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#1 |
Registered User
Join Date: Feb 2013
Location: Sudbury Ontario
Posts: 1
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Setting timing?
I have a 1984 GMC High Sierra with a 305. I was wondering if anyone on here knows what the timing should be set at, I have looked around and I keep getting different answers. I found one answer that said between 8 and 10 degrees btdc is good enough but then i found another answer that said 6 degrees btdc is where it should be. Does anyone here know for sure?
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#2 |
Registered User
Join Date: Aug 2009
Location: S.C.
Posts: 1,593
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Re: Setting timing?
If you want "official" timing, I'd have to look it up.
10-12 btdc will run better, of course your results may differ. (if it pings, back it off) I haven't had any problems running 12 in my smallblocks. If you really want to dive in, SBC Ignition Timing. Welcome, I'll see if my Haynes manual has anything.
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'86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold ![]() I'm kinda like duct tape- no real purpose, but handy to have around. |
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#3 |
Registered User
Join Date: Jul 2009
Location: washington
Posts: 4,178
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Re: Setting timing?
My emmissions sticker on my truck says 4* initial.
That's good for emmissions but its still garbage Start a 10* and then try 12 but ten should be fine. I don't go higher unless I fix the distributor to keep full advance under or at 40. Then I limit how much advance the vacuum gets. All that won't do **** for a 305. I set mine at ten and put one med spring in the advance mechanism and that woke it up 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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#4 |
Registered User
Join Date: Aug 2009
Location: S.C.
Posts: 1,593
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Re: Setting timing?
Haynes manual lists 4 (fed) or 6 (Calif) btdc. Like INSIDIOUS '86 said, these were for emissions.
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'86 C-30 dually, 454/tbh400 '73 K-20 350/350/205 (sold ![]() I'm kinda like duct tape- no real purpose, but handy to have around. |
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#5 | |
78K & 79C Jimmys
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
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Re: Setting timing?
Quote:
my 79-2B-305 is about 10-12 advanced
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John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350 |
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#6 |
Registered User
Join Date: Mar 2012
Location: edgartown mass
Posts: 852
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Re: Setting timing?
the way i was always told and have done is start at 10 if you are at sea level and see what you get. if you are good keep turning it little by little till you get ping under wide open or kick back on the starter and then go back 3*. it will be less in the higher alt.
most of mine are at the 12-15* mark and run great with good response and milage too
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1986 c20 "the hillbilly" 350 sm465 3.42gears 21mpg at 70mph 1985 k30 "the ice cream truck from hell" no rust az truck 197-8??? c30 "ramp truck" 454 1978 monte carlo 350 350th with 2.73 gears. no rust. sc car |
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#7 |
Parts and more parts
Join Date: Nov 2003
Location: Lebo, Kansas (middle of nowhere
Posts: 6,821
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Re: Setting timing?
Just keep in mind the more retarded the timing is set, the more heat is created in the engine. The information above with the timing at 4 degrees (federal) and 6 degrees (california) is what the manual says. I always ran my engine at 12 degrees and did not get detonation. I now have my timing set on my 383 stroker with an advance timing light and I set the timing at Total advance at around 35 degrees. I have had no issue with that setup. I live in Kansa and we are quite a ways above sea level. I agree, start at 10 degrees and play with it.
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Frank |
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#8 |
Registered User
Join Date: Jul 2010
Location: Janesville, WI
Posts: 664
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Re: Setting timing?
I run 14 initial on all mine with great results. I've never dynoed them but have great results my total winds up being 34-35
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