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08-08-2013, 12:24 AM
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#1 |
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Registered User
Join Date: Aug 2012
Location: Newington ct
Posts: 177
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Timing ?
I have a new crt performace hei. Also a edelbrock 1404 on a 78 inline 250. The issue is its deiseling for like 20 seconds after shut off and then one loud backfire like a cannon. Not sure how to handle this is it timing or the idle mixture on carb?
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08-08-2013, 12:29 AM
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#2 |
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Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Timing ?
Idle mixture can do this. Hot engine can do this. Timing can do this. Not enough octane can do this. I can be a hard thing to diagnose. So if you make changes do one at a time.
What's your initial timing set at First off? Posted via Mobile Device
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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08-08-2013, 02:21 AM
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#3 |
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Registered User
Join Date: Jun 2013
Location: Oregon
Posts: 89
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Re: Timing ?
i have a 292, and my engine did this for the first couple of months i had it. i was new to carbs and older trucks. talked a guy at work and tryed all his suggestions. got a new carb, kept doing it. it came down to my idle being too high. also i was leaking gas with the first carb, that caused it to diesel too.. it took a day or two of turning the truck off even when my idle was correct to stop dieseling. just my two cents. id listen to the guy above. hes helped me already a couple times since ive been on this site.
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79' c20 std cab 292 3speed granny - daily driver. 77' c30 std cab 454 th400 4.10 - fathers truck then mine. 95' ford bronco 302 4speed overdrive. 2002 mustang auto v6 - girlfriends daily driver. Debt just means that you had more fun than you're suppose to have |
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08-08-2013, 01:34 PM
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#4 |
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Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Timing ?
My engine did it a lot and it was the idle being to high. The throttle was to far open. I lowered it and it helped then I re adjusted mixture, since my engine is a v8 single plane the mixture distribution was off and a re adjustment fixed it more.
In the mean time you can keep it in gear and shut it off and see if that helps Posted via Mobile Device
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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08-08-2013, 02:52 PM
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#5 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,733
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Re: Timing ?
If you can't reduce the idle then hook the vac advance to a manifold vac port. Increased timing will speed up the motor then you can turn the idle down on the carb.
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08-08-2013, 03:13 PM
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#6 |
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Registered User
Join Date: Aug 2012
Location: Newington ct
Posts: 177
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Re: Timing ?
And another thing that's strange is that I also have the idle screw all the way out and still idles about 900rpm
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08-08-2013, 03:33 PM
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#7 |
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Registered User
Join Date: Aug 2009
Location: Bowser
Posts: 13,733
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Re: Timing ?
Manual choke i presume. How about the high idle screw on the choke. Is it backed off all the way?
Possibly the secondary throttle plate is hung open or you have a vacuum leak. What intake you using? |
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08-08-2013, 05:27 PM
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#8 |
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Registered User
Join Date: Aug 2012
Location: Newington ct
Posts: 177
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Re: Timing ?
No it's electric. I haven't messed with that screw so like half out. Offenhauser intake
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08-08-2013, 05:30 PM
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#9 |
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Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Timing ?
Could possibly have an intake leak if the idle screw is backed all the way out
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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08-08-2013, 05:47 PM
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#10 | |
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Join Date: Aug 2009
Location: Bowser
Posts: 13,733
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Re: Timing ?
Quote:
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08-08-2013, 07:17 PM
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#11 |
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Registered User
Join Date: Aug 2012
Location: Newington ct
Posts: 177
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Re: Timing ?
Do you guys thing the idle being a little high because I mean little by like 150 rpm is because the hei is to far advanced ?
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08-08-2013, 07:31 PM
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#12 |
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Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Timing ?
What's the timing set at on the initial. Shouldn't be more than 12*
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377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511 |
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08-08-2013, 08:25 PM
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#13 |
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Registered User
Join Date: Aug 2012
Location: Newington ct
Posts: 177
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Re: Timing ?
I don't know just slid the old dist out and put the new hei the same way. I'm an idiot
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