should timing be set "by the book", or tweaked? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cell · 07-24-2006, 04:50 PM

My Haynes manual indicates my idle advance should be 4 degrees BTDC. Is that it? End of story? Or is this something which should be fine tuned?

I have heard horror stories of people shortening the life of their motors by "tweaking" their timing, and my 292 doesn't have any provision for knock sensing, so I don't see how I would even know if I had pushed things too far until my pistons start grenading...

jbon64 · 07-24-2006, 05:24 PM

"seat of the pants " has always been good to me. what seemed to work best for me was advance the timing till it just starts to ping , then back it off a degree or 2 . hope it works for you

ThatOneBlue67 · 07-24-2006, 07:52 PM

I keep mine at 4 deg. BTDC. Since tuning it to that (as apparently I was driving it with the wrong ignition timing for a short time) the motor stopped running so hot and held idle a LOT better. They're not performance or anything, you just gotta eye it at 4 deg BTDC.

cell · 08-22-2006, 06:04 PM

agreed ThatOneBlue67. I just set to 4 degrees advanced (as per recommendation in the Haynes manual), and it runs like a champ. engine warms up and then holds steady at the same temp.

76bonanza · 08-22-2006, 07:18 PM

Just depends on the motor but I always am of the rule the most intial advance it can take with out pinging will net the most power. I have Never had any heat issues or idle problems. Mine is a little more than stock maybe 330HP and it is set at 13 deg with nor problems.

Blazer1970 · 08-22-2006, 07:28 PM

Quote:

Originally Posted by 76bonanza

Just depends on the motor but I always am of the rule the most intial advance it can take with out pinging will net the most power. I have Never had any heat issues or idle problems. Mine is a little more than stock maybe 330HP and it is set at 13 deg with nor problems.

I agree, but I would not suggest this method unless you are sure that you know what spark knock sounds like. You can destroy an engine with uncontrolled or undetected detonation (pre-ignition, spark knock, knock, pinging, and detonation are all terms for the same thing). It will start by breaking the upper ring lands off of the pistons, then it will break compression rings leading to scored cylinder walls and sometimes it will put holes in pistons. Detonation will usually occur first when the engine is under load (almost lugging).

**special-K** · 08-23-2006, 06:48 AM

I use the up to ping/then back a bit method for great results.If you don`t hear a ping,it ai`nt pingin`.

cdowns · 08-23-2006, 07:05 AM

if you haven't degreed your cam so that you know exactly where the timing marker is in relation to TDC then it's just guesswork anyway is it not??

Premium72 · 08-23-2006, 09:35 AM

i had to play with mine a bit after intsalling the cam, was to advanced and i broke 2 starters before i figured it out. but you sound like your on the rite track .

jacobs · 08-23-2006, 09:43 AM

It depends on how the enging is built, fuel used, AND altitude. Where I live at 9,000 ft, with a factory engine, I must run 4 to 6 degrees aditional initial advance or it runs like a dog. Your ear is the best way to set the timing unless you're using an open exhaust and can't hear the enging ping.

07-24-2006, 04:50 PM	#1
cell Active Member Join Date: Nov 2005 Location: Austin Posts: 217	should timing be set "by the book", or tweaked? My Haynes manual indicates my idle advance should be 4 degrees BTDC. Is that it? End of story? Or is this something which should be fine tuned? I have heard horror stories of people shortening the life of their motors by "tweaking" their timing, and my 292 doesn't have any provision for knock sensing, so I don't see how I would even know if I had pushed things too far until my pistons start grenading...

07-24-2006, 05:24 PM	#2
jbon64 Registered User Join Date: Jan 2006 Location: sidney , illinois Posts: 312	Re: should timing be set "by the book", or tweaked? "seat of the pants " has always been good to me. what seemed to work best for me was advance the timing till it just starts to ping , then back it off a degree or 2 . hope it works for you __________________ hey.....smell my finger 64 nova wagon , 63 nova convertible

07-24-2006, 07:52 PM	#3
ThatOneBlue67 I survived Dead Man's Curve. Join Date: Apr 2006 Location: The Nine-Five-687 Posts: 389	Re: should timing be set "by the book", or tweaked? I keep mine at 4 deg. BTDC. Since tuning it to that (as apparently I was driving it with the wrong ignition timing for a short time) the motor stopped running so hot and held idle a LOT better. They're not performance or anything, you just gotta eye it at 4 deg BTDC. __________________ "The people should not be afraid of their government. The government should be afraid of it's people." "The Hurricane" 1967 Chevrolet C10 350 Eight Cylinder, 700R4 BowtieOverdrive *Cherry Bomb...* Disturbing the Peace Since 1968.

08-22-2006, 06:04 PM	#4
cell Active Member Join Date: Nov 2005 Location: Austin Posts: 217	Re: should timing be set "by the book", or tweaked? agreed ThatOneBlue67. I just set to 4 degrees advanced (as per recommendation in the Haynes manual), and it runs like a champ. engine warms up and then holds steady at the same temp.

08-22-2006, 07:18 PM	#5
76bonanza Senior Member Join Date: Mar 2003 Location: St robert Mo Posts: 2,001	Re: should timing be set "by the book", or tweaked? Just depends on the motor but I always am of the rule the most intial advance it can take with out pinging will net the most power. I have Never had any heat issues or idle problems. Mine is a little more than stock maybe 330HP and it is set at 13 deg with nor problems. __________________ 1968 c10 lowered 3" 4" 355/Th400 built by Hatfield racing in joplin MO Last edited by 76bonanza; 08-22-2006 at 07:18 PM.

08-23-2006, 06:48 AM	#7
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,859	Re: should timing be set "by the book", or tweaked? I use the up to ping/then back a bit method for great results.If you don`t hear a ping,it ai`nt pingin`. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

08-23-2006, 07:05 AM	#8
cdowns Senior Member Join Date: Jan 2003 Location: daytonabeach Posts: 22,956	Re: should timing be set "by the book", or tweaked? if you haven't degreed your cam so that you know exactly where the timing marker is in relation to TDC then it's just guesswork anyway is it not?? __________________ 71c-10 350/2004r/4:11 lowered3/4 longbed/dead by hurricane MEANING OF DEATH::::: SOMEBODY ELSE GETS YOUR STUFF DONT BELIEVE EVERYTHING YOU THINK TAKE MY ADVISE;I DON'T USE IT ANYWAY

08-23-2006, 09:35 AM	#9
Premium72 Registered User Join Date: Sep 2005 Location: Villa Rica Ga Posts: 889	Re: should timing be set "by the book", or tweaked? i had to play with mine a bit after intsalling the cam, was to advanced and i broke 2 starters before i figured it out. but you sound like your on the rite track . Last edited by Premium72; 08-23-2006 at 09:35 AM.

08-23-2006, 09:43 AM	#10
jacobs Registered User Join Date: Sep 2005 Location: 9000' Mountain Man Posts: 326	Re: should timing be set "by the book", or tweaked? It depends on how the enging is built, fuel used, AND altitude. Where I live at 9,000 ft, with a factory engine, I must run 4 to 6 degrees aditional initial advance or it runs like a dog. Your ear is the best way to set the timing unless you're using an open exhaust and can't hear the enging ping.

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