Who's headlights flicker at idle?? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

TIMSPEED · 08-07-2004, 11:41 PM

For some reason, if I set the idle on my truck to lower than 750-700rpm, the headlights flicker and the tach bounces. If I keep the idle (in gear) at 750-700, it's fine. Does anyone else's truck do this, or maybe is mine just not right? I'm thinking maybe the 65amp alternator might not be enough...but I mean, I'm ONLY running the headlights off of it...

*rage'nrat638* · 08-08-2004, 12:48 AM

SOUNDS LIKE YOUR TIMING IS SET TO HIGH

DOHOOOOOOOOOO

TIMSPEED · 08-08-2004, 06:04 AM

Quote:

Originally Posted by rage'nrat638

SOUNDS LIKE YOUR TIMING IS SET TO HIGH

My timing is set at 12º @ 800rpm, 36º @ 3000rpm.

NeCrOmAnCeR · 08-08-2004, 09:46 AM

I'm sure it was only a joke....
A higher amperade alt will not help in this case, it would actually make it worse. As the alternator speed slows down, the output voltage drops also. Assuming the alternator works fine at higher speeds it is working fine. It's just a fact of life. If you are trying to get the truck to sound more rumpity-rump at idle you will have to live with the flicking lights.

Grim Reaper · 08-08-2004, 10:26 AM

The copper got old and it's not as conductive.

Check your grounds to the core suport.

If they are all good then it hownestly is the 30-40ft of wire and 20 or so connections between the battery and the head lights are causing a voltage drop. To test that start the truck and turn on the head lights. Check the voltage at the battery and check the voltage at the healights. Your probably going to find a 1volt drop.

Painess sells a head light kit that puts some high quality relays and lager gage wires and pulls the power straight from the battery. It then uses the old wires as the trigger wires for the relays. BobbyK on the 67 forum has posted how to make your own kit on ck5.com and I'm sure he has also posted it here.
http://www.4crawler.com/4x4/CheapTri...adlights.shtml Is a little more info about the rewire.

*1972C10* · 08-08-2004, 01:32 PM

I idle most of mine at 1000

85Silveradoin04 · 08-09-2004, 07:54 PM

>>I idle most of mine at 1000

I'm assuming this is out of gear right? Thanks

Russell · 08-09-2004, 08:00 PM

Mine idles at about 700 rpm out of gear, and about 500 in gear, I found that it was clunking something nasty when I dropped it into gear when it used to idle about 800 - 900 in gear, and 1100 - 1200 out of gear. It idles very very smoothly at 500 rpm, and other than the headlights flickering a bit, it has no issues with it.

TIMSPEED · 08-09-2004, 08:34 PM

Quote:

Originally Posted by Russell

It idles very very smoothly at 500 rpm, and other than the headlights flickering a bit, it has no issues with it.

Your tach doesn't go crazy?

Russell · 08-09-2004, 09:01 PM

I don't have a tach in there right now, got one on the way, but I'll probally run the power wire to the tach directly from the battery with an inline fuse to get around this problem.

*1972C10* · 08-10-2004, 05:51 PM

Quote:

Originally Posted by 85Silveradoin04

>>I idle most of mine at 1000

I'm assuming this is out of gear right? Thanks

Yeah On a stock engine I may idle them a tad lower But All my hotrods i idle at 1000 I find that when you idle them low trying to get more cam sound they will have lower oil pressure. And dont seem to respond as well

gchemist · 08-10-2004, 08:26 PM

Get a bolt on 84-86 Camaro 94 amp alternator. I love mine.

75-K5 · 08-10-2004, 10:19 PM

It might be

but I have been told that setting idle around 1000 in P/N will keep the plugs cleaner. I like my automatic-equipped trucks to idle at 1000 in park and my manual rigs to idle in the 700-800 range in neutral. Can't do much about EFI trucks though, my '87 idles at 700 warm in park.

*1972C10* · 08-11-2004, 01:45 AM

Quote:

Originally Posted by gchemist

Get a bolt on 84-86 Camaro 94 amp alternator. I love mine.

Yeah ive been running one of them for a few years mine came off a 84 T/A With the H.o Im about to loose it due to a later model pulley swap Its been a good one always keeps me at about 14.5 volts at idle Ive acutally put new brushes in it due to wear and still going strong.

aliencheyenne · 08-11-2004, 02:30 AM

Cheaper than a new alt, run a couple of relays and have the headlights run off the battery. Wiring diagrams are all over the net, just goggle it.

TIMSPEED · 08-11-2004, 02:31 AM

Quote:

Originally Posted by aliencheyenne

Cheaper than a new alt, run a couple of relays and have the headlights run off the battery. Wiring diagrams are all over the net, just goggle it.

It's not just my headlights though...ALL the lights flicker. (Headlights, Interior Lights, Guage Lights) it doesn't bother me..it's just that my tach goes crazy. I may have to wire my tach to something other than the fuse block.

RockHQ · 08-11-2004, 05:11 PM

Quote:

Originally Posted by 75-K5

It might be

but I have been told that setting idle around 1000 in P/N will keep the plugs cleaner. I like my automatic-equipped trucks to idle at 1000 in park and my manual rigs to idle in the 700-800 range in neutral. Can't do much about EFI trucks though, my '87 idles at 700 warm in park.

I can assure you that any carbon deposits the spark plugs might accumulate during idling are burnt off during acceleration, so from that point of view it's BS. Unless you like to idle your cars for extended periods of time.

SanitysBane · 08-11-2004, 11:03 PM

mine never flicked, but i also has an altinator off of an 88, so not shure there

08-07-2004, 11:41 PM	#1
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	Who's headlights flicker at idle?? For some reason, if I set the idle on my truck to lower than 750-700rpm, the headlights flicker and the tach bounces. If I keep the idle (in gear) at 750-700, it's fine. Does anyone else's truck do this, or maybe is mine just not right? I'm thinking maybe the 65amp alternator might not be enough...but I mean, I'm ONLY running the headlights off of it... __________________ I have a few cars... See Them Here

08-08-2004, 10:26 AM	#5
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	The copper got old and it's not as conductive. Check your grounds to the core suport. If they are all good then it hownestly is the 30-40ft of wire and 20 or so connections between the battery and the head lights are causing a voltage drop. To test that start the truck and turn on the head lights. Check the voltage at the battery and check the voltage at the healights. Your probably going to find a 1volt drop. Painess sells a head light kit that puts some high quality relays and lager gage wires and pulls the power straight from the battery. It then uses the old wires as the trigger wires for the relays. BobbyK on the 67 forum has posted how to make your own kit on ck5.com and I'm sure he has also posted it here. http://www.4crawler.com/4x4/CheapTri...adlights.shtml Is a little more info about the rewire. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

08-09-2004, 08:00 PM	#8
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	Mine idles at about 700 rpm out of gear, and about 500 in gear, I found that it was clunking something nasty when I dropped it into gear when it used to idle about 800 - 900 in gear, and 1100 - 1200 out of gear. It idles very very smoothly at 500 rpm, and other than the headlights flickering a bit, it has no issues with it. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-09-2004, 09:01 PM	#10
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I don't have a tach in there right now, got one on the way, but I'll probally run the power wire to the tach directly from the battery with an inline fuse to get around this problem. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

08-10-2004, 08:26 PM	#12
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Get a bolt on 84-86 Camaro 94 amp alternator. I love mine. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

08-08-2004, 12:48 AM	#2
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	SOUNDS LIKE YOUR TIMING IS SET TO HIGH DOHOOOOOOOOOO

08-08-2004, 09:46 AM	#4
NeCrOmAnCeR Registered User Join Date: Feb 2004 Location: Hodgenville, Ky Posts: 735	I'm sure it was only a joke.... A higher amperade alt will not help in this case, it would actually make it worse. As the alternator speed slows down, the output voltage drops also. Assuming the alternator works fine at higher speeds it is working fine. It's just a fact of life. If you are trying to get the truck to sound more rumpity-rump at idle you will have to live with the flicking lights.

08-08-2004, 01:32 PM	#6
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	I idle most of mine at 1000

08-09-2004, 07:54 PM	#7
85Silveradoin04 Registered User Join Date: Jun 2004 Posts: 64	>>I idle most of mine at 1000 I'm assuming this is out of gear right? Thanks

08-10-2004, 10:19 PM	#13
75-K5 Bucket of Bolts Join Date: Dec 2003 Location: Anderson, Indiana Posts: 455	It might be but I have been told that setting idle around 1000 in P/N will keep the plugs cleaner. I like my automatic-equipped trucks to idle at 1000 in park and my manual rigs to idle in the 700-800 range in neutral. Can't do much about EFI trucks though, my '87 idles at 700 warm in park. __________________ This is the project that never ends, yes it goes on and on my friend....

08-11-2004, 02:30 AM	#15
aliencheyenne Registered User Join Date: May 2004 Location: L.A. Style Capital of the World Posts: 44	Cheaper than a new alt, run a couple of relays and have the headlights run off the battery. Wiring diagrams are all over the net, just goggle it.

08-11-2004, 11:03 PM	#18
SanitysBane Registered User Join Date: May 2004 Location: Lubbock, Texas Posts: 2,121	mine never flicked, but i also has an altinator off of an 88, so not shure there __________________ '96 Nissan Pathfinder '02 Firebird Trans Am. '88 K5 Blazer



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