Timing question... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

philobeddoe · 06-04-2015, 07:48 PM

I just set the idle to factory specs and advanced timing to about 10 degrees BTDC, factory specs calls for 8 degrees, will I be okay at 10? It seems to run smooth and peppy (for a 305 anyway). I have read that a little advanced is good regarding power and fuel economy. But, as long as there is no pinging or knocking. Thanks...

tinydb84 · 06-04-2015, 08:18 PM

Assuming you set it properly then 10 is fine.

1976gmc20 · 06-04-2015, 08:22 PM

I dunno, but when we moved from Colorado to Montana (big drop in altitude) in 1997, I set the 350 in my 1976 to factory specs for 3500' with a timing light, and it ran like crap

So I set it by ear and it has been purring ever since and no pinging

philobeddoe · 06-04-2015, 09:31 PM

Quote:

Originally Posted by 1976gmc20

I dunno, but when we moved from Colorado to Montana (big drop in altitude) in 1997, I set the 350 in my 1976 to factory specs for 3500' with a timing light, and it ran like crap

So I set it by ear and it has been purring ever since and no pinging

Posted via Mobile Device

philobeddoe · 06-04-2015, 09:31 PM

Yup, thats the way to do it sometimes! Amen.
Posted via Mobile Device

philobeddoe · 06-04-2015, 09:37 PM

If it feels and runs like it did the day at the dealership back in 1976, 1977 or whenever, then its perfect and proper. You just have to put yourself back in time a little and think how it ran then. Most of us on this forum should have a good idea of that.
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1976gmc20 · 06-04-2015, 10:43 PM

I retard the timing until it's chugging, then slowly advance until I get to the point where it seems to be running best.

There's usually a point beyond which it doesn't pick up rpm steadily. I find that point and then maybe back it up (retard) just a little bit. Honestly, it's more about where it just feels and sounds right.

That's what I like about these old engines: you really become a part of the process rather than just swapping some electronic parts and hoping it works.

philobeddoe · 06-05-2015, 11:07 AM

You are correct, there is a lot of truth to that! If it sounds good and feels smooth, something has to be correct in there. Can't do that with a 2015 Lexus!!

lindstromjd · 06-06-2015, 07:34 AM

In my experience, as long as you run better than 87 octane fuel, most engines are happier at 10-12 degrees BTDC.

1976gmc20 · 06-06-2015, 10:50 AM

It depends on the elevation. I think I used to set mine at -14 in the high mountains of Colorado. (when I bothered with a timing light)

But now I don't remember ever setting back my 73 during the couple years that I was in Alaska, nor did I muck with the 71 during a trip to the TX coast (but I did have to change the points and dist cap because of the salt air on the beach).

The 76 started pinging after we moved CO to MT, but it is a manual. Could be the slush-oh-matticks took care of that. Those TH350s never had any power anyway

**Gregski** · 06-06-2015, 11:10 AM

i run mine at 10 or as close to it as possible, remember those specs were for engines of 40 years ago they have worn majorly since

1976gmc20 · 06-06-2015, 01:39 PM

My 1976 only has 90-something thousand, compared to over 200K for the 1991 and 1989.

So forty years don't necessarily mean anything - for the pickup, anyway. For me those 40 years have been pretty hard

My timing is pretty slow anymore

06-04-2015, 07:48 PM	#1
philobeddoe Registered User Join Date: Mar 2015 Location: Brimfield, MA Posts: 91	Timing question... I just set the idle to factory specs and advanced timing to about 10 degrees BTDC, factory specs calls for 8 degrees, will I be okay at 10? It seems to run smooth and peppy (for a 305 anyway). I have read that a little advanced is good regarding power and fuel economy. But, as long as there is no pinging or knocking. Thanks... __________________ Philippians 4:8, Victory through pure thoughts. Last edited by philobeddoe; 06-04-2015 at 07:51 PM. Reason: spell check..

06-04-2015, 08:18 PM	#2
tinydb84 Registered User Join Date: Jul 2009 Location: San Jose Ca Posts: 2,871	Re: Timing question... Assuming you set it properly then 10 is fine. __________________ David Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991 My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985 Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557 Instagram: myfabguy

06-04-2015, 08:22 PM	#3
1976gmc20 Registered User Join Date: May 2015 Location: Montana Posts: 3,696	Re: Timing question... I dunno, but when we moved from Colorado to Montana (big drop in altitude) in 1997, I set the 350 in my 1976 to factory specs for 3500' with a timing light, and it ran like crap So I set it by ear and it has been purring ever since and no pinging __________________ Current/past Chevy/GMC trucks: 1958 Chevy C-60; 1965 GMC C-50; 1965 Chevy C-10; 1971 Chevy K-10; 1973 Chevy K-20; 1976 GMC C-20; 1977 Chevy C-10 Suburban; 1980 Chevy K-10; 1989 Chevy K1500; 1991 GMC V1500 Suburban; 2016 Chevy K2500 HD Other vehicles: 1988 Jeep XJ; 2011 Toyota 4Runner

06-04-2015, 09:31 PM	#5
philobeddoe Registered User Join Date: Mar 2015 Location: Brimfield, MA Posts: 91	Re: Timing question... Yup, thats the way to do it sometimes! Amen. Posted via Mobile Device

06-04-2015, 09:37 PM	#6
philobeddoe Registered User Join Date: Mar 2015 Location: Brimfield, MA Posts: 91	Re: Timing question... If it feels and runs like it did the day at the dealership back in 1976, 1977 or whenever, then its perfect and proper. You just have to put yourself back in time a little and think how it ran then. Most of us on this forum should have a good idea of that. Posted via Mobile Device

06-04-2015, 10:43 PM	#7
1976gmc20 Registered User Join Date: May 2015 Location: Montana Posts: 3,696	Re: Timing question... I retard the timing until it's chugging, then slowly advance until I get to the point where it seems to be running best. There's usually a point beyond which it doesn't pick up rpm steadily. I find that point and then maybe back it up (retard) just a little bit. Honestly, it's more about where it just feels and sounds right. That's what I like about these old engines: you really become a part of the process rather than just swapping some electronic parts and hoping it works. __________________ Current/past Chevy/GMC trucks: 1958 Chevy C-60; 1965 GMC C-50; 1965 Chevy C-10; 1971 Chevy K-10; 1973 Chevy K-20; 1976 GMC C-20; 1977 Chevy C-10 Suburban; 1980 Chevy K-10; 1989 Chevy K1500; 1991 GMC V1500 Suburban; 2016 Chevy K2500 HD Other vehicles: 1988 Jeep XJ; 2011 Toyota 4Runner

06-05-2015, 11:07 AM	#8
philobeddoe Registered User Join Date: Mar 2015 Location: Brimfield, MA Posts: 91	Re: Timing question... You are correct, there is a lot of truth to that! If it sounds good and feels smooth, something has to be correct in there. Can't do that with a 2015 Lexus!! __________________ Philippians 4:8, Victory through pure thoughts.

06-06-2015, 07:34 AM	#9
lindstromjd Gentleman Jim owner x2 Join Date: Oct 2010 Location: West Des Moines, IA Posts: 464	Re: Timing question... In my experience, as long as you run better than 87 octane fuel, most engines are happier at 10-12 degrees BTDC. __________________ 1975 GMC Gentleman Jim #1 -357 / 700r4 1975 GMC Gentleman Jim #2 -350 / TH350

06-06-2015, 10:50 AM	#10
1976gmc20 Registered User Join Date: May 2015 Location: Montana Posts: 3,696	Re: Timing question... It depends on the elevation. I think I used to set mine at -14 in the high mountains of Colorado. (when I bothered with a timing light) But now I don't remember ever setting back my 73 during the couple years that I was in Alaska, nor did I muck with the 71 during a trip to the TX coast (but I did have to change the points and dist cap because of the salt air on the beach). The 76 started pinging after we moved CO to MT, but it is a manual. Could be the slush-oh-matticks took care of that. Those TH350s never had any power anyway __________________ Current/past Chevy/GMC trucks: 1958 Chevy C-60; 1965 GMC C-50; 1965 Chevy C-10; 1971 Chevy K-10; 1973 Chevy K-20; 1976 GMC C-20; 1977 Chevy C-10 Suburban; 1980 Chevy K-10; 1989 Chevy K1500; 1991 GMC V1500 Suburban; 2016 Chevy K2500 HD Other vehicles: 1988 Jeep XJ; 2011 Toyota 4Runner

06-06-2015, 11:10 AM	#11
Gregski Post Whore Join Date: Aug 2014 Location: Sacramento, CA Posts: 10,882	Re: Timing question... i run mine at 10 or as close to it as possible, remember those specs were for engines of 40 years ago they have worn majorly since

06-06-2015, 01:39 PM	#12
1976gmc20 Registered User Join Date: May 2015 Location: Montana Posts: 3,696	Re: Timing question... My 1976 only has 90-something thousand, compared to over 200K for the 1991 and 1989. So forty years don't necessarily mean anything - for the pickup, anyway. For me those 40 years have been pretty hard My timing is pretty slow anymore __________________ Current/past Chevy/GMC trucks: 1958 Chevy C-60; 1965 GMC C-50; 1965 Chevy C-10; 1971 Chevy K-10; 1973 Chevy K-20; 1976 GMC C-20; 1977 Chevy C-10 Suburban; 1980 Chevy K-10; 1989 Chevy K1500; 1991 GMC V1500 Suburban; 2016 Chevy K2500 HD Other vehicles: 1988 Jeep XJ; 2011 Toyota 4Runner



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