Intake Nozzles

Discussion in 'Manton Push Rods Top Alcohol Tech Questions' started by gt_diesel, Aug 10, 2009.

  1. gt_diesel

    gt_diesel New Member

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    I am in the process of doing the tune on my fuel system and had a quick question... The tuneup is pretty close, but I have a few stragglers... The car has 36's in the intake, 48's in the hat...

    The fattest cylinder has about half the cadmium burned off the face of the plug.. I have four cylinders with 3/4 of the cadmium burned off.. I have two that are burned into the 2nd thread, and one burned into the first thread.

    My thoughts were to change the nozzle jets to 38's in the 4 cylinders that are a little lean, to get them caught up to the others... Then lean out the main as needed to get them all fairly close to 3/4 burn.

    Will going from a 36 to a 38 be enough to go from two burned threads to 3/4 of a burned face.

    Timing is just about perfect... Main pill is a 120... Idle set at 6#, High Pressure set at 160#... No high speed bypass right now...

    Ran thru the traps at 7300 RPM, 186 MPH in a 2700 pound door car... Big Block Chevy
     
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  2. Mike Canter

    Mike Canter Top Dragster

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    Are all those plug readings after just one run on them?
     
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  3. gt_diesel

    gt_diesel New Member

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    Sort of.... We went to make one pass and had one of the bypass check valves stick open after the burn out so we had to go back to the pits... Fixed the check valve and make a pass then checked the plugs.

    Nothing was really lean, so we did end up making another pass with them after... Didnt see much change.
     
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  4. gt_diesel

    gt_diesel New Member

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    I have a bag of 42's and 44's... But figured they would be too much... If not, I can put them in the lean cylinders.
     
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  5. Mike Canter

    Mike Canter Top Dragster

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    Those two that are burned to the second thread have to be richen up. When you say "cadium burned off" do you mean that the flat base is dark gray or they have turned frosty? What was the cadium burn off on those two plugs that had heat to the second thread?
     
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  6. gt_diesel

    gt_diesel New Member

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    It might make a difference they are a hotter plug... NGK with a -7 heat range...

    I can probably take some pretty good pics of the plugs, but the plugs burned into the 2nd thread, the shine of the cadmium is gone and is kinda grey on the face... The ones that have partial cadmium on the face burned off are frosty.

    I had one of the Blown Alcohol guru's at the track take a look at the plugs as well.. He said it needed to be fattened up on 3 or 4 cylinders, but it wasnt bad enough to hurt anything.
     
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  7. SoDak

    SoDak Active Member

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    Going from 36 to 38's likely won't richen it enough, I would put the 42's in and try it.
    Figuring areas, adjust your main pill to compensate for the jet changes.
     
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  8. Mike Canter

    Mike Canter Top Dragster

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    Again, the heat range of a plug in an alcohol motor has no effect on the thread heat or the burning of the cadium on the flat thread base. It only changes the temperature of the porcelein around the center electrode. The only reason that you run the coldest plug is so the porcelein will not heat up and ignite the fuel like a glo plug. Why are you using -7 plugs to start with?

    You can't have half the cadium plating on the plug and half frosty because you are missing out a whole in between stage. The plug base can be half dark gray and half frosty. Why don't you take good high definition pictures of the plugs and email them to me at mike.c@mindspring.com. Keep the jpg file large so they don't blur. If you have to then send them in two emails. Name each picture as to what number cylinder.
     
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  9. gt_diesel

    gt_diesel New Member

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    The plug number goes along with the cylinder number.

    Plug 1..... As you can see, it is pretty dark on the face, color goes down into the plug 2 threads.
    [​IMG]


    Plug 2..... This one is a little rich, as you can see, only a little cadmium has burned off the face.
    [​IMG]

    Plug 3..... This is what I would like to see... Almost 3/4 of the cadmium burned off....
    [​IMG]

    Plug 4..... This one is similar to plug one... it has turned grey down into the 2nd thread... On a side note, it is not even, as it gets close to the electrode, the burning goes away.
    [​IMG]
     
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    Last edited: Aug 11, 2009
  10. gt_diesel

    gt_diesel New Member

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    Plug 5.... This one also seems a little fat....
    [​IMG]

    Plug 6.... Here are two seperate pictures, the face looks like it should with 3/4 of the cadmium burned off... But you can also see it is burned off into the threads some ( I am assuming that is just the way the plus is oriented in the combustion chamber.
    [​IMG]
    [​IMG]

    Plug 7....
    [​IMG]
     
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  11. gt_diesel

    gt_diesel New Member

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    Plug 8....
    [​IMG]




    here is one more pic so you can see the way the shine goes away on the threads.... This is also plug 8.

    [​IMG]
     
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  12. Mike Canter

    Mike Canter Top Dragster

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    Well I don't see what I would call burned threads two down. Tell me again which one you think it is. Also the motor is still running rich. Which one is what you call "frosty"? Try cleaning the plugs off with spray can of ether or brake cleaner and see how they look then. The ether or brake cleaner will clean off any oil or junk that could cause a false reading. Just don't wipe them with anything.
     
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  13. Comax Racing

    Comax Racing Member

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    Plug Question

    Again, the heat range of a plug in an alcohol motor has no effect on the thread heat or the burning of the cadium on the flat thread base. It only changes the temperature of the porcelein around the center electrode. The only reason that you run the coldest plug is so the porcelein will not heat up and ignite the fuel like a glo plug.

    Sorry to Hyjack this thread but I have a quick question on heat range. Keeping the quote in mind, if your tune-up is good, the difference between a -9 or -10 will not be that big of a difference? Then would the -10 be the best because it offers the least chance for detonation, is this correct?

    Thanks
     
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  14. SoDak

    SoDak Active Member

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    Mike, to my eyes I would call it burned down 2 threads in cyl #8. What do you called burned threads? Maybe you could post a pic of one of your burned threaded plugs?


    GT, what kind of heads/blower are you running?
     
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  15. gt_diesel

    gt_diesel New Member

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    It must have been the old ones that looked frosty... It had been two weeks since I had pulled them out. I guess what I was looking at, where the the plugs turned grey into the threads...

    I always thought that you were supposed to have 3/4 of the cadmium burned off on the face of the plugs, anything more than that was getting too lean.

    I am running the -7's because I only have a 7-al box and it seems to use the heat well.

    Where would you go with the nozzle jets... Would you leave them, richen a few up?

    When I made the pass that are one the plugs, it was like 90 degrees out. The next time I run, it will be in colder temps so I dont want to lean it out.

    Besides looking at the plugs, the car dosnt nose over, and it sounds good going down the track... No misfire or anything... Here is a link to a video of the pass.

    http://www.youtube.com/watch?v=3MHnbGSbnEg

    I broke a shock on that pass as well, but that is another story.
     
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  16. gt_diesel

    gt_diesel New Member

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    Canfield 350's aluminum heads... 14-71 Kuhl standard helix... 23 pounds of boost.
     
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  17. jim phillips

    jim phillips ta/fc

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    #8 looks leaner than the others make #8 look like the others then lean the main down its fat now for sure
     
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  18. Mike Canter

    Mike Canter Top Dragster

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    I have sent a couple of pictures of heated threads down to Two Threads and down to Four Threads. The big thing is that I don't believe you can put heat down two threads unless the plugs are frosty on the flat base first. GT's are not. When GT puts the pictures of mine up then compare and see what I mean.
     
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  19. jim phillips

    jim phillips ta/fc

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    mike i was not tring to counterdict what you were saying in no way to the plugs look fat and number 8 look leaner than the others thats all
     
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  20. gt_diesel

    gt_diesel New Member

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    Hey Mike, I have the pictures you sent me uploading right now... I will post them in a few minutes... I see what you mean about turning white, mine havnt got close to doing that.

    How would you reccomend changing my tuneup... I want to keep it as safe as possible... I just dont know if I like having such a big variation between the plugs. Also, with my run being made in 90 degree weather, would it still be fat enough to make passes in 60 degree weather?
     
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