rev problem on sbc 350 - Team Camaro Tech
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post #1 of 5 (permalink) Old Oct 31st, 11, 01:35 PM Thread Starter
Michael
 
Join Date: Oct 2011
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rev problem on sbc 350

Hello all, I'm new here and i need some help with this problem.
I have a sbc 350 that i built a year ago and whenever i rev the motor up (in park)to around 3000 rpm's or higher and try to keep it there, it will run smoothly for about 2 seconds and slowly descend to lower rpm's and sound very rough during the descend. I think it could be a carburetor problem or ignition problem. but could it be something internally like the valvetrane?
I had the rotating assembly balanced, running a large cam and mechanical fuel pump.
any help is appreciated!
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post #2 of 5 (permalink) Old Oct 31st, 11, 02:17 PM
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Steve
 
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Re: rev problem on sbc 350

Sounds like it's running out of fuel.

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post #3 of 5 (permalink) Old Oct 31st, 11, 02:46 PM Thread Starter
Michael
 
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Re: rev problem on sbc 350

I adjusted the carb to run a little more rich and played with the timing a bit but that didn't help.
also,it doesn't die it just descends to idle
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post #4 of 5 (permalink) Old Oct 31st, 11, 04:39 PM
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Re: rev problem on sbc 350

If it idles, could be the main circuit needing a good cleaning, ie, remove carb, tear apart and spray the bejesus out of it with carb aerosol cleaner and reassemble and adjust.

Could be float level is too low.

A good troubleshooting tip, while carb is open on the engine, spray some WD40 into the throat/air horn to see if engine rpm picks up. If it does, fuel delivery problem in carb.

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post #5 of 5 (permalink) Old Nov 3rd, 11, 09:12 AM Thread Starter
Michael
 
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Re: rev problem on sbc 350

I just rebuilt the carb and i remember accidentally bending the floats, they may just need some proper adjusting.Thanks for mentioning the float level!
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