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  #46 (permalink)  
Old 02-08-2008, 02:16 PM
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Tell us about your sent up again (it has been awhile, so I forgot). gear, stall, cam, exhaust, transmission, ect.

I know you have a 307 in a 77 nova right?

did you sent the 16 degrees without the vacuum advance connected? Need to sent the time without the vacuum advance connected.

Try more timing? sure. try 20.

yes, you can also try a bigger squirter. what size are you using now?

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  #47 (permalink)  
Old 02-08-2008, 02:17 PM
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Run it over 3000 rpm and set it with vacuum and centrifical hooked up and at maximum total advance to 38 degrees. This is a good starting point for checking for power. You might even try it at 42 total degrees.
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Old 02-08-2008, 03:02 PM
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no, with vacuum advance connected it should be over 50 degrees when revving the engine in park at 3000 rpm.

yes, 38 degrees total of just mechanical advance (not including vacuum advance)

Best mpg for an old school sbc is 50 to 53 degrees while driving down the highway with no load (high vacuum). The extra timing from the vacuum advance drops out quickly when the throttle is opened for passing activities.
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  #49 (permalink)  
Old 02-08-2008, 03:29 PM
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check out this ignition timing write up.

http://www.vetteclub.org/technicalti...101Article.pdf

he is saying 10 initial, 30-35 with mechanical added in, and 45-50 total with the vacuum advance. Of course this is most likely with a stock cam. I had better mpg with a little over 50 degrees and have read a few other timing papers stating the same thing. A bigger cam than stock, needs more timing to run right so that may be the reason why I found the need for a little more timing.
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  #50 (permalink)  
Old 02-08-2008, 09:20 PM
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Quote:
Originally Posted by duntovman
oooh yes i did when and engine is 180 only means that number one and number 6 are crosswired by the dist. or mabye your not wise enough to know that .they will still fire and run if the timing is advanced far enough .
Oh I get it, so you fire the plug while the exhaust valve is open. How exactly does the uncompressed charge burn and force the piston down.
As I said before it is impossible.
Please dont give out bad information as many people rely on this to get there vehicles fixed.
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Old 02-13-2008, 03:38 PM
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set it at 20 btdc an a little twirp in the tire.power braked it and SCRRRRRRR.smoke everywhere and bits of tire flyin!maybe my gearing is just real high.anyways thank YOU ALL BIG KISSES MUAHH!
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Old 05-23-2011, 02:17 PM
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back fireing through the carb

hi, been reading comments about backfireing through carb, i still have the trouble, checked the plugs ,wires, vac, valves, distributor,timming when i put timming a 12d it worked better, but still back fired . the carb was a 780 went to a 750 worked better but still.the dis is good got to be some body who has a solution to the problem, 69 302 z28, oh no vac leeks checked intake also
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Old 05-23-2011, 02:56 PM
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also look for a blowed out power valve
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  #54 (permalink)  
Old 05-23-2011, 04:14 PM
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run more timing. try 20 initial.
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Old 05-23-2011, 04:25 PM
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z28

so on my balancer that would be 14d my timing light is just a light with the degrees on it and i just put it on o and look @ my balancer and put it to my marks
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  #56 (permalink)  
Old 05-23-2011, 04:35 PM
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put the light on 20 then set the timing marks at 0.
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Old 05-23-2011, 04:36 PM
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Quote:
Originally Posted by 67-4-fun
also look for a blowed out power valve
hi ,yea ithought of that so changed itto 6.5 ,how many times can you back fire a valve before you have to change it .Ichecked the valve i guess suck on the valveony and lisen for air to pass is this right
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  #58 (permalink)  
Old 05-24-2011, 06:25 AM
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Quote:
Originally Posted by 222222
hi ,yea ithought of that so changed itto 6.5 ,how many times can you back fire a valve before you have to change it .Ichecked the valve i guess suck on the valveony and lisen for air to pass is this right
When exactly does it backfire, when accelerating, at idle at cruise.
A blown power valve will not make it backfire, it can however be damaged by a backfire. Usually backfire through the carburetor is caused by a lean condition, firing order or timing issue. There are other potential causes like a sticky valves or electronic ignition issues but they are not as common.
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Old 05-24-2011, 07:53 AM
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back fire

hi, it backfires a idle when you check for throttle response ,which is the ****s. as for ignition i put a hevy duty petronicks coil in , im thicking of removing the points , and putting level 2 petronics in and i know the dis not 180 all though it would still run as long as you put number1 on the back side have done that before .
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  #60 (permalink)  
Old 05-24-2011, 09:32 AM
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You are still running points? Get rid of it. The bearing in the distributor may be worn. To have sooty plugs and backfire I think you may have a very weak ignition system.
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