engine stuff

Old 07-07-2007, 05:14 AM
  #101  
qtrmile2
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Carl,
Your getting there buddy just be patient. On my set up I have a 355 cu in with a 950 holley with 80 in the front and 82 in the back. It gets HOT in Missouri. The motor is a little fat in the heat but I'd rather keep it fat than lean. You have to be careful not to lean the motor out. Your running out of fuel could be the pump or a lean condition. What's your fuel pressure? Is it the same all the way down the track? I know it's hard to see when your moving. Look at your plugs that should tell you lean or fat. I also run 38 degree's timing with the advance locked down. Too much timing will also make the car seem likes it's running out of fuel. In any case without being there I would step up the jets and square the sizes front and rear to start. 80 front and 80 back. Go up 1 or 2 sizes until it slows down then back off 1. Just a few things to try.
If I'm not mistaken it sounds like your pump delivery. Are you running an air cleaner?
Keep me posted Carl :wink:
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Old 07-07-2007, 05:31 AM
  #102  
mcracecars
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107* hot and muggy is a bad air day.... :lol:
What happens is when these conditions are pressent, there is less oxygen in the air, and the water takes up a lot of room also, so the motor gets less oxygen to burn then on cooler less humid days...
IF you keep the jets the same the motor is running rich, as it still pulls the same fuel from the carbs, but now has less oxygen. Some guys make the mistake of jetting up in hopes of gaining et, /mph, but they only make it worse.
Ideally, you should lean the carb down to get the best mixture for the day for the best times/mph of the day.
You will never get the same power as on a good day, but you can get the best for the day at hand..
A simple density gauge can work wonders in plotting out conditions and jet changes over time, so after a while you can have a good idea of what you need for the day.
IF you keep an eye on what the prostock guys run all over the country, you will see that some places the run fast, otheres slower. Its all about track and weather conditions, altitude plays a big factor here too, and getting the car to make the best power for the location and conditions of the day.
You will never go as fast at denver as you will at gainsville....
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Old 07-07-2007, 08:21 AM
  #103  
bjuice
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Ed is correct and so was the lasts 2 guys..however you need to know that to get an accurate plug reading you must kill the car right after the pass and pull the plugs before you come back to pits..or get a tow back with car shut off..if the car is too lean at WOT...after you creep back to the pits the plugs will change causes inaccurate plug reading..

just a little tid-bit on that one..

i tell ya whats the best ivestment you can do..is the clamp on style EGT sensors..drill a 1/4 hole or smaller ( whatever the probe is) insert the probe into your header primary and use the cirlce clamp to hold it in place..( no welding required)...you can check exhaust temp gases from inside the cock pit and know where you stand at all times...most guys running alcohol use them ( BLOWN ALCHOL) paticulary..you can find these entire sets ups on e-bay pretty reasonable..

thnaks brian
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Old 07-07-2007, 09:58 AM
  #104  
chevguy65
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Here are a cpl pics of plugs, but after running it and pulled them this am.

It may or may not help.

Did I mention that during my first pass last night it was cutting out big time, engine temp was over 190.

I do not have a fuel press guage on it yet, and the fuel pump is mounted to high, it is above the rear axle, I know it needs to be lower and closer to the gas tank.
I am running 1/2" braided line from the tank to the regulator and then to the fuel log. Reg is set to 7 1/2 lbs.

I was also told to run two lines from the reg to the carb instead of a fuel log. Oh and the main line comes in on the back of the carb not the front.





Here is a pic of lines going to carb...
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Old 07-07-2007, 10:21 AM
  #105  
mcracecars
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you could also be getting some vapor lock in the fuel lines somewere or in the floatbowls. Fuel will flash into vapor at around 70 or 80 degrees, if I remember right.
Any fuel line close to hot pavement, over them heater hoses, or just a plain ol' very hot engine compartment can cause all kinds of head achs...
Hot days like that , you can chase your tail around looking in all the wrong places.
Try to insulate some fuel lines were they pass heat sorces.
On those kinds of days it is possible to be down 10% or more in power.
I am surprised both you and the car did as well as you did that day
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Old 07-07-2007, 03:03 PM
  #106  
chevguy65
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Thanks for the input Ed.
I do think it was vapor locking on my 1st pass, and I am surprised I braved the heat as well.

No A/C and after each pass I was soaked. I would park the car, start cooling it off and then I would go stand under the mister and drink about a gallon of water.
Funny thing is with all that water I never got full or had that sloshy feeling in my stomach.

Not near as many racers came out, usually we have 200-250 cars on a Friday night and last night it might have been 80.

Oh Drz1972ss, I forgot to mention I do have jet extensions on and on the 13.2 run my 60 was somewhere around a high 1.70 range. I accidently threw out the time slip so I am not positive.
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