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 Post subject: ANOTHER CARB QUESTION
 Post Posted: Sat Oct 01, 2011 9:36 am 
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JMARKAUDIO & others who have gave me ideas,
we have been talking about a 1050 i put on my 406 monte carlo,right out of the box it didnt want to run so i took out the power valves and left the 88's in.1st pass 10.26 @129mph,pulled plugs porcilin was white after idleing back to trailer. put in 91 square, my friend adjust the 4 corner idle car went 10.17 @129. i shited 1-2 before the shift light came on, i shift @ 7200rpm.next pass i waited for the shift light(1-2) and it hesitated a little before it came on,2-3 it does not hesitate when i wait for shift light.any ideas what is going on?

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 Post Posted: Sat Oct 01, 2011 10:23 am 
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88's with no PV is going to be lean, 92 is probably closer. Jet up 1 at a time to see if you gain any MPH, if it slows right away try 91 then 90 if it picks up. You are looking for best MPH, jetting for best MPH shows most engine power.

Picking up time from shifting first gear early with a 3 speed isn't uncommon.

As far as hesitation, what is hesitating, engine or the shift?


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 Post Posted: Sat Oct 01, 2011 12:56 pm 
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I'm with jmark on the jet thingie except I would jet up 2 steps at a time until it gets phat and slows down and again as Mark says, tune by MPH not ET and I'll add this, make all your tuning runs at the same track in the same lane and if you can, try to do all that in one day so conditions won't be that much different start to finish!!

And use the same method to set the timing too, ie, bump down 2* and read MPH. If it likes that, then do it again! If it didn't, then go the other way but I'd play with the jet first so as not to run it too lean with too much timing.

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 Post Posted: Sat Oct 01, 2011 1:40 pm 
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I agree with everything said but also make sure you shift it at the same rpm EVERY time when your tuning with the jets..

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 Post Posted: Sun Oct 02, 2011 8:31 am 
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jmarkaudio wrote:
88's with no PV is going to be lean, 92 is probably closer. Jet up 1 at a time to see if you gain any MPH, if it slows right away try 91 then 90 if it picks up. You are looking for best MPH, jetting for best MPH shows most engine power.

Picking up time from shifting first gear early with a 3 speed isn't uncommon.

As far as hesitation, what is hesitating, engine or the shift?

Right before the shift light comes on it sputters(1-2 shift).

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JEFF WINTERS
1986 SS MONTE CARLO
406 SBC
BEST TIME TO DATE 9.99 1/4 MILE @132MPH.


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 Post Posted: Sun Oct 02, 2011 9:59 am 
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JEFF69Z28 wrote:
Right before the shift light comes on it sputters(1-2 shift).


So how far is your high RPM rev limit from your 1-2 shift point? :-k

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 Post Posted: Mon Oct 03, 2011 5:00 am 
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Ken0069 wrote:
JEFF69Z28 wrote:
Right before the shift light comes on it sputters(1-2 shift).


So how far is your high RPM rev limit from your 1-2 shift point? :-k

REV LIMTER SET AT 7800 RPM

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JEFF WINTERS
1986 SS MONTE CARLO
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BEST TIME TO DATE 9.99 1/4 MILE @132MPH.


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 Post Posted: Mon Oct 03, 2011 9:11 am 
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Fuel pressure at the sputter? :-k

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 Post Posted: Mon Oct 03, 2011 9:17 am 
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Valve springs/Ign???

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 Post Posted: Mon Oct 03, 2011 10:11 am 
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Never thought to look at fuel psi,valve springs were checked last year before i stopped racing.I dont think its the ignition because it only does it before i shift into second gear,its fine going into 3rd and at 7300 when i cross the line.

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1986 SS MONTE CARLO
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BEST TIME TO DATE 9.99 1/4 MILE @132MPH.


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 Post Posted: Mon Oct 03, 2011 1:10 pm 
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I may be wrong here but I'd venture to guess that the highest volume of fuel consumption over time is from the hit through first gear, ie, fuel used over xx amount of time. That and "G" forces at the launch may be slowing fuel delivery down enough in low gear to where it might create problems. You really need to check this next time out. Of course if you had an O2 sensor recording AFRs on that thing you could see it in the graph.

So what stuff is in the fuel system cell to carb and is this a trunk mounted fuel cell? :-k

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 Post Posted: Tue Oct 04, 2011 4:48 am 
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Ken0069 wrote:
I may be wrong here but I'd venture to guess that the highest volume of fuel consumption over time is from the hit through first gear, ie, fuel used over xx amount of time. That and "G" forces at the launch may be slowing fuel delivery down enough in low gear to where it might create problems. You really need to check this next time out. Of course if you had an O2 sensor recording AFRs on that thing you could see it in the graph.

So what stuff is in the fuel system cell to carb and is this a trunk mounted fuel cell? :-k

Tank in trunk #8 to filter to holley blue pump then to aeromotive fuel reg. then to carb.

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JEFF WINTERS
1986 SS MONTE CARLO
406 SBC
BEST TIME TO DATE 9.99 1/4 MILE @132MPH.


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 Post Posted: Tue Oct 04, 2011 7:21 am 
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You need a bigger pump. Even if you think thats not the problem the car will go faster with a bigger pump. You will be able to tune the carb better.


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 Post Posted: Tue Oct 04, 2011 7:44 am 
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shrinker wrote:
You need a bigger pump. Even if you think thats not the problem the car will go faster with a bigger pump. You will be able to tune the carb better.

how much bigger and what do you suggest,anyone else like to comment on this,this has entered my mind every once in a while.

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JEFF WINTERS
1986 SS MONTE CARLO
406 SBC
BEST TIME TO DATE 9.99 1/4 MILE @132MPH.


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 Post Posted: Tue Oct 04, 2011 9:50 am 
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I would agree. I haven't used a Holley pump in years and I thought the blue pump was a street pump and not really adequate for more serious race application. Holley's website specs it at 110 GPH and I wouldn't think that would be enough for a low 10 second car.

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