Timing 350? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jkvette719 · 02-26-2003, 05:39 PM

I did do a search but i didnt see anything but stock numbers. I have a 78 350 Compcams 268H its a mild cam. Performer RPM heads. Just wondering where i should set the timing for best performance. Thanks Justin

PHOENIX · 02-26-2003, 05:44 PM

I think most guys run their timing at 10 Degrees BTDC (4 is stock, atleast on mine).
My engine seems to run best at 10 degrees BTDC (but my engine is stock).

82 Silverado 4X · 02-26-2003, 06:02 PM

I agree with Eddie. Start at about 10 BTDC and drive it a few days to see what it feels like ander varied conditions. Then if you want to you can bump it up a couple degrees to see if it hurts or helps the preformance.

jkvette719 · 02-26-2003, 06:53 PM

Okay I did that, Thanks now I have and accel dist w/ adj. vacum advance. How do I set that? Thanks

And man I got a valve to tight or something cause it has a surge to it.

GMC Jim · 02-26-2003, 09:26 PM

GM Tune up Spec Manual SD-100 has following 350 cu. in. light duty-emissions engine timing specs:-
Idle speed auto trans. 500 RPM, Ignition timing @ 8 degrees BTDC. At 2000 RPM; centrifigal advance at 12-16 degrees ( with vac advance hose disconnected and plugged). Total advance including vac advance @ 2000 RPM should be 28-36 degrees....

I use an adjustable timing lite.... Set the lite at 30-34 degrees and read the "0" mark on the crank damper/ pointer....use an accurate tachometer and have a friend hold the engine speed at 2000 RPM.
On my truck (402 engine) the vacumm advance unit was not functioning properly ; replaced it before the 2000 RPM timing specs and made quiet a difference in gas mileage and engine power.
Note that the range for the final 2000 RPM timing is 28-36 degrees....I would suggest you set it about 30-34 .... depending on gas octane you are using and other factors; adjust the timing toward the high end of the specs... but... before any detonation ( ping) is evident....
Hope this helps..........Jim

jkvette719 · 02-27-2003, 02:05 AM

Imnot getting any advance,,,,,but mine is adjustable so maybe i have to play with it. Thanks a ton...man at 500 RPM that feels like someones trying to tip the truck over lol...we go atleast 600. Thanks again

02-26-2003, 05:39 PM	#1
jkvette719 Registered User Join Date: Feb 2003 Location: Dayton, Ohio Posts: 12	Timing 350? I did do a search but i didnt see anything but stock numbers. I have a 78 350 Compcams 268H its a mild cam. Performer RPM heads. Just wondering where i should set the timing for best performance. Thanks Justin

02-26-2003, 05:44 PM	#2
PHOENIX Registered User Join Date: Oct 2002 Location: Phoenix, Arizona Posts: 4,703	I think most guys run their timing at 10 Degrees BTDC (4 is stock, atleast on mine). My engine seems to run best at 10 degrees BTDC (but my engine is stock). __________________ * AVOID: LOPER'S PERMORANCE / LOPERSPEED.COM OF PHOENIX, AZ & COTTMAN TRANSMISSION *

02-26-2003, 06:02 PM	#3
82 Silverado 4X Genuine Chevrolet Join Date: Feb 2003 Location: South West Pennsylvania. Posts: 582	I agree with Eddie. Start at about 10 BTDC and drive it a few days to see what it feels like ander varied conditions. Then if you want to you can bump it up a couple degrees to see if it hurts or helps the preformance. __________________ George 82 Silverado LWB 4x4 350 SM465 NP208 77 Chevrolet Blazer Chalet 400 TH350 NP203

02-26-2003, 09:26 PM	#5
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	GM Tune up Spec Manual SD-100 has following 350 cu. in. light duty-emissions engine timing specs:- Idle speed auto trans. 500 RPM, Ignition timing @ 8 degrees BTDC. At 2000 RPM; centrifigal advance at 12-16 degrees ( with vac advance hose disconnected and plugged). Total advance including vac advance @ 2000 RPM should be 28-36 degrees.... I use an adjustable timing lite.... Set the lite at 30-34 degrees and read the "0" mark on the crank damper/ pointer....use an accurate tachometer and have a friend hold the engine speed at 2000 RPM. On my truck (402 engine) the vacumm advance unit was not functioning properly ; replaced it before the 2000 RPM timing specs and made quiet a difference in gas mileage and engine power. Note that the range for the final 2000 RPM timing is 28-36 degrees....I would suggest you set it about 30-34 .... depending on gas octane you are using and other factors; adjust the timing toward the high end of the specs... but... before any detonation ( ping) is evident.... Hope this helps..........Jim __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

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02-26-2003, 06:53 PM	#4
jkvette719 Registered User Join Date: Feb 2003 Location: Dayton, Ohio Posts: 12	Okay I did that, Thanks now I have and accel dist w/ adj. vacum advance. How do I set that? Thanks And man I got a valve to tight or something cause it has a surge to it.

02-27-2003, 02:05 AM	#6
jkvette719 Registered User Join Date: Feb 2003 Location: Dayton, Ohio Posts: 12	Imnot getting any advance,,,,,but mine is adjustable so maybe i have to play with it. Thanks a ton...man at 500 RPM that feels like someones trying to tip the truck over lol...we go atleast 600. Thanks again



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