40btdc??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ocbaud · 06-16-2004, 08:38 PM

i picked up a dial back timing light tonight. hooked it up, set it to 0 like it said to do, and it is reading WAY off.

**swervin ervin** · 06-16-2004, 08:46 PM

Did you remove and plug the vacuum advance hose? The way it works is, aim it at the timing tab with it set to zero on the light. Now slowly turn the knob until the pointer is at zero at the tab. Read the dial and this is what your initial advance is.

ocbaud · 06-16-2004, 08:47 PM

yes, vacuum hose is capped off.

what about problems with dial back timing lights and msd systems that i've heard about?

**swervin ervin** · 06-16-2004, 08:50 PM

Nothing I know of.

Sounds like your timing tab isn't correct for your balancer. If it's not right, the marks are 2-1/8" difference between the balancer made for a tab up top over one made for the tab toward the drivers side.

An 8" balancer is 25.12" in circumference. So to see how many degrees it would be off if you have the wrong balancer/pointer we do this.

BTW, just to make this clear, 8" x 3.14" = 25.12".

Now we have 360 degrees in a circle, so 360/25.12 = 14.33 or there abouts. So this means we have 14.33 degrees in one inch of an 8" balancer. So if it's off 2-1/8", you would be off, 14.33 x 2.125" = 30.45 degrees. So, if your balancer and pointer don't match, and you say you have 37 degrees of advance now, this means to me you really have 6.5 degrees, right?

If you want to check it, use a cloth tape, like a sewing tape, and measure from the factory mark on the balancer 2-1/8" clockwise, from the front of the engine. Put a scratch mark there and maybe some white paint. Now see what it says when you check the timing with the light. If it's wrong parts and you have been getting 37 degrees before, you should be right around 6 - 7 degrees btdc.

Edit: I copied and pasted this. Since you say 40 degrees. it would really be around 9.5 degrees if it's the wrong balancer.

ocbaud · 06-16-2004, 08:52 PM

when i follow the instructions you gave in your first post, it would mean i have 50 degrees of advance.

the timing tab and balancer is correct. i set the timing last time with a friends normal, non dial back timing light.

**swervin ervin** · 06-16-2004, 08:56 PM

If you turn the dial to zero and point it at the timing tab, what do you get? Rotate the dial while pointing it at the tab until it gets to zero on the timing tab. Read the dial, it should be what you first saw at the tab. If so, the light is right.

ocbaud · 06-16-2004, 08:58 PM

when the dial is at 0, the marks on the balancer say 45.

when the balancer is at 0, the dial says 50..

so mike, tell me what i need to do to fix all my problems

**swervin ervin** · 06-16-2004, 09:14 PM

Damned if I know how to do that.

Borrow your friends light again and see what his says.

Are you sure the balancer/pointer is right? Only way to find out is with a piston stop. You remove number one plug and screw in the stop. Slowly rotate the engine clockwise from front until it makes contact with the stop. Do this slow (and by hand) so you don't damage the piston. Anyway, when it makes contact, make a mark on the balancer at the zero on the pointer. Now rotate the engine counterclockwise until it contacts the stop. Make a mark on the balancer again at zero on the pointer. Center ways between these two marks in TDC. Is your TDC mark on the balancer here? If not, the balancer is off or you have the wrong balancer/pointer combo.

ocbaud · 06-16-2004, 09:20 PM

i did that last time when i set the initial timing with my friends light. i bought timing tape and everything for it.

i dont see a way for it to be off so much.

TIMSPEED · 06-16-2004, 10:58 PM

You got it hooked to the #1 spark plug wire right? I don't see how it could possibly even RUN with that much timing at idle...

plumbcut · 06-17-2004, 01:11 AM

it will definately run with that much timing...

ocbaud · 06-17-2004, 01:17 AM

Quote:

Originally Posted by plumbcut

it will definately run with that much timing...

but not as good as it is right now

*1972C10* · 06-17-2004, 03:56 AM

You dont have to have a piston stop thats why god invented screwdrivers run the piston up with the screwdriver in the hole and when you feel it coming up keep turning it untill it stops and you may feel it slightly go down thats TDC or close enuff to see if you have the right pointer for your balancer.

06-16-2004, 08:46 PM	#2
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Did you remove and plug the vacuum advance hose? The way it works is, aim it at the timing tab with it set to zero on the light. Now slowly turn the knob until the pointer is at zero at the tab. Read the dial and this is what your initial advance is. __________________ Mike 1985 Chevy C-10

06-16-2004, 08:50 PM	#4
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Nothing I know of. Sounds like your timing tab isn't correct for your balancer. If it's not right, the marks are 2-1/8" difference between the balancer made for a tab up top over one made for the tab toward the drivers side. An 8" balancer is 25.12" in circumference. So to see how many degrees it would be off if you have the wrong balancer/pointer we do this. BTW, just to make this clear, 8" x 3.14" = 25.12". Now we have 360 degrees in a circle, so 360/25.12 = 14.33 or there abouts. So this means we have 14.33 degrees in one inch of an 8" balancer. So if it's off 2-1/8", you would be off, 14.33 x 2.125" = 30.45 degrees. So, if your balancer and pointer don't match, and you say you have 37 degrees of advance now, this means to me you really have 6.5 degrees, right? If you want to check it, use a cloth tape, like a sewing tape, and measure from the factory mark on the balancer 2-1/8" clockwise, from the front of the engine. Put a scratch mark there and maybe some white paint. Now see what it says when you check the timing with the light. If it's wrong parts and you have been getting 37 degrees before, you should be right around 6 - 7 degrees btdc. Edit: I copied and pasted this. Since you say 40 degrees. it would really be around 9.5 degrees if it's the wrong balancer. Last edited by swervin ervin; 06-16-2004 at 08:53 PM.

06-16-2004, 10:58 PM	#10
TIMSPEED Join Date: Jan 2003 Location: Modesto, CA Posts: 1,321	You got it hooked to the #1 spark plug wire right? I don't see how it could possibly even RUN with that much timing at idle... __________________ I have a few cars... See Them Here

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06-16-2004, 08:38 PM	#1
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	40btdc??? i picked up a dial back timing light tonight. hooked it up, set it to 0 like it said to do, and it is reading WAY off.

06-16-2004, 08:47 PM	#3
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	yes, vacuum hose is capped off. what about problems with dial back timing lights and msd systems that i've heard about?

06-16-2004, 08:52 PM	#5
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	when i follow the instructions you gave in your first post, it would mean i have 50 degrees of advance. the timing tab and balancer is correct. i set the timing last time with a friends normal, non dial back timing light.

06-16-2004, 08:56 PM	#6
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	If you turn the dial to zero and point it at the timing tab, what do you get? Rotate the dial while pointing it at the tab until it gets to zero on the timing tab. Read the dial, it should be what you first saw at the tab. If so, the light is right.

06-16-2004, 08:58 PM	#7
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	when the dial is at 0, the marks on the balancer say 45. when the balancer is at 0, the dial says 50.. so mike, tell me what i need to do to fix all my problems

06-16-2004, 09:14 PM	#8
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	Damned if I know how to do that. Borrow your friends light again and see what his says. Are you sure the balancer/pointer is right? Only way to find out is with a piston stop. You remove number one plug and screw in the stop. Slowly rotate the engine clockwise from front until it makes contact with the stop. Do this slow (and by hand) so you don't damage the piston. Anyway, when it makes contact, make a mark on the balancer at the zero on the pointer. Now rotate the engine counterclockwise until it contacts the stop. Make a mark on the balancer again at zero on the pointer. Center ways between these two marks in TDC. Is your TDC mark on the balancer here? If not, the balancer is off or you have the wrong balancer/pointer combo.

06-16-2004, 09:20 PM	#9
ocbaud Garage Queen Material Join Date: Oct 2002 Location: USA Posts: 4,129	i did that last time when i set the initial timing with my friends light. i bought timing tape and everything for it. i dont see a way for it to be off so much.

06-17-2004, 01:11 AM	#11
plumbcut california fill Join Date: Apr 2004 Location: Sunny So-Cal Posts: 694	it will definately run with that much timing...

06-17-2004, 03:56 AM	#13
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	You dont have to have a piston stop thats why god invented screwdrivers run the piston up with the screwdriver in the hole and when you feel it coming up keep turning it untill it stops and you may feel it slightly go down thats TDC or close enuff to see if you have the right pointer for your balancer.



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