how do you get off the vacum advance? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

rusty ol' 69' · 03-31-2003, 09:04 PM

My truck likes to gulp the gas (or bog) when I blip the throttle. I just rebuilt the carb and it did this before I rebuilt it. The carb seems to work fine, but the bogging is still there. So I checked around this site a little and found out that my vacum advance could be the problem. So I took the line off my carb and blew into it and I did not see the advance move at all. Do I need to blow really hard to do this? Anyways, I figured I would try and take it off and mess with it. Well I got the cap and rotor off ( my truck has a points type distributor just to clarify things) and I can't seem to get to the screws. My question is: Do I have to take the points and everything else off to get to the vacum advance unit or can I do it without having to take everything apart? I don't want to have to adjust the points 'cause I don't have any feeler gauges just a crapy step spark plug gauge I got from kragen and that's why I'm asking.

Thanks,

Rusty

oldsub86 · 03-31-2003, 09:16 PM

I don't claim to be an expert on rebuilding distributors so someone else may point out errors that I may make here. However, here goes.
1. vacuum not pressure. Put the hose on the fitting on the advance unit on the distributor. Stick the other end in your mouth and suck on it rather than blowing. Does the mechanism move the plate on which the points are attached? If not then maybe the diaphram in the unit is open.

2. you may also want to check the mechanical advance. Is this an 8 or a 6? Are the springs and weights on top or under neath?
Are they attached. Does anything look worn?
How long have you had the truck? Has it always been like this or is this something new that is happening? IE could someone have changed the weights and or springs and in doing so buggered it up? There are kits out there to adjust these with different weight springs etc.

3. the last one I took apart was from a 302 F*rd. If I recall with it, I drove out a roll pin in the bottom gear and then the whole shaft slipped out of the housing so that I could get at the parts under the mounting plate.

rusty ol' 69' · 03-31-2003, 09:33 PM

1. Duh, vacum I should have known better. Boy do I feel dumb. I needed to suck not blow

I'll try that after dinner.

2. I have a V8 307 and the springs are on top right underneth the rotor. The springs are attached and I tried them and they spring open and closed fine and it all looks ok just a little dirty. When I bought the truck it was doing this, so it's nothing new just a matter of finding the problem.

3. I'll check the housing underneath for a roll pin. That'll make getting at it a lot more easier. I guess I'm being lazy and I just need to mark it and pull it then mess with it a little.

Anything else I might check for?

Thanks,

Rusty

jhow66 · 03-31-2003, 10:53 PM

To remove the can you have to push the plate counterclockwise and remove the screws at the same time.

jhow66 · 03-31-2003, 10:58 PM

As to the bog make sure the pump rod moves at the same time time as throttle shaft.Is it a 2 bar. Rochester?

rusty ol' 69' · 04-01-2003, 01:03 AM

Yeah, it's a two barrel rochester. So you can move the plate to get at the screws, I should have fiddle with it a little bit more thanks!

krue · 04-01-2003, 01:08 AM

Your engine should be running around 20" vacuum, unless you are superman you probably can't suck near that hard. I use a vacuum pump I bought to bleed brakes with to check vacuum operated parts.

Just my 2 cents.

$30 dollars at Sears, priceless if you have to bleed ur brakes all by ur lonesome!

rusty ol' 69' · 04-01-2003, 01:13 AM

lol that's funny! No I don't think I can suck that hard. Maybe I'll have to pickup a prostitute to give my motor a blow job

03-31-2003, 09:04 PM	#1
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	how do you get off the vacum advance? My truck likes to gulp the gas (or bog) when I blip the throttle. I just rebuilt the carb and it did this before I rebuilt it. The carb seems to work fine, but the bogging is still there. So I checked around this site a little and found out that my vacum advance could be the problem. So I took the line off my carb and blew into it and I did not see the advance move at all. Do I need to blow really hard to do this? Anyways, I figured I would try and take it off and mess with it. Well I got the cap and rotor off ( my truck has a points type distributor just to clarify things) and I can't seem to get to the screws. My question is: Do I have to take the points and everything else off to get to the vacum advance unit or can I do it without having to take everything apart? I don't want to have to adjust the points 'cause I don't have any feeler gauges just a crapy step spark plug gauge I got from kragen and that's why I'm asking. Thanks, Rusty __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!

03-31-2003, 09:16 PM	#2
oldsub86 Registered User Join Date: Dec 2002 Location: Canada Posts: 695	I don't claim to be an expert on rebuilding distributors so someone else may point out errors that I may make here. However, here goes. 1. vacuum not pressure. Put the hose on the fitting on the advance unit on the distributor. Stick the other end in your mouth and suck on it rather than blowing. Does the mechanism move the plate on which the points are attached? If not then maybe the diaphram in the unit is open. 2. you may also want to check the mechanical advance. Is this an 8 or a 6? Are the springs and weights on top or under neath? Are they attached. Does anything look worn? How long have you had the truck? Has it always been like this or is this something new that is happening? IE could someone have changed the weights and or springs and in doing so buggered it up? There are kits out there to adjust these with different weight springs etc. 3. the last one I took apart was from a 302 F*rd. If I recall with it, I drove out a roll pin in the bottom gear and then the whole shaft slipped out of the housing so that I could get at the parts under the mounting plate. __________________ 1968 Chevy - 292 with a powerglide

03-31-2003, 09:33 PM	#3
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	1. Duh, vacum I should have known better. Boy do I feel dumb. I needed to suck not blow I'll try that after dinner. 2. I have a V8 307 and the springs are on top right underneth the rotor. The springs are attached and I tried them and they spring open and closed fine and it all looks ok just a little dirty. When I bought the truck it was doing this, so it's nothing new just a matter of finding the problem. 3. I'll check the housing underneath for a roll pin. That'll make getting at it a lot more easier. I guess I'm being lazy and I just need to mark it and pull it then mess with it a little. Anything else I might check for? Thanks, Rusty __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!

03-31-2003, 10:53 PM	#4
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	To remove the can you have to push the plate counterclockwise and remove the screws at the same time. __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

03-31-2003, 10:58 PM	#5
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	As to the bog make sure the pump rod moves at the same time time as throttle shaft.Is it a 2 bar. Rochester? __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

04-01-2003, 01:03 AM	#6
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	Yeah, it's a two barrel rochester. So you can move the plate to get at the screws, I should have fiddle with it a little bit more thanks! __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!

04-01-2003, 01:08 AM	#7
krue Designated A-hole! Join Date: Mar 2003 Location: South Mississippi Posts: 36,450	Your engine should be running around 20" vacuum, unless you are superman you probably can't suck near that hard. I use a vacuum pump I bought to bleed brakes with to check vacuum operated parts. Just my 2 cents. $30 dollars at Sears, priceless if you have to bleed ur brakes all by ur lonesome! __________________ "If it ain't broke, fix it 'til it is!" Being stupid ain't illegal. We're Still Debt Free Except for the House!!! www.daveramsey.com 70 GMC SWB Stepside project "Green Booger" soon to be 6.0l/4l80e 93 S-10 "Poppaw's Truck"

04-01-2003, 01:13 AM	#8
rusty ol' 69' Grubbin' Join Date: Aug 2002 Location: Chico, CA Posts: 293	lol that's funny! No I don't think I can suck that hard. Maybe I'll have to pickup a prostitute to give my motor a blow job __________________ project rust attack 1969 Chevrolet LWB w/ 307. I got power steering now woohooooo!!!!!!!



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