acceleration problem

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May 27, 2006 | 05:13 PM

lscolonel

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acceleration problem

Just did the 500 mile oil change on my 390 and everything is perfect except when I hit the gas from an idle it doesn't put you to the seat till about 2300 rpms then its like a rocket fired in the bed. Is my timing off, carb set up wrong,...I'm lost.

May 27, 2006 | 10:35 PM

Putt

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From: Colville, Washington

Need more truck and engine info, please.

May 27, 2006 | 11:56 PM

lscolonel

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Sorry... 2wd, C6 auto, edelbrock intake and 600 carb, headers, other than that pretty stock. Just let me know what else you need to know.

May 28, 2006 | 11:53 PM

Putt

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From: Colville, Washington

I would start by checking the timing to see that it advances properly(ie. smoothly and evenly). Do you have vacuum advance and if so, where is it hooked up to? If hooked up, does it work? What is your initial timing set at?

The headers can(at times) cause a carburetor to run lean and some of the Edelbrock carbs are quite lean in their factory setting, which carb model do you have? Have you checked to be sure the accelerator pump is working properly?

The RPM this is occuring at makes me think either advance is not correct(timing) or there is a problem in the enrichment or idle circuits in the carb.

May 29, 2006 | 12:23 AM

lscolonel

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how do I check the vaccum advance, it's hooked up at the carb (1406), I already fattened up the primary, it doesn't bog it's just like theres nothing there at a start.

May 29, 2006 | 04:47 PM

Putt

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From: Colville, Washington

If you do not have a vacuum pump, the easy way is to find a manifold vacuum source(sucks at idle) and connect the vacuum advance can to that while the truck is idleing. If the advance is working, the idle speed will increase and then slow back down when you pull the hose off. You can see the change in timing if you have a timing light connected and watch the marks. BTW, don't leave the port open when you unhook the vacuum adv can, that will change the idle due to the vacuum leak.

Do you have any cam info or other pertinent specs on the motor??

May 30, 2006 | 12:41 AM

lscolonel

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cam specs are 214 dur @.050, .466 valve lift, heads are stock cast and I honsetly don't know how far it was bored, it's a crate motor and I didn't want to pull the heads just to put them back on. Thanks for all the help I am going to check the vaccum advance and check to make sure my timing is where I want it hopefully tomorrow after work. My friend said he has a vaccum guage how much is normal for the motor?