BBC tuning problems, EGTS are way hot

Discussion in 'PSI Superchargers Tech Questions' started by alcohol altered, Aug 9, 2007.

  1. alcohol altered

    alcohol altered New Member

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    Can't figure out what's wrong: PLEASE HELP
    I have a blown BBC in an altered and recently burned up a couple pistons. After that ordeal I put in an EGT monitor. After I got everything back together I made a short 330' pass and played back the egts. They were at 1130 degrees at the 330' and at idle they were at 900. This setting was at 75% leakdown. I was told to put 85% in, I did that and the idle was in the upper 700's and as soon as it was reved up it went upper 900's. I figured my pump was bad so I sent it off and it flowed 12.2 gal at 123 psi (Enderle 110 pump). He said there was no problem with the pump. I went back to the track and tested with 85% leakdown and a 100 main with a 50 leanout set at 55 psi. The highest reading was 1100 on cyl 6 and the lowest was 923 cyl 8 )This again was at the 300 ft mark idled at average of 700 degrees. I came home and put a turn and a half in the barrel (almost 100% leakdown and it idled at 550 degrees). I then put the idle check to 12 psi with a 50 main with 85% leak down and the car idled at an average of 500 degrees and when slightly reved went to 700 degrees. I know the EGT monitor is right because the plugs were "fuzzy" after one 330' pass
    When I put in the new pistons the camshaft was never taken out. Before the leanout occured the spark plugs always looked new. And would run consistant 4.40's absolutely nothing was changed except pistons, rings, bearings and gaskets. While the heads were off a valve job was done. The car seems to be getting hotter and slower every time out.
    Here are the specs on engine. 496 bbc (4.50 bore 3.90 stroke), 11.5:1 compression,Pro Topline heads built by Jim Oddy, 8-71 HH delta opening 45% over driven (29 lbs boost) Enderle 110 pump, 8 number 50 jets in hat and lower 30's in port. Idle check at 6 psi, pump relief at 140 port check at 8psi main at 100, high speed 50 set at 55 psi. 32 degrees timing. Super Mag 3. Coan glide with Coan converter Car still went 1.03 60 (off .03 from earlier runs. and 3.03 at 330' off a little over a .10 from pre leanout)
    All lines have been pulled and checked, filter has been checked and cleaned. Any and all help would be great. I still think it's the pump.
     
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  2. jim phillips

    jim phillips ta/fc

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    you need to get the cylinders as close to the same as possible at the intake get the hottest down as close to same as the others putting more fuel to that hole the nozzels probably wont be the same in each port then your not going to burn any thing up i had a very similar combination the air plays a big part also get the motor happy first then you can play with main i would block the high speed till you all the holes close then play with the speed what kind of blower do you have this is important straight are a helix i dont think way off just need some fine tunning good luck ps the barrel valve schould be around 76% to 80% the main sounds close depending on the air you may need to raise pump relief pressure put more fuel in 6 raise the number 6nozzel
     
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    Last edited: Aug 9, 2007
  3. eli

    eli Banned

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    When you put a turn and a half in the barral valve, did you check to see if your valve went over center? theres a notch in the barral valve ,if that goes over center your actuly leaning the system instead of riching it as it closes off the hole the fuel goes true on wide open troddel, open the troddel and look at the notch on the barral valve where the arm to the turn buckel is, theres a little notch if it goes over 90 degrees its closeing up you can also verafy this by taking off the fuel line( assuming you have a K valve ) and look inside the barral valve, you will see a hole line up with the opaning of the barral valve I have seen this happen many times, every thing is fine till wide open then it goes lean. also make sure your arms on the hat and barral valve are on the same plane. :eek:
     
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    Last edited: Aug 10, 2007
  4. alcohol altered

    alcohol altered New Member

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    I run a Blower Shop blower high helix with all the seals. I have checked the barrel valve for over center (it is a K valve) and it is not. I just turned it a turn and a half at idle to make sure I could actually get raw fuel out of the pipes. I never ran it this way. You bring up another question on the cyl to cyl tuning. Can I still get the individual cylinders to cool down at idle when the port check is higher than the idle check? When it revs up the cylinder temps get alot closer.
    Thanks for the info keep it coming. I'm trying to go to the world fuel altered nationals.
     
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  5. eli

    eli Banned

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    Seems to me your trying to run this motor like it has a screw blower, lean down low and ports come in later,i always ran my roots rich down low and leand it out on the top end, i would get the ports working with the hat. and check your fuel tank maybe you picked up some crap off the track and it's blocking the vent. I love them alt. they were a trip back in the day with a 92 in. weel base.
     
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  6. TAFC 5 81

    TAFC 5 81 Member

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    Is this an iron or aluminum block and/ or head? Cragar intake? The combo sounds close to what I ran 28 years ago, but I ran everything in the hat. I had better luck w/ a lower (w/ a flat dome) domed piston (~10.5 to 1, 11 to 1 max) that seemed to produce a better "flame travel". Cylinders 2 and 4 were the traditional hot ones.
    I agree w/ eli, that thing would be happier fat on the low end.
     
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  7. alcohol altered

    alcohol altered New Member

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    It is a BDS competition manifold, Merlin pro race block, (cast iron) aluminum Pro Topline heads. What are most of you guys running for port check and idle check psi . The car ran fine for 3 years I bumped the boost up at the beginning of this year with no problems till the pistons melted. I ran the car several times with 75% leakdown 60 leanout set at 55 psi and a 115 in the main and showing 29-30 lbs of boost.
     
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  8. flatbladed

    flatbladed New Member

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    the tune up.

    we run a front motor car 477 chevy 11.7 comp. brodix heads 671 hh 34 lbs boost. 110 enderly pump.about the same area as you in nozzels.90 main. idle check 7lbs, port 20 lbs ,70% leak at the top of low gear my system makes 160 lbs of pressure. i have first highspeed open at 95 lbs with a 50 jet. the second opens at 125 with a 60 jet . I do not run a pump saver I have seen people go in circles because of these.we also use a racepack to record our runs. give me a call with any questions be glade to help. Jim a 651-335-7322
     
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  9. blubottleh8r

    blubottleh8r New Member

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    Couple good points have been made. TURN THE HI SPEED AROUND! It is a variable thing that you don't need in the mix right now. You can burn it up with the hi-speed later. Get it fat down low and ween fuel away from it down track later. If the thing starts off agressive and hot you can't cool it down later, you just buy parts. I would dissect every fitting, hose, poppet, nozzle, etc. If you haven't had it happen YET you'll shit when you realize how small of a piece of debris can destroy these things. Once you're sure that isn't the problem look again. Why? Just because. Work on evening up your cylinders and remember ever action has an equally costly reaction. IMO your ports seem small to me, but everyone has their own flavor. Best of luck
     
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  10. TAFC 5 81

    TAFC 5 81 Member

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    I agree with turning the hi- speed around (I had a manual hi-speed at times). When I went from iron heads (basic) to solid cast aluminum (d-ports), The engine needed to burn a whole lot more fuel and the blower became more critical. If the blower was bad it ran .2 slower than iron heads, but w/ a fresh blower, it was .2 quicker (a .4 swing). I ran quite a few 1/8 mile events w/o a hi-speed.
     
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  11. Relentless

    Relentless www.bretitanium.com

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    Does not seem like enough timing at all to me either...
    When we ran a Supermag II we ran between 39-42

    With all the other bits people have said if the motor is retarded then its gonna burn hotter.
     
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  12. jim phillips

    jim phillips ta/fc

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    do what his mag is hotter than that and you cant go as hi with the timing are you will burn it up if he IS not getting enough fuel to a couple of holes what ever you do get the holes cooled down that are two hot dont use the high speed untill you get things lined out then play with the high speed unless you have a lot of money because YOU WILL BURN SHIT UP BELIEVE ME when i started i didnt know shit about a blown motor the tinyest thing in a nozzel will cause you to burn a piston if its already to lean lean with to much timing burn a piston are head gasket MAKE THINGS SIMPLE STOP WHAT YOU DOING CHECK EVERYTHING THE SIMPLEST THINGS RUN OFF THE MAIN YOU FATTIN UP THE HOLES THAT ARE TO HOT IF YOU HAVE A 30 GO TO A 34 IF THERE TO COLD AND YOU HAVE A 30 GO TO A 28 IF YOU HAVE A MAG IV AND ITS HOT DAY 35 DEGREES OF TIMING IF ITS A COOL DAY 30 DEGREES SET THE BARREL VALE AT 78 PERCENT AND A 100 IN THE MAIN IT SHOULD GO RIGHT ON DOWN LEAVE THE HIGH SPEED FLIP SO IT WONT COME IN THIS SHOULD BE A SAFE TUNE UP IF YOU GET THE HOLES HALF WAY CLOSE ANY QUESTONS GIVE ME A CALL 812 303 9612
     
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    Last edited: Aug 10, 2007
  13. jim phillips

    jim phillips ta/fc

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    I THOUGHT THE NOZZELS WERE SMALL ALSO I WOULD GET THE HOLES CLOSE THEN RICHIN THEM ALL UP THEN YOU CAN LEAN IT WITH THE MAIN BEING RICH WONT HURT PARTS IT MAY FEEL LIKE A PIG BUT YOU AINT BUYING PISTONS
     
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  14. alcohol altered

    alcohol altered New Member

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    I am going to split the fuel difference from the hat to the ports (bigger port nozzles smaller hat nozzles) but keep the same total jet area. I will flip the high speed backwards, keep the timing at 32 and get the temps to even out on all cylinders. I will probably be able to test it out Wednesday as the track here is closed this Saturday because they are shooting an episode of Pinks. I'll let you know what happens.
     
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  15. jim phillips

    jim phillips ta/fc

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    I Just Thought Of This Check This To If You Have Rubber Lines One Are Two Of Them May Be Colapsing This Cause The Hose Suck Shut Cutting Of The Fuel Check Close At The Intake I Just Had To Replace Two On My Funny Car
     
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  16. trblmkr

    trblmkr New Member

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    Alcohol Altered just a couple things. Stay away from making wholesale changes to things. Your first post scares me cause it sounds like you are going about 10 directions at once (I’d be giddy if I were a piston salesman). Sounds like you had a tune up that worked at one time. What changed? Figure that out and go back to there so you can get the car to go a2b and not tear shit up. Then you can work on a faster tune up. Seen lots of guys have a car that goes a2b everytime and then the ‘hop it up’ in one big step (blower o/d, big HS, etc) and end up tearing junk all up. Then rather then going back to square one they take off on some nuttier-than-squirrel shit tune up and leave smoldering parts along the way. and they never find that baseline tune up again... they're lost

    Are you running 1/8 or ¼? JMO but for the most part you probably don’t have any business getting real aggressive with a basic HS before the 1/8 (basic system on a roots deal). if you are you better be careful going farther than 6 or 700 feet or that thing will be a torch.

    Go back to your baseline and get the car to repeat then make SMALL changes one at a time. No HS, not six shooters… no bullshit. Just get it to go a2b. get the thing where it will idle nice (leakin 70’s-80’s depending on idle) , with wet pipes, use the main only and set the timing where it has worked before 30-32 on BBC sounds good to me with a sm. Squirt it a few hundred feet and see what IT IS TELLING YOU. Adjust your main so it puts just a LITTLE color on the plug by 300 feet or so and then work on making them all look the same. After you get them all looking the same work on going farther. Get the thing where it will go to the 1/8 with all the plugs even THEN you can tune it. Again my opinion but i think you will find that without a HS the plug gets about as much heat as it is ever going to by the 1/8 but that is something to deal with after you get the thing a2b with all the parts still alive

    If I were to question one thing it would be the pump saver. You said it opens at 140? And you think your system is in the 120+ range? Where are you sending your pump saver? I would want those numbers farther apart like a 180+ pump saver. Just an idea
     
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  17. blown375

    blown375 New Member

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    One small question ,if you had the motor apart to replace pistons in it then all of the sudden the egts changed with only replacing some hurt parts. Are you sure that the camshaft is back in the correct position? Anyone can make a mistake and if the cam is in wrong that can have an adverse effect on exhaust temp and boost.
    Just a suggestion
     
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  18. jim phillips

    jim phillips ta/fc

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    well said, i talked to him earlier i think he is headed in the right dirrection with every ones help
     
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  19. TAFC 5 81

    TAFC 5 81 Member

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    Good idea, I had the timing off (way retarded) on mine at one pass and had flames out of the headers like a nitro car, but in reality it could not get out of its own way (.4 off in the 1/8 mile!).
     
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  20. nitrohawk

    nitrohawk New Member

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    This may not even be worty mentioning but might help. As I understand your situation you changed your combination up, burt pistons, then put egt's on.
    One problem is you have no prior reference for your egt readings on this motor. The egt readings can be effected by the distance of the placment from the cyl. and the distance they protrude into the pipe. If yours are not placed at the same place and distance as someone else with another motor then you will not get the same readings. Just food for thought. What is one guys ideal egt readings may not be the best for you! Another suggestion, always err on the rich side. Motors sound good when idleing lean but don't run worth a damm when the throttle is opened.
     
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