Author Topic: vacuum system on 305 engine  (Read 2912 times)

Offline blurred vision

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vacuum system on 305 engine
« on: December 12, 2010, 01:40:06 pm »
I'm new to the forum and just got an 86 k10.  It runs rich and hesitates when I accelerate but runs better at speed.  However when it is at speed doing fine every now and again it will almost stall out for a split second and then run fine again.  I have two questions first is what do y'all think is the problem? I have replaced the plugs and the wires and dist cap look new. So I was thinking vacuum sys. but don't know a lot about it.  I'm not sure how smart my next question is but here it goes.  How hard would it be take out the vacuum sys. and not run it?  Can it be done?

Thanks for your time,  Jason
- If you can choose what to bring to a gunfight, bring a long gun and a friend with a long gun. (unk)
- Never argue with an idiot.  They will only drag you down to there level and then beat you with experience. (unk)

Offline reallyrusty

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Re: vacuum system on 305 engine
« Reply #1 on: December 17, 2010, 07:15:41 pm »
Jason, The vacuum is not made from a system. It is created by the the pistons pulling in the air/fuel mixture.
To trouble shoot your problems, start small and go from there. Check the plugs, wires, cap, coil, filters, carb, etc.
If you have a quadrajet, check your intake manifold vacuum. The  Quadrajet will react to low vacuum by letting the metering rod
out of the jets and feeding the engine a richer mixture ( Low vacuum happens when you accelerate or you have a leak)
If you have a repair manual, use the trouble shooting section and go step by step. You might find you have several small problems that
add up to one headache. Good luck


Offline 1979C20

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Re: vacuum system on 305 engine
« Reply #2 on: December 18, 2010, 10:31:25 pm »
If you want to 'take the vacuum system out' you can minimalize vacuum lines. I need to know what you have on your system now. Picture of the engine bay would be great. Do you have vacuum canisters, what carb, smog pump? Headers or stock exhaust manifold? EGR? Stock air cleaner? Electric, manual, or hot air choke? Heater?
1979 SCLB C20 Q-jet 350 SM465 14b F.F. 4.10 G80
1989 GMC Suburban V2500 TBI350 TH400 4in lift 35's 14b SF