup so it is repeatable. Different guages and setups will result in different readings so will different idle check valve spring settings so be careful of somebody telling you 82 is gospel. A setting of 8 lbs on the idle check valve requires a higher setting of the leakdown such as 85 whereas a 10 lbs setting may require setting it at 78. The idle check valve sets the fuel pressure at idle. Also the main jet is NOT in use while at idle. The idle fuel is controlled by the notch position in the spool of the barrel valve which position is changed when adjusting the rod between the BV and the blade throttle lever. The most used setup to do a BV leakdown is to disconnect the incoming and outgoing fuel hoses and the idle return hose and cap the idle check valve output. Some leave the output fuel hose connected but you are setting a reference for the BV and what flows through the hat nozzles is of no concern and doing it this way will result in your own numbers and not a percent number that is common to a percent number that somebody has that disconnects the BV output hose. It is not wrong doing it either way but just remember that leakdown percent number is your reference. It is important when checking the leakdown that you have a regulated air pressure of 100 psi and keep adjusting it to 100 psi during the adjustment.
     
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    Last edited: Apr 6, 2018
  6. Big Steve

    Big Steve Member

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    So whats your thought on Idle check pressure, Jim at Enderlie likes it low in the 5-6psi range, others like it in the 10-12 range
     
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  7. Mike Canter

    Mike Canter Top Dragster

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    I like them in the 8 1/2 to 10 region and that is the most common. I have never had a reason to be above 10 or below 8 1/2. Not saying that you can’t be above or below. I guess if the pump and setup can’t make and hold 8 1/2 lbs of fuel pressure then you need to heve it set lower. That idle check valve sets the idle fuel pressure at the BV so if you are above or below then it would result in different BV leakdown numbers. So if you had a 12 lbs check valve setting you would be down in the 70 percents on leakdown and if below 8 1/2 you would be higher in the 80 percents on leakdown. One thing you always have to remember is, if used, what your pump loop and high speed check valves are set at and that the idle fuel pressure is not opening and closing these check valves causing surging.
     
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    Last edited: Apr 6, 2018
  8. Will Hanna

    Will Hanna We put the 'inside' in Top Alcohol
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    Another thing that I have seen cause a surge - a very strong return spring. It was strong enough to flex the shaft against the stop and cause a cyclical flex/surge no matter what I did to the idle.

    Next time you take the hat off, drill and tap some 1/8 npt holes and install some 1/4" push fittings with plugs. If you really want to get fancy you can do a couple of 1/4 and a couple of 1/8 or 5/32, etc. Some even have dial gauges to adjust idle. This allows you to adjust idle without jacking with the linkage, which affects your BV setting.

    If you have a low idle check setting, and a high port check setting, the only place fuel can go through is the hat, so you're idling on the mixture going through the hat. As you can imagine, you will have hot holes at idle this way since you have very little control of distribution to the cylinders.

    Just remember heat makes it easier to detonate. Also remember it's WAAAY cheaper and easier to work from rich to lean than lean to rich.

    An MFI system is simple yet complex. It gets simpler as you understand it better, but there's a ton more to it than most people realize. I see so many racers try to get started by doing what so and so says. About the only way to learn is the hard way. By either running like shit or blowing shit up or both.

    As far as learning goes, I raced for a long time, tried a bunch of fuel system stuff before I finally gave in and started using Randy Anderson for all of my stuff. One of the best decisions I made in my racing career. Wish I had did it while I was still driving.

    Nothing against Jim at Enderle or other people who will give you an 'over the phone/pretty close' set up, but there is absolutely no substitute for properly setting up a fuel system on the flow bench. Experienced fuel system people like Randy Anderson, Jon Salemi and others know what fuel curve your application needs and have years of experience with various combinations. In most instances, you get the fuel system and it's pretty damn close out of the box. It idles right, runs right and doesn't blow shit up. Most will be more than happy to explain what everything is, why it is set up this way and why you don't do certain things.

    Some people will balk at $2000+ to flow a system when someone can get them close over the phone, then make a few runs to dial it in. Problem is you can't put a number on the money you don't spend.

    Mike Caro, a famous poker player, says "The money you don't lose spends just as easy as the money you win."
     
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  9. Big Steve

    Big Steve Member

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    Thanks Will for taking the time to make such an informative post. The push fittings is a great idea, in fact Steve Jr wants to install a metering valve we have to adjust the air inlet and take the pressure off the blades. It has also been suggested to drill and extra vent hole in the hat nozzle bodies and that may help with distribution a little, right now I am showing 0 pressure on the hat line after the BV because the lines are actually under a vacuum at idle with the blower sucking so much. I can get it to idle pretty smooth at 2200 then it goes to crap when put in gear. Working on getting a converter special built to address this issue, the one in the car is on loan, but did come out of a blown TD running 3.80 in the 1/8th

    As far as Randy goes, agree with you 100% on his knowledge, in fact I went to High School with Shelly, she was a couple of years behind me and remember when his Dad first started building heads and manifolds in his garage in the covina hills when I was hanging around the TA seen back in the early 80s. Problem is I would bet you 100 bucks I would still have the surge issue even if he flowed the system, without him having my blower, manifold and camshaft theres not way he would know how it would act at idle. He knows exactly what works and what dosent on the screw blown TAD TAFC and Pro mods stuff with his dads and AJ motors and I am sure he could make a huge difference in the overall learning curve for anyone like myself getting started with a blown alky combo and it is certainly not out of the question in the future to send him my system, but right now I got to get this surge under control so I can stage the car properly.
     
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  10. swsc4133

    swsc4133 Member

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    I'm curious, no one has mentioned what the timing is. From past experience we could eliminate the surge with just a few degrees of timing in our bbc's and sbc.
    Is this wrong? Could he maybe have a timing issue?
     
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  11. Big Steve

    Big Steve Member

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    27* currently
     
    #31
  12. Mike Canter

    Mike Canter Top Dragster

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    I don’t see how changing timing would stop surging unless the change in timing changed the idle rpm. If somebody can figure that out then please let me know
     
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  13. DR240

    DR240 New Member

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    I don't understand either but advancing the timing at idle helped the surge in our BBC. I put a grid on and have 38 deg at idle, then back to 30 over 2200rpm.
     
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  14. BEDNAR1320

    BEDNAR1320 Member

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    I have been watching this thread because Steve and I have the same blower and hat and very similar pumps and I also have the same surge problem, it's fine when it's not in gear, but as soon as I put it in gear it starts surging. I have tried almost every suggestion mentioned here (and more) with no luck. Steve and I have discussed this outside of this forum. Right now we are thinking that when it goes into gear that the converter drags the RPM down enough to slow the pump, which leans the engine then that speeds up the engine and it goes rich (or actually where it should be) and that slows it down and starts the vicious circle of lean, rich, lean, rich, etc. On my car the idle surges about 800 RPM in gear and the pump pressure (at the pump) goes from 17-32# while it's surging, I would think that has to be affecting idle mixture. I have the idle set at 2250 out of gear, I wish I could tell you how much it slows down when I put it in gear, but the surging starts as soon as I put it in gear. Best I can tell the RPM drops to about 1600 when I put it in gear, but like I said it's pretty hard to tell.

    Thoughts?
     
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  15. Mike Canter

    Mike Canter Top Dragster

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    You are correct on your lean to rich to lean statement. That is most likely what is happening. So you say your fuel pressure changes from 17 to 32# during the surge so what chack valves are set within that window that is opening and closing?
     
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  16. BEDNAR1320

    BEDNAR1320 Member

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    The idle check is at 10#, I have no high speed or pump loop. The port check is at 25# and pump saver is 130#
     
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  17. Mike Canter

    Mike Canter Top Dragster

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    Normally you want the port check under 15 lbs because the fuel pressure is way lower at that point but i dont think that is causing the problem. The launch would be more responsive at a lower pressure on the port. So what happens if you lower the idle rpm with it in neutral to the rpm that it is when in gear? Have you tried that?
     
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  18. BEDNAR1320

    BEDNAR1320 Member

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    I haven't tried that, Mike. I'm going to play around with it at the shop this weekend to see if I can cure it, or at least make it better. I will try that.
     
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  19. Big Steve

    Big Steve Member

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    A question I have is how do you know what the pressure is at idle between the BV and distribution block? I have a sensor at the pump reading about 19lbs at idle, the sensor after the barrel valve reads 0. Jim at Enderlie said it is because the hat lines are under a vacuum. Had a discussion today with Randy at RPM Performance the maker of my data logger about this. He said of course there is pressure there but it reads 0 because the sensor reads in PSIG which references atmospheric pressure which is 14.7 and being there is a vacuum in the hat it only will read 0 until the hat line is at 14.7 absolute pressure. unless you have a PSIA sensor which references 0 but your numbers would not match anything anyone is using for reference.
    So my question would be if you set the port check to a lower pressure, say 15 psi to add fuel to the ports to aid distribution how would you know if it is opening or not since you cant read the actual pressure at idle?
    I think a flow meter would be a huge help but at just over $1000 to add thats tuff at the moment.

    Like Brian said, I can make mine run clean around 2200 but as soon as you put it in gear it goes to crap, If I raise the idle to 2500, its a little better in gear but pulls thru the brakes when the surge goes up. I think the converter is key to this and am working with a couple of different converter builders to build a converter that slips like a clutch down low but locks up on top and I am told it it doable and hope to pull the trigger tomorrow.
     
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    Last edited: Apr 11, 2018
  20. Mike Canter

    Mike Canter Top Dragster

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    Steve you normally do not want fuel to the port nozzles at idle. One way they check this is by taking a port nozzle hose off and put in in something like a half gallon plastic milk jug and start the car up and see if you have flow or not.
     
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