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Re: Still can't get out of the 13's,. Critique please
[Re: BSB67]
#1005561
06/04/11 04:15 AM
06/04/11 04:15 AM
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Joined: May 2008
Posts: 5,399
Aurora, Colorado
451Mopar
master
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master
Joined: May 2008
Posts: 5,399
Aurora, Colorado
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Quote:
The hesitation is from a lean condition, and it happens 20 to 25 ft out. So, it could be the squirter duration may needs to be lengthened. Or it could be that the vacuum secondaries are starting in a bit too early. If tuning the squirter does not help, try a slightly stiffer secondary vacuum spring. These are all simple things that you should do at the track to get it right.
Try a green accelerator pump cam, it has a good long pump shot. Try position #1 first, if it's still lean, use position #2 on the accelerator pump cam.
On my carb, I blocked the rear power valve, added the rear screw-in jet extentions, and a notched float to clear the extentions. I also got the quick-change fuel bowls. They make jet changes pretty simple.
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Re: Still can't get out of the 13's,. Critique please
[Re: 451Mopar]
#1005562
06/04/11 08:25 AM
06/04/11 08:25 AM
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Joined: Jul 2004
Posts: 4,732
Watertown, WI
MikeyT
OP
master
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OP
master
Joined: Jul 2004
Posts: 4,732
Watertown, WI
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Ok to answer questions. The only change from last fall was change in torque converter and gears. It now has a 4500 stall converter built special by PTC. I also geared the car up to 3:91's. I changed shift points from 5600 to 5800. So, as you can see lots of variables. Now I was thinking about this, and put this into perspective. The best time I've ever run with this car at GLD was last fall was 13.4 @ 104 mph. So technically it was a success because I was able to pick up 4 tenths. Weather wise, honestly was pretty close between the 2 times, weather was mid 70's normal humidity, of course this is subjective. I think my plan is to go with the suggestions for the carb, and then rexamine driving technique. I might return to shifting the car at 5600, and work on launch! Wayne (Big Squeeze) gave me some good suggestions at getting out of the hole better. Oh Rob I heard you about the DP buddy  Again, you all are really awesome! Thank you for the idea's to try. I'll make some minor adjustments and hopefully give this another shot next weekend Mike
1969 Dodge Dart Swinger
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Re: Still can't get out of the 13's,. Critique please
[Re: MikeyT]
#1005563
06/04/11 10:24 AM
06/04/11 10:24 AM
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Joined: Feb 2005
Posts: 4,314
Prospect, PA
BSB67
master
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master
Joined: Feb 2005
Posts: 4,314
Prospect, PA
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Quote:
Ok to answer questions. The only change from last fall was change in torque converter and gears. It now has a 4500 stall converter built special by PTC. I also geared the car up to 3:91's. I changed shift points from 5600 to 5800.
So, as you can see lots of variables. Now I was thinking about this, and put this into perspective. The best time I've ever run with this car at GLD was last fall was 13.4 @ 104 mph. So technically it was a success because I was able to pick up 4 tenths. Weather wise, honestly was pretty close between the 2 times, weather was mid 70's normal humidity, of course this is subjective.
I think my plan is to go with the suggestions for the carb, and then rexamine driving technique. I might return to shifting the car at 5600, and work on launch! Wayne (Big Squeeze) gave me some good suggestions at getting out of the hole better.
Oh Rob I heard you about the DP buddy
Again, you all are really awesome! Thank you for the idea's to try. I'll make some minor adjustments and hopefully give this another shot next weekend
Mike
I bet the converter and gear change is making the secondaries come in too quick now. The secondaries are probably slamming open at the 20 ft point. I would put a stiffer secondary spring in.
You can go on line to Dragtimes and check the DA for all of your past runs, and make a pretty good assesment of the performance changes for all of your track runs.
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Re: Still can't get out of the 13's,. Critique please
[Re: BSB67]
#1005564
06/04/11 10:56 AM
06/04/11 10:56 AM
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Joined: Oct 2008
Posts: 1,015
Down South
DaKuda
super stock
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super stock
Joined: Oct 2008
Posts: 1,015
Down South
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Re: Still can't get out of the 13's,. Critique please
[Re: DaKuda]
#1005565
06/04/11 11:43 AM
06/04/11 11:43 AM
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Joined: Jan 2003
Posts: 9,875
Weddington, N.C.
Streetwize
master
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master
Joined: Jan 2003
Posts: 9,875
Weddington, N.C.
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 You gotta be careful with pump cams, what helps at the end of the shot could hurt somewhere else earlier on. The default pump cam I used in a heavy B body was the Pink cam in the #2 position with a 31 shooter. The # 2 position comes in late so you might try that first, it normally works the best in vacuum secondary carbs. The bog (looked more like just a 'lay down' lag to me) may also (most likely IMO) be the vacuum spring is just not opening soon enough, get a quick change kit and experiment, try the Purple spring first and go up or down from there. Concentrate on your 60's, I have a feeling if you fix that the rest will take care of itself. I agree 200 is way too hot, use a robertshaw 160 and I drill a couple 1/8" holes in it around the perimeter edge just to prevent hot air pockets from being trapped in the system.
Last edited by Streetwize; 06/04/11 11:45 AM.
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Re: Still can't get out of the 13's,. Critique please
[Re: dustergirl340]
#1005568
06/04/11 05:02 PM
06/04/11 05:02 PM
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Joined: Feb 2005
Posts: 5,221
Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Sounds like a secondary problem too me, A pump shot issue will be an "abrupt" stumble then clear fast if the rest of the metering is on track, You need to play with the springs in the secondary pod, It sounds like its coming in too quick, so its a lean bogg, I also agree with street, you really shouldn't need alot of pump shot. The temp is also too high at 200*, at least try & have it at 170* in the box, I normally leave at no more then 180*, but i try & keep the carb as cool as possible, another thing, When it starts heating up outside & your engine is on the warm side, It will run richer then in cool air, so IMO, increasing the pump shot may worsen the 60ft. But i think its in the scondaries. 
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