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73-87 Chevy _ GMC Trucks => Performance => Topic started by: Var on November 25, 2018, 05:52:18 PM

Title: Cam Shaft
Post by: Var on November 25, 2018, 05:52:18 PM
Peace be unto all
Iím new to the Chevy Community and need help
I have a 1985 Chevy Silverado Swb 350 engine 270 comp cam
I use to be able to hear my cam lopes very clear but every since my mechanic set the distributor back to factory, I canít hear the lopes in the cam as good.
I called him and he said to come out on the idle screw, on the carburetor so I did that and it helped some but I still donít have that classic cam sound like it sounded before he factory set the distributor. Does anyone no why this may be happening?


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Title: Re: Cam Shaft
Post by: VileZambonie on November 25, 2018, 06:13:24 PM
What's your setup? What's your idle speed? What's your timing set at?
Title: Cam Shaft
Post by: Var on November 25, 2018, 06:16:22 PM
What's your setup? What's your idle speed? What's your timing set at?



My setup supposed to to be whatever the factory setup is because he put the distributor back to GM specs
My idle speed is about 600 rpm
I have Edelbrock thunder series avs carburetor I hope in answered your questions Iím new to this so please bare with me
Title: Re: Cam Shaft
Post by: Rapid Roy on November 25, 2018, 06:36:44 PM
Welcome.
Title: Re: Cam Shaft
Post by: Var on November 25, 2018, 06:47:07 PM
Welcome.
Thank you brother


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Title: Re: Cam Shaft
Post by: 68post on February 04, 2019, 11:28:20 PM
Peace be unto all
Iím new to the Chevy Community and need help
I have a 1985 Chevy Silverado Swb 350 engine 270 comp cam
I use to be able to hear my cam lopes very clear but every since my mechanic set the distributor back to factory, I canít hear the lopes in the cam as good.
I called him and he said to come out on the idle screw, on the carburetor so I did that and it helped some but I still donít have that classic cam sound like it sounded before he factory set the distributor. Does anyone no why this may be happening?


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It was very likely running correctly before you messed with the idle mixture screws, even a stock cam can be made to "lope" if you retard the ignition timing and get the idle mixture out of whack!

My guess would be that it smoothed-out the idle because everything had been set correctly by the mechanic. Reset your idle mixture with a vacuum gauge pulling the highest vacuum (disconnect the vacuum advance and plug the leak)(keep lowering idle back to correct as you gain RPM with higher vacuum readings).

You don't really have a cam large enough to lope in a 350 if your duration is 270* seat to seat, but you have better low-end torque and throttle response than a cam that lopes does.