Popping

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Speedster
Posts: 183
Joined: Mon Feb 08, 2010 2:35 pm
Location: Aloha, Oregon

Popping

#1 Post by Speedster » Sun May 09, 2010 12:14 pm

went to the track saturday and we started popping badly. I have video of it where you can hear the popping.
from the video what do you think is causing this? if you read the discription it has all the info.
http://www.youtube.com/watch?v=dvssnCPNwUQ

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CDR Performance
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Re: Popping

#2 Post by CDR Performance » Sun May 09, 2010 1:17 pm

Do you have wideband?

OK that out of the way... lol

Motor and carb?
Carb set-up? jets? float?
Front and rear throttle position?
Acc Pump?
Squirter?
Tell us what you did?
Stage rpm?
Two-three step?
Transbrake? or not?
Throttle position staged?
Was the car dead hooking?
CDR PERFORMANCE
The Custom Engine Shop

Dart - Callies - BRC - Oliver - BME - Custom Cams - T&D - Trend - JGS - BorgWarner - SuperNatural - EV - CSU - C&S - BS3

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Speedster
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Location: Aloha, Oregon

Re: Popping

#3 Post by Speedster » Sun May 09, 2010 4:38 pm

CDR Performance wrote:Do you have wideband?

OK that out of the way... lol NO. LOL

Motor and carb? 355 SBC HOLLEY 600 VAC SEC.
Carb set-up? jets? float? 66FRONT 68REAR LEVEL SET JUST BELOW WINDOW
Front and rear throttle position? NO IDEA
Acc Pump? 30CC PROBLY BAD?
Squirter? NOT SURE
Tell us what you did? CHANGED HEADS AND INTAKE PUT OLD CARB ON. GOT BETTER TURNING IDLE MIX INTO 1/2 TURN
Stage rpm? FLOORED
Two-three step? NO
Transbrake? or not? TRANS BRAKE 4000 STALL
Throttle position staged? DONT KNOW
Was the car dead hooking? YES CAR HOOKED NICE

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CDR Performance
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Location: Indianapolis, Indiana

Re: Popping

#4 Post by CDR Performance » Sun May 09, 2010 8:12 pm

So it was floored on the t-brake @ 4000.

And then it was popping before you released the brake or after.
CDR PERFORMANCE
The Custom Engine Shop

Dart - Callies - BRC - Oliver - BME - Custom Cams - T&D - Trend - JGS - BorgWarner - SuperNatural - EV - CSU - C&S - BS3

http://www.cdrperformance.biz

want-a-be
Posts: 189
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Location: Southern Illinois

Re: Popping

#5 Post by want-a-be » Sun May 09, 2010 9:28 pm

What heads did you have on it before and what did you put on it?
Cam:
compression:
intake:
timing:

Don

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Speedster
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Re: Popping

#6 Post by Speedster » Sun May 09, 2010 10:27 pm

It's not popping once your on the trans brake or going down the track at wot.
only when you are at idle and touch the pedal it pops. In the video he rolled back out of the lights so he was auto red and he sit there and the starter told him to go so left from idle and you can hear it pop loud. I turned the idle mixture screws in and took care of most of the popping but that was our last pass so i could not try it again.

Don it had 194 cast heads and i put on a set of 195cc runner aluminum heads with 2.02 valves both were 64cc chamber.
Compression is the same. 10.3to 1 pistons. timing is at 36deg total at 4000 rpm all in msd ignition 6al box 6300 chip.
intake is the hurricane the vic jr knock off.

i think it blew the power valve? but i have not tore into that carb. the carb i wanted to use is being rebuilt.

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CDR Performance
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Re: Popping

#7 Post by CDR Performance » Mon May 10, 2010 7:39 am

What pump cam in on the arm? (color)
CDR PERFORMANCE
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Dart - Callies - BRC - Oliver - BME - Custom Cams - T&D - Trend - JGS - BorgWarner - SuperNatural - EV - CSU - C&S - BS3

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Speedster
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Re: Popping

#8 Post by Speedster » Mon May 10, 2010 10:12 am

Brown.
I'm going to re run the valves this week and hopefully have my good carb back on the car.
I noticed last night that the header gasket blew out between cylinder 3-5 and i wonder if that might have played a role?

sc racing
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Re: Popping

#9 Post by sc racing » Mon May 10, 2010 10:21 am

Sounds like a lean condition, most off idle pops/stumbles can be fixed by going to a larger discharge nozzle. im not saying this is definitly your problem but thats what it sounded like in the video.When you said you turned in the idle mix screws how do you know they are correct? Turning them in leans out the mixture,put a vacuum gauge on the vac source and adjust screws to get the highest vacuum reading. Ill bet you have a .028 nozzle if you have pin drills you can drill it to an .031 or bigger if needed. I would also try to launch off the footbrake around 1500-1800 rpm so you still have some pump shot.If you blew a power valve you will be running extremely rich as fuel will be dumping in,most carbs now have blowout protection so it might be ok.

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Speedster
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Re: Popping

#10 Post by Speedster » Mon May 10, 2010 1:03 pm

It's a old street carb 600 vac sec that is a pos. :lol:
i was thinking the same thing on the squirters either to small or a bad diaphram gasket?
but what threw me was i turned in the mixture screws and it got better? 70 deg day running sunoco 110 fuel sea level should have been good? this carb has never had race fuel in it before?

sc racing
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Re: Popping

#11 Post by sc racing » Wed May 12, 2010 8:03 am

After reading that your putting your other carb on the car I wouldnt even try to fix this one.

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Speedster
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Re: Popping

#12 Post by Speedster » Tue May 18, 2010 10:47 pm

Well i started to rebuild the POS even though im putting my 750hp on the race car.
When i tore into the 600vac sec carb i found a very crusty burnt power valve and i mean burnt like caught on fire?

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Speedster
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Re: Popping

#13 Post by Speedster » Sun Jun 06, 2010 5:19 pm

Update: incase anyone else has this problem i fiqured i would fill in the solve for my popping.
After changing carbs to my good holley that i rebuilt it was still popping when i tryed to start it cold or when i tryed to give it gas.
so two carb doing the same thing i was pretty sure it was something in the engine(valve or spring) that was broke bent or burnt?
I talked with my engine builder again and he said that i was just super lean with the change of a hi rise intake and new aluminum heads with bigger valves and he had told me weeks earlier that i was lean but i would'nt listen because the carb was working on the old set up just fine and i was just sure it was something else? :oops: Well after spending quite a bit of money on all the stuff i was thinking it was and compression testers and vacuum gauges and re-adjusting my valves 3 times i decided to start going up on my jets and see what happened? well after going up 10 sizes on the jets and from .28 squirters to .35 squirters and changing the cam on the accelorator pump arm from the clear colored cam to the orange colored cam im happy to say the car is running great and im very happy with the response i get from the new combination and i have now ran the quickest ET yet. when i started this project we had a best run of 12.84 108mph. after the new aluminum heads and hi rise intake we have now ran 12.21 ET and our best mph is now 112.43. so just over a half second gain and 4 mph and no more popping! :thumb:
I would like to thank all of the people on this site for helping me and there were a couple of guys who hit it right on the head but i was'nt listening? :nutkick:

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