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Discussion Starter #1
Have a 68 Camaro bracket car, 3400 pounds, 540 BBC, last year running without the bottle it went 6.30 in the 1/8, with a 150-175 shot on the bottle went 5.70. Over the winter it was pulled apart to do some mild porting on the heads and intake, only other change was a new tranny but kept the same converter. Take it out this past weekend for some testing and this thing just won't run, almost 2 tenths slower without the bottle and putting the bottle on it it just dosen't pick up much at all. Could there be something in the tranny with pump pressure not letting the converter flash like it did last year? Just seems like it won't flash the converter at all and just drives out.
Thanks in advance for any comments and suggestions.
Derek
 

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Have a 68 Camaro bracket car, 3400 pounds, 540 BBC, last year running without the bottle it went 6.30 in the 1/8, with a 150-175 shot on the bottle went 5.70. Over the winter it was pulled apart to do some mild porting on the heads and intake, only other change was a new tranny but kept the same converter. Take it out this past weekend for some testing and this thing just won't run, almost 2 tenths slower without the bottle and putting the bottle on it it just dosen't pick up much at all. Could there be something in the tranny with pump pressure not letting the converter flash like it did last year? Just seems like it won't flash the converter at all and just drives out.
Thanks in advance for any comments and suggestions.
Derek
I have seen one powerglide, done professionally, under perform another, done locally by two tenths. Put the other back in, and back to the original ET. Also, the converter may need rebuilt. It only takes one run, and it’s shot. And you don’t really know why. Seen that also. And the car slows considerably. It still stalls up, but it’s shot. And I ain’t no automatic expert.
 

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Discussion Starter #3
The converter was flawless and worked great last year with not a single hiccup and it goes south on the first hit this year?
 

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I don’t know, but yes, I’ve seen just that happen. Not saying that’s the problem, but it could be.
x2

had one person i know run a couple seasons with the same trans and first hit the following season bitch said not today junior
 

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Discussion Starter #8
The car doesn't have a racepak but I pulled the data from the grid and it doesn't matter on or off the bottle it's struggling to build rpm coming off the trans brake. 1.85 seconds after trans brake release it only picked up 1100 rpm. And the difference from on and off the bottle is only a tenth, that's with a IS dual crossbar plate with 51 nitrous jets and 36 fuel jets which is actually a bit more than it got sprayed last year when it went from 6.30 down to 5.70 on the bottle.
 

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Also, look at what you changed. Trans mainly. Heads, possibly, but I very much doubt that’s it. Have you installed a new crank trigger? When they go bad, they just go bad right now. And they will slow your ass down.
 

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Discussion Starter #13
I was thinking that the porting may have moved the power a bit and we did change launch rpm up and down by up to 800 rpm with very little change from highest to lowest. When the bottle was on we also changed the controller from 40% at the hit all the way to 70% at the hit and again very little change and what change we did see was down track and it just seems that nothing we did helps it do anything other than drive out of the hole where as last year it launched hard even without the bottle.
 

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Discussion Starter #14
I agree that the porting could have changed where the power is but I have a hard time thinking that it killed it 2 tenths in the 1/8 and nothing seems to change that. Higher or lower rpm, nitrous or no nitrous, 40% to 70%. All that and just no significant change. Am I missing something?
 

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No way the heads are the problem. I thought about this, and come on guys, if a reputable porter did them, somewhere on that track he’d feel the new found power kick him in the ass. They didn’t move the power band up much at all with mild Porting. Should have helped it. But, I’ve been wrong before. Whatever it is, it’s simple, I’d bet.
 

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Discussion Starter #16
I'm thinking along the same lines as you Randy. The porting increased the flow on the bench a total of 35 cfm and if it were in the heads the changes we made to launch and shift rpm when testing would have showed change.
 

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Check the trans fluid to see if anything looks wrong. If not the only other choice is the heads. I can tell you it’s a whole lot easier to slow one down than making it go faster. Do a leak down and see what is happening.
 

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Discussion Starter #18
Tranny fluid looks great, no burn, no metal, 3 passes in just over an hour and it didn't get any more temp than 160 degrees
 

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Well if it was mine (and it’s not) I’d check all the usual
stuff like making sure the carb is going wfo, ck the timing & make sure of TDC along with a quick ck to see if the cam is in right, disconnect any timing retards ,use fresh fuel etc.

Any chips would be suspect if you’re running any.

Then I’d ck the line pressure

If all that cks out, out with the converter!
 

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Discussion Starter #20
No chips to check, it has a digital 7 box with a grid controlling it. Timing, cam, tdc, wide open throttle etc is all good and double checked, checking the timing on the grid data it's all good and doing what it should be. Check line pressure tonight.
 
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