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Discussion Starter · #1 ·
I was having some fun with an 2001 cobra tonight, we raced 3 times. he got me off the line every time but I kept up with him. I have a weird hesitation on the 1-2 shift. I was not powershifting but shifting from 1-2 I would let off the gas and as soon as let off the clutch and punch the gas the motor hesitates for split second and and then goes like normal

I had the shift light set at 5800 and I would het the rev limiter at 6k which killed me on the first 2 runs. On the 3rd run I set it the light at 5600 so I wouldn't hit the limiter but the car still hesitated when I punched the gas in second.

I don't think I hit the limiter, it's almost seems like a carb prob, maybe too rich but this carb never did this on my 289 and I did not make any changes when I went to the 302. It's like the motor goes dead for a split second then regains.

I'm gonna put the 7k chip in the msd to avoid hitting the limiter but if the hesitation is still there what could this be?

It doesn't make sense to me that this would be a carb prob though cause in first gear the car goes as soon as I slam the gas with no hesitations at all.
 

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Verify that the accelerator pump(s?) have a nice steady stream. You may want to play with pump cams, assuming you have a Holley (or similiar.)

What is your total timing set at with no vacuum advance?
 

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Mechanical Secondaries? Your carb maybe fine. If it was all set up the way you liked, then moved it to a different motor, it probably still is fine. Shooters could be a problem though....

Do you have a vacuum canister hooked up to your dizzy?

If so, disconnect it ( and plug the vacuum leak) next time you race. You may find that when you let off the gas, vacuum increases above 10 HG it is advancing the dizzy past where you would want it then as soon as you go WOT again, the vacuum drops under 10 HG and the dizzy is pulling back to where it should be, but the result is a momentary hesitation where your dizzy is getting back to where you want to make power.

I installed a switch and solinoid to take my vacuum can out for racing.
 

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Discussion Starter · #4 ·
Yes this is a 650 DP with mechanical secondaries, I don't have vacuum advance so that can't be the cause. My initial timing is set at 14 degrees and total timing is at 32 currently.
 

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Man your killing me, what was your track times, I assume this was at a track? I had the same excat issue w/ the 65. At the time I was running a Holley 600 vs that had been on it for over 10yrs. No matter what gear I shifted into as soon as I got back on the gas it was like a very small dead spot then would go fine. I just final replaced the carb w/ a 600 dp I had rebuilt and no more issues. I think it was the accelarator pump though...
 

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Discussion Starter · #6 ·
no, not at the track, but on a closed course. What you are describing is exactly what is happening but Im not noticing it in on the 2-3 or 3-4 shift. I just put the 7k chip in so I'm gonna go try it again and see what happens. It is possible I was still touching the limiter since the car is geared so low in first. I will post an update when I get back
 

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Discussion Starter · #7 ·
Well, I just took the car out and the dead spot is gone, I did change the chip to 7k but other than that the only thing different was the car running cooler than last night, I don't know that having the car running hotter would make that much of a difference. Both squirters are working like they should; primary is a .031, secondary a .035. Maybe the rev limiter had something to do with it but it's something I will keep my eye on. I definitely don't want to deal with this at the track.
 

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Sounds like a little too much accelerator pump. Try a different pump cam if you can, or smaller squirter on the secondaries.
 
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