Dyno sess.
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Dyno sess.

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    I'm No Expert Shaun's Avatar
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    Default Dyno sess.

    It's somthing i've been wanting to do, not just for the tuning but also because i really would like to know what the first motor i've built is puttin down. I called west tech and got some info/quote. It sounds like you rent out the room for the day, you bring whatever you want to test and they help you tune it.

    I'm wondering if i really am going to need a full day or if i'm going to be done way early and have just waisted $$ on the rest of the day. For you guys who have done this already, can you give me some advise on things i should do and bring. They told me anything i want to test i need to bring. My carbs are somthing i need to do some tuning on. I have a slight hickup when suddenly punching WOT. I had another thread open about this and we talked about shooter size and carb cams, etc. Do i need to now buy two cam kits, different shooter size's (or drill bit sizes), sets of jets, etc? Would rather not buy a bunch of stuff i may not need. Any since i have two carbs i'll need to buy two sets.

    Also, how do they monitor air/fuel ratio if my headers dont have a bung?

    I think tuning the carbs will be the major thing, other than timming what other types of things would i be doing?

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    Bring some oil and a fresh filter. You may want to dump the break in oil . Ask about the fuel they have on hand and see if it is what you normally run. Ask if they have jets and other carb tuning stuff, they probably do. They may have headers close to the same size you run with a bung already in place for the O2 sensor. The setup and clean up takes time.The whole day,8hrs,may seem like a long time now but once you get going, flys. I suggest you ask a friend that can turn a wrench to come along and do a good job of pitching in when clean up time comes around. Iam sure one of the guys that have dynoed at their facility will have info for you. Good Luck,DEL.

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    I'm No Expert Shaun's Avatar
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    Quote Originally Posted by DEL51 View Post
    Bring some oil and a fresh filter. You may want to dump the break in oil . Ask about the fuel they have on hand and see if it is what you normally run. Ask if they have jets and other carb tuning stuff, they probably do. They may have headers close to the same size you run with a bung already in place for the O2 sensor. The setup and clean up takes time.The whole day,8hrs,may seem like a long time now but once you get going, flys. I suggest you ask a friend that can turn a wrench to come along and do a good job of pitching in when clean up time comes around. Iam sure one of the guys that have dynoed at their facility will have info for you. Good Luck,DEL.
    Motors already broke in, ran it all season.

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    TRG
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    What did Steve tell you, do you have any other parts to try on your motor, that may benefit your power?
    If all you want to do is see where youare at Shaun?....go for a half day if its offered!
    You never know, a simple tune can be drastick! in a good way!
    Trust me when i say a carburator will make you or break your tune up!
    Ask Steve about my deal! lol
    Well worth the piece of mind in my opinion!

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    If you're going to have the dyno for a full 8 hours, you want to bring as much stuff as possible to try out, it would be very good to document what works on that motor. The tuning isn't going to take you long, with an A/F reading, timing, and carb tuning seems like a breeze. If you can bring every style of carb adapter you can, and different size carbs to play with. Maybe a different size of roller rockers to try, and of course an intake manifold would be nice to try. Of course all of this stuff takes money, hopefully you can borrow other friends parts. 8 hours is a whole lot of time in a dyno room, with an engine that has already proven to run well and doesn't have problems. Expect around 2 hours for tune time, and the other 6 is all for play....

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    I'm No Expert Shaun's Avatar
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    I'm some what expecting the tuning of the carbs to take alittle bit of time, i'm running 660's with a metering block conversion (4150's now). Dave over at DNE when i was having odd carb issues helped me out and tried to tune them alittle bit. I have a loop in my idle, he called it a hunt. He said these carbs are drag racing carbs and they are not really ment for cruising. He talked alot with me about everything, with i was recording that conversation. He talked about powervalves a bit (which i dont have) and how these differ from other carbs. Right now i have a hickup in it, i dont know what the cause of that is yet. If i put some play into my acc pump linkage the hickup isnt as bad. GN7 and some others where convinced it was a shooter size problem. GN7 was nice enough to send me out some shooters and a drill tool to test so i can see if a larger shooter is what i need. When dave tried to tune out the hunt i ended up with a non-responsive motor, it was lag bad. I have a feeling screwing with these carbs and attempting to get them right is going to be a task.

    Todd, they said i bring what i wanted to test and they would put it on and test, didnt sound like they had things for me to test but somthing like jets and cam's for the carbs i suppose they might. I'll call them back tomorrow and ask them a bit more about it. Peice of mind is right, i would like to make sure things are where they need to be, would really like to get the A/F ratio tuned too. I bet the shit of out this motor every evening i can when i'm out there so making sure i'm not running lean would be a good thing. Right now i'm pretty sure i'm a bit fat.

    Carb linkage, the mech 660's linkage activates the secondarys at a certian point of throttle, these carbs my dad got from a buddy, the guy i guess had filled the linkage alittle bit to delay the secondarys. Right now i want to say they dont start to engage till around 4K rpm. Is this somthing i should play with while there, seams like this might be more for economy, run a smaller jet in the primarys for better gas milage and then fatten it up on the sec side for all out?

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    I'm No Expert Shaun's Avatar
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    pw_tony, also i dont really have much stuff to test, most of my friend are not into this stuff and the ones who are dont have the money to be doing it.

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    A day on the dyno can go by pretty quickly if you're keeping busy.
    Basics first, IMO. Here's what I'd do.
    Fuel would be the first order of business. They have a set of dyno headers with EGT's and 02's to get your carbs dialed ins as close as possible. Problem is, they won't be the same headers you're running. Once tuned, you'll want to run your own headers and see what that does to your power. My typical Rewarder jet boat headers picked up significant power over the dyno headers. The tune can also be monitored with BSFC and other fuel factors once the dyno headers have been removed. If you have a gremlin in your carbs (which sounds like you may) you can use a lot of time chasing it around. If you have access to a KNOWN working pair of carbs, you might want to take them. It wouldn't be the first time a carb was flawed beyond tuning, and you'd like to be able to eliminate that as a possibility. If you do all you can within reason, and the problem still exists, bolt on the known good carbs and see what happens. If the problem goes away, you know what you have to do. If it persists, it may not be the carbs.
    Timing. You'll be able to find your best timing, but usually only after you have your tune dialed. Don't use timing to correct a bad tune.
    Oil pressure. Watch your oil pressure during a run, and go back and review the oil pressure read out. You may find fluctuations that you can settle down with changes in oil level or even try different oil. There is power in oil control. My 467 fluctuated more than 5 psi throughout a series of runs. By simply removing a quart, the pressure settled down to less than 2 psi fluctuation, and I believe we picked up some power.
    Cam timing/rocker ratios/lash. If you've got one of Chris' cams, talk to him about rr changes. Chances are, the cam's about as dialed as it's going to get. If you have the time, you can change cam timing, but that's time consuming unless you have a removable cover or belt drive. Again, if you installed the cam as instructed, it should be about optimum. This doesn't apply for a "guestimate" off the shelf grind. If that's the case, the sky's the limit, and you can try anything. More rocker ratio, change the timing, play with lash, etc, but that's going to burn up your day real quick.
    Scoop. Throw your scoop on there and see what it does for grins.

    One more thought on tuning the carbs. Keep it conservative. To net any measurable results, jet boats need more HP increase than you're going to get by tuning carbs to the last ragged HP. Most jet guys will find a reasonable tune on their engines, and you'll never see them touch the carbs throughout the year, unless the DA (density altitude) goes way in one direction or the other. There's just no performance return in a jet by picking up a few hp with jetting. Same with timing. Find where it's happy and leave it. If you can, tune your engine to what you think your typical conditions will be when you're at the lake or river. It's usually pretty hot in a dyno room, so the DA can be relatively high, especially if it's a a hot day outside. Take note of your dyno conditions and compare that to what you expect as normal conditions at the river or lake. If your actual conditions are drastically different, you'll have to think about compensating. Talk to your dyno operator about this and get his input. Remember, when you're comparing your power to your impeller, this is important info. The MEASURED power will be the actual power measured under the dyno room conditions, what ever they are. If the dyno room is 90* inside with w 40% humidity, the DA will be high...above 3000' most likely. The nice thing is, you'll probably have very similar conditions in the summer at the river or lake, so under those conditions, whatever the measured power on the dyno is can be very close to what your actual power will be at the river/lake. The CORRECTED power will be a calculated power based on a correction for the DA, since that can change from day to day, or even throughout a dyno session.
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  11. #9
    steelcomp was here
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    Quote Originally Posted by Shaun View Post
    I'm some what expecting the tuning of the carbs to take alittle bit of time, i'm running 660's with a metering block conversion (4150's now). Dave over at DNE when i was having odd carb issues helped me out and tried to tune them alittle bit. I have a loop in my idle, he called it a hunt. He said these carbs are drag racing carbs and they are not really ment for cruising. He talked alot with me about everything, with i was recording that conversation. He talked about powervalves a bit (which i dont have) and how these differ from other carbs. Right now i have a hickup in it, i dont know what the cause of that is yet. If i put some play into my acc pump linkage the hickup isnt as bad. GN7 and some others where convinced it was a shooter size problem. GN7 was nice enough to send me out some shooters and a drill tool to test so i can see if a larger shooter is what i need. When dave tried to tune out the hunt i ended up with a non-responsive motor, it was lag bad. I have a feeling screwing with these carbs and attempting to get them right is going to be a task.

    Todd, they said i bring what i wanted to test and they would put it on and test, didnt sound like they had things for me to test but somthing like jets and cam's for the carbs i suppose they might. I'll call them back tomorrow and ask them a bit more about it. Peice of mind is right, i would like to make sure things are where they need to be, would really like to get the A/F ratio tuned too. I bet the shit of out this motor every evening i can when i'm out there so making sure i'm not running lean would be a good thing. Right now i'm pretty sure i'm a bit fat.

    Carb linkage, the mech 660's linkage activates the secondarys at a certian point of throttle, these carbs my dad got from a buddy, the guy i guess had filled the linkage alittle bit to delay the secondarys. Right now i want to say they dont start to engage till around 4K rpm. Is this somthing i should play with while there, seams like this might be more for economy, run a smaller jet in the primarys for better gas milage and then fatten it up on the sec side for all out?
    Honestly, honestly, honestly....really sincere here...lose the 660's. You'll be headaches, time, frustration and performance and drivability ahead. You should be able to take a pair of 4777's or 4778's and bolt them on right out of the box and never look back.
    Or-make the 660's work. IF you can. I know...before I get flamed here, plenty have them that work flawlessly (or so they say) but I know plenty that have pulled their hair out trying, only to toss them in the garbage in the end. (I'm one of them) They were designed a LONG time ago with one very specific use in mind. Way outdated by today's stuff.
    JMO.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    Senior Member MACHINEHEAD1's Avatar
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    Steve is very very good at what he does. He will be able to load the engine with about 70-85 ft/lbs at idle like your jet pump in the water. Then you can whack the throttle as you do and be able to locate the problem. Usually there are some other guys down there that will be able to help you out. I know one personally that loves 660s ( Ken Crocie ) and will probably be there playing with his turbo Pontiac. I do think your buddy may have ruined them by cutting the throttle cam back. Your in good hands. The best IMO. Bring some extra cash for parts and clean your shit up or Brule' will bust your ass!

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    Great poats Steelcomp.

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    Quote Originally Posted by MACHINEHEAD1 View Post
    Steve is very very good at what he does. He will be able to load the engine with about 70-85 ft/lbs at idle like your jet pump in the water. Then you can whack the throttle as you do and be able to locate the problem. Usually there are some other guys down there that will be able to help you out. I know one personally that loves 660s ( Ken Crocie ) and will probably be there playing with his turbo Pontiac. I do think your buddy may have ruined them by cutting the throttle cam back. Your in good hands. The best IMO. Bring some extra cash for parts and clean your shit up or Brule' will bust your ass!
    +1 on Brule'. You won't find a better dyno operator, and he definitely knows engines. He's a good guy and will take very good care of you and your engine.
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.

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    I'm No Expert Shaun's Avatar
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    Steel, cam is from chris. Carbs were rebuild by bigs performance two years ago, they have worked well since then. Hickup started after i corrected a vacum leak and [email protected] tightened up the acc linkage. I started a whole thread about this a while back, i loosened back up the acc linkage and it has helped alot with the hickup. I'll try to find the old thread, might have some good info for you guys.

    Here's a video when the hickup was at it's worst, video is kind of dragged out, i dont nail the throttle until 25 ish seconds into the video.

    http://myspacetv.com/index.cfm?fusea...deoid=41017935

  16. #14
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    Quote Originally Posted by MACHINEHEAD1 View Post
    I do think your buddy may have ruined them by cutting the throttle cam back.
    Seams like that would only affect the RPM range between where they open now and where they used to open. I could find some stock plates i guess, i saw a adjustible linkage setup for sec's too in a jegs or summit catalog, not sure if it was for these carbs though.

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