running rich
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Joined: May 2006
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From: seattle wa
running rich
ok afew weeks back iinstalled a thumper cam with my new edelbrock carb i changed needles to 4% leaner and still running rich timing set at 10 deg seems to run good but rich and when driving in town after awhile wants to stall and when i shut off and restart if igive any gas then its hard to keep running until iget on it and then runs fine is my car running rich becouse of the over lap with cam 107 separation help please
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ok afew weeks back iinstalled a thumper cam with my new edelbrock carb i changed needles to 4% leaner and still running rich timing set at 10 deg seems to run good but rich and when driving in town after awhile wants to stall and when i shut off and restart if igive any gas then its hard to keep running until iget on it and then runs fine is my car running rich becouse of the over lap with cam 107 separation help please
These cams, especially the larger ones, want a ton of initial timinig.. Your 10 degress of initial is WAY to low, you should be up around 18 (or even more) but make sure your total isnt to high when doing so, which may require different springs in your distributor.. When it comes to big loping cams, you have to drive them. If you do a handful of cold starts without driving it, you will foul plugs.. With a fresh set of plugs, I cant do more than 3 or 4 cold starts without fouling plugs unless I drive it.. Once you drive and warm it up, you can do alot more idling around. Cold starts are the worse when it comes to fouling plugs with big cams..
I run my timing locked out at 38 degrees but that does require an ignition cutoff switch when trying to start it when its warm. From a dead idle my car will launch hard which is pretty good since my cam dur is 250 @ .050.. Your timing should be all in by 3000rpm
Does it hesitate any off idle? IF so, you will need to open your secondary butterflies slightly..
Last edited by Fishndude; Aug 29, 2010 at 08:04 AM.
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The package should tell you which springs.. Try the ones that wil give you 20 degress and be all in by 3000rpm and start out at 16 initial and then check to see if you have 36 by 3000.. If you dont have an spark knock, you could try bumping it up another 2 degrees and see if it runs even better... The 279 isnt that stout so it should run good with that kind of timing (16-36).. Set the timing first and then dial in the carb if it needs it.. Throttle response should be better with more initial timing and your idle should feel a little smoother too but still lope.. You should be able to idle at 800rpm..
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Joined: May 2006
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From: seattle wa
well it turns out the float bowls on the edelbrock we off so now its set at 16*deg with total of 36 @ 2800 rpms idles at around 900 rpms and when in gear about 600 so everything seems to be good now I'm thinking of puting in a different stall any suggestions also if i put in a 2500 stall will i have to have a trans cooler thanks
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Joined: Mar 2009
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well it turns out the float bowls on the edelbrock we off so now its set at 16*deg with total of 36 @ 2800 rpms idles at around 900 rpms and when in gear about 600 so everything seems to be good now I'm thinking of puting in a different stall any suggestions also if i put in a 2500 stall will i have to have a trans cooler thanks
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Joined: Jul 2010
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From: Boynton Beach Florida
I have the 279 Thumpr in my 76 350ci. I tried an Edelbrock carb but it just didn't do what I wanted. I finally put a Holley 770 Street Avenger with bigger squirters and increased the primary jet size. What Fishndude said about timing is the KEY to getting the Thumpr cams to work. My base timing is 26 degrees with an MSD ProBillet Distributor. I changed the springs to the light blue ones. I run 93 octane with the 9.6 to 1 compression I get from my Edelbrock aluminum heads on stock pistons and this thing runs great. I idle in park at 1000-1100 and 700 in gear. No hesitation, no nothing.
It took awhile to figure out what the cam wanted but the first thing I determined after talking to Fishndude via youtube many months ago was to listen to the engine not what you we have all been taught to do with an engine. Normal setups won't cut it with the Thumpr cams. Feel free to check out some of my videos and you'll hear what mine sounds like and the idle speed I'm running at for a reference to yours. I still have the stock convertor though I have thought about going with a 2600-2800 but the more I tuned the car the more I found the stock converter works just fine for street driving, however racing would be a different story.
http://www.youtube.com/watch?v=Ytin0F0PJzI
http://www.youtube.com/watch?v=BdoSr...eature=related
It took awhile to figure out what the cam wanted but the first thing I determined after talking to Fishndude via youtube many months ago was to listen to the engine not what you we have all been taught to do with an engine. Normal setups won't cut it with the Thumpr cams. Feel free to check out some of my videos and you'll hear what mine sounds like and the idle speed I'm running at for a reference to yours. I still have the stock convertor though I have thought about going with a 2600-2800 but the more I tuned the car the more I found the stock converter works just fine for street driving, however racing would be a different story.
http://www.youtube.com/watch?v=Ytin0F0PJzI
http://www.youtube.com/watch?v=BdoSr...eature=related
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Thread Starter
Instructor
Joined: May 2006
Posts: 131
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From: seattle wa
so took car out for a drive seems to run good but i still have a issues with car after i shut it off when i go to start it if i give itgas it doesn't want to stay running very temperament it will run if i don't give gas but it takes s bit to start
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Eric's car sounds SWEEET!!!
Edit: Like Eric (palmbeachvette76), I favor Holleys and dont know much about Edelbrock carbs but it does still sound like a carb tuning issue.. Since you and Eric are running the exact same cam, I would follow his lead.. Even he is running alot of intial timing (26 degrees) and a good size carb (I run a BG 750DP) that has been modified and adjusted based on what the engine wants..
Edit: Like Eric (palmbeachvette76), I favor Holleys and dont know much about Edelbrock carbs but it does still sound like a carb tuning issue.. Since you and Eric are running the exact same cam, I would follow his lead.. Even he is running alot of intial timing (26 degrees) and a good size carb (I run a BG 750DP) that has been modified and adjusted based on what the engine wants..
Last edited by Fishndude; Sep 5, 2010 at 07:27 AM.
