355 LE Dyno tune this Friday...Guess my numbers
#271
Be sure to do your Leak Down test when the engine is warm or you will get lower numbers due to less expansion (piston, ring end gaps, etc). If it is a bear to get to your plugs (like mine) then you can do it cold but you will notice a significantly greater amount of leakage.
Look for the largest variance. I don't like to see any more than 15% leakage between the highest and lowest readings.
Remove your oil filler cap, radiator cap, and air intake hose. You'll be listening for large amounts of air leakage from the oil filler cap, throttle body (open or it may divert to another cylinder with a closed throttle blade), and exhaust... you shouldn't hear much air... some is normal since no cylinder seals 100%. Bubbles would come from the radiator cap if there was a concern such as a cracked head, block, or gasket.
I'd also recommend removing all the plugs on the bank you are testing so you can listen to the adjacent cylinder for leakage... never know, but if the head gasket is compromised, then it will leak into that cylinder too. A stethoscope or a good diameter hose would be able to focus the sound from either of these test locations.
Look for the largest variance. I don't like to see any more than 15% leakage between the highest and lowest readings.
Remove your oil filler cap, radiator cap, and air intake hose. You'll be listening for large amounts of air leakage from the oil filler cap, throttle body (open or it may divert to another cylinder with a closed throttle blade), and exhaust... you shouldn't hear much air... some is normal since no cylinder seals 100%. Bubbles would come from the radiator cap if there was a concern such as a cracked head, block, or gasket.
I'd also recommend removing all the plugs on the bank you are testing so you can listen to the adjacent cylinder for leakage... never know, but if the head gasket is compromised, then it will leak into that cylinder too. A stethoscope or a good diameter hose would be able to focus the sound from either of these test locations.
#273
Wow. I hope its nothing like that. Considering that it makes 380 RWHP at 6K RPM then like a flick of the switch goes to hell above 6K RPM makes this less likely. But I can check a few cylinders anyway.
Current plan is to try 1.5 ratio rockers, then change the cam out if required. Tired of $#@!ing with it.
Current plan is to try 1.5 ratio rockers, then change the cam out if required. Tired of $#@!ing with it.
#274
![](http://forums.corvetteforum.com/photopost/direct_data/1124/medium/dyno_002.jpg)
#276
the 1.5 IMO will give you less lift but if you think the root of the problem is the ramp rate then I would say its going to do the same thing.
Would be nice if someone who is using the same cam could let you know exactly what they have done.
I know you have to be about fed up with it by now, Sorry
Would be nice if someone who is using the same cam could let you know exactly what they have done.
I know you have to be about fed up with it by now, Sorry
#277
The 1.5 ratio rockers will reduce lift and valve speed some. Hard to tell mathematically how much.
I am borrowing some 1.5 ratio rockers for test purposes, no out of pocket expense. This will move the lift into the 560's and much closer to the LE1 (w/ 1.6 rockers) cam. I will still have the fast ramps to contend with.
If this works and revs to 6.5K with no float then I will get new 1.5 ratio rockers and call it fixed. If float remains then the cam is coming out in favor of a LE1 or LE2 cam which appears to be much more proven.
Dickering around with springs is getting old.
I am borrowing some 1.5 ratio rockers for test purposes, no out of pocket expense. This will move the lift into the 560's and much closer to the LE1 (w/ 1.6 rockers) cam. I will still have the fast ramps to contend with.
If this works and revs to 6.5K with no float then I will get new 1.5 ratio rockers and call it fixed. If float remains then the cam is coming out in favor of a LE1 or LE2 cam which appears to be much more proven.
Dickering around with springs is getting old.
Last edited by wrd1972; 04-14-2008 at 06:08 PM.
#279
Much better cams out there. Isky has a sweet grind I ran for a while that does not tear up valvetrain, and Ed Iskenderian has been designing proven cams for a while.
#280
I hate to bump an old old thread, but does anyone know the rates or how to get ahold of phil at bluecat dyno? I have read on different sites that he is a great tuner but I dont know how to get up with him. Can anyone help me out here ?
#281
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