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Discussion Starter #1
i have a 302 30 over other than that its a stock set up, comp284 cam ( 30 30 replacement) timing is set at 18 int and 32 total. it runs fine except when i stand on it there is a slight hesitation before it winds up. this is my first 302, last summer it was suggested to me to set this timing and get rid of the vac advance. that inproved 100%. i checked for vac leaks, ok. last summer i changed the jets on the carb (new 4150) from 72 to 68. the pluggs look fine. could it be the sec spring? thanks for any input george
 

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What kind of 4150 with a sec spring? You should play with the advance a bit more IMHO. This sounds like a tuning issue to me or a skip in the accelerator pump. Something else maybe. Are you using octane booster?

-Mark.
 

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That mill was designed with vacuum advance. By removing it you bandaided the tuneup, you didn't fix it. It also came with vacuum secondaries and the spring may just be allowing them to open too soon. Also already touched on is the acellerator pump.

I would set the jets back to factory as well as make sure the entire carb (floats, throttle blades, accellerator pump ect.) is adjusted to Holley specs. You can find everything on the Holley web site.. Get creative with your timing light and make sure the vacuum advance and mechanical advance are functioning right. See how it runs set like it was new out of the box and then adjust from there. I think the Chassis Service Manual has the specs for how Chevy set them up also.

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...Dennis
"The '69, the '96 & the club"
 

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Discussion Starter #4
thanks for the help, i will readjust back to factory and see. im not using any octane boost and the sec spring is the same.
 

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Don't let the guy who suggested you remove the vacuum advance work on your car - he knows ZOT about cars


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JohnZ
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'69 Z28 Fathom Green
 

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Discussion Starter #6
john, i put everything back to stock and tuned it up. i still have a slight boog when i nail it. im going to mess with the timing a little more and check the gas. putting it back to stock took care of 90% of the problem. im going to stick with advice from people that KNOW whats going on. thanks, george
 

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The bog you mention is a common carb problem. With a Holley it can usually be fixed by either adjusting the accelerator pump, getting a different accelerator pump cam (Holley sells these and they're cheap) or stepping up to a larger power valve. Just some things to try. Also, make sure your floats are set right - open up the site plugs when the car is running and bump the car. A little fuel should slosh out. If not, then start here - could be that simple but I'm betting on the accelerator pump. It's what gives you that extra fuel when you nail it. Jon
 

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<BLOCKQUOTE>quote:</font><HR>Originally posted by JonT:
The bog you mention is a common carb problem. With a Holley it can usually be fixed by either adjusting the accelerator pump, getting a different accelerator pump cam (Holley sells these and they're cheap) or stepping up to a larger power valve. Just some things to try. Also, make sure your floats are set right - open up the site plugs when the car is running and bump the car. A little fuel should slosh out. If not, then start here - could be that simple but I'm betting on the accelerator pump. It's what gives you that extra fuel when you nail it. Jon<HR></BLOCKQUOTE>

JonT, just to satisfy my curiosity. Should a 30cc or the 50cc be used in this case?
 

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It sounds to me like you need a bigger squirter and adjust your total timing to the ballpark of 36 deg. and go from there..Hope this helps.

Jim
 
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