Tuning carb with a Vacuum Gauge - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Justins76 · 10-08-2015, 08:10 PM

When tuning a carb with a vacuum gauge, should the transmission be in Park or Drive?

cableguy0 · 10-08-2015, 08:29 PM

Quote:

Originally Posted by Justins76

When tuning a carb with a vacuum gauge, should the transmission be in Park or Drive?

Park. Being in gear puts the engine under load which will lower the vacuum readings.

RyansToy · 10-08-2015, 08:29 PM

The manual is in neutral, so I would think the auto should not be loaded (in gear).

prostreetC-10 · 10-08-2015, 09:05 PM

Quote:

Originally Posted by cableguy0

Park. Being in gear puts the engine under load which will lower the vacuum readings.

That and it also requires you to run along side the truck which can be tricky.

cableguy0 · 10-08-2015, 09:21 PM

Quote:

Originally Posted by prostreetC-10

That and it also requires you to run along side the truck which can be tricky.

Your supposed to stand on the bumper or sit in the engine bay. I thought that was required when working on an old truck.

prostreetC-10 · 10-08-2015, 09:28 PM

Quote:

Originally Posted by cableguy0

Your supposed to stand on the bumper or sit in the engine bay. I thought that was required when working on an old truck.

Hey on a serious note, have you seen those things that you almost lay against and they curve over the front of the truck. Looks like it would really save the back of the knees. Saw one on TRUCK U. I remember weekends where I was hunched over that truck for hours and could hardly walk the next day. I too am a fan of just climbing on into the bay and making yourself comfy! lol

cableguy0 · 10-08-2015, 09:33 PM

Quote:

Originally Posted by prostreetC-10

Hey on a serious note, have you seen those things that you almost lay against and they curve over the front of the truck. Looks like it would really save the back of the knees. Saw one on TRUCK U. I remember weekends where I was hunched over that truck for hours and could hardly walk the next day. I too am a fan of just climbing on into the bay and making yourself comfy! lol

Absolutely have used one. Its called a truck creeper. They are fine if your in the same spot for a long while but Im stubborn and move a lot. They do work well but for stuff where your constantly back and forth climbing up and down to grab another tool etc is worse than just being uncomfortable. Also if your drinking the required amount of beer you wont stay hunched for hours because between drinking the beer, getting the beer and going to pee you have plenty of time to stretch.

71_Burb · 10-11-2015, 01:49 AM

Just read the thread .... Great useful info that I'm gonna use over the weekend and make some tweeks ..

ranger danger · 10-17-2015, 10:24 AM

I picked up a vacuum gauge last week. Its an Ashcroft 1850. I plan on band clamping a hook on it so I can hang it from the hood. I hope its big enough!

prostreetC-10 · 10-17-2015, 01:53 PM

The threads below are so you can actually BOLT it to the hood! Kind of like the Pontiac GTO hood tach.

ranger danger · 10-17-2015, 02:01 PM

Quote:

Originally Posted by prostreetC-10

The threads below are so you can actually BOLT it to the hood! Kind of like the Pontiac GTO hood tach.

The threads below are for the vacuum line.

ranger danger · 10-17-2015, 02:14 PM

Ok I got the new gasket installed with a LIGHT layer of grease like suggested.
First is a pic of the old gasket, about construction paper thick.
Then the location I got vacuum from (off the manifold, next to the vacuum for the trans.)
Then a pic of the gauge at 1900 RPM's. Dead steady at 21.5"
Then a pic of the gauge at 700 RPM's. Vibrates between 18" and 18.5"

ranger danger · 10-17-2015, 02:16 PM

The new gasket is a Felpro thats about 1/4" thick.

ranger danger · 10-17-2015, 03:31 PM

Ok after slight adjustments to the carb air screws, the vacuum is vibrating between 18.9" and 19.1". Not to bad.

prostreetC-10 · 10-18-2015, 01:16 PM

Quote:

Originally Posted by ranger danger

The threads below are for the vacuum line.

Way to take the humor right out of it.......

prostreetC-10 · 10-18-2015, 01:19 PM

I'm sorry but that gauge is freaking hilarious. The guys on the space station said your vacuum is just under 22 hg. No matter if it works though!

ranger danger · 10-18-2015, 01:24 PM

Quote:

Originally Posted by prostreetC-10

I'm sorry but that gauge is freaking hilarious. The guys on the space station said your vacuum is just under 22 hg. No matter if it works though!

Ya its big but I can see it!

crazy longhorn · 10-18-2015, 09:56 PM

Quote:

Originally Posted by ranger danger

Ya its big but I can see it!

I love it....this old mans eyes can see it

Longhorn

ranger danger · 10-18-2015, 10:12 PM

Hanging under the hood of the truck, it looks like one of those clocks we used to have in school (45 years ago). You could see it from the back of the room. Every agonizing minute of it!!

crazy longhorn · 10-18-2015, 10:42 PM

Well, I have to ask....did it fix the problem? Longhorn

ranger danger · 10-19-2015, 05:53 AM

Quote:

Originally Posted by crazy longhorn

Well, I have to ask....did it fix the problem? Longhorn

Well it fixed the vacuum leak but, it did not fix the trans problem. Clinebarger suggested a few things that basically said its time for a trip to the trans shop. I broke the tachometer while replacing the wiper switch. I ordered a new one. Once it gets here and installed, off we go to visit the tranny boys!

prostreetC-10 · 10-19-2015, 12:47 PM

Quote:

Originally Posted by ranger danger

Ya its big but I can see it!

I used to laugh when guys couldn't read the LIST number on their Holley without glasses. I am now that guy!!

SierraMtns · 10-19-2015, 05:29 PM

I like watching these guys. Here is a video on tuning with vacuum gauge.

https://www.youtube.com/watch?v=X0uEMeDVxaA

10-08-2015, 08:10 PM	#26
Justins76 OutOfMyMind & I'llNeverKnowWhy Join Date: Apr 2004 Location: Another world, some other time Posts: 672	Re: Tuning carb with a Vacuum Gauge When tuning a carb with a vacuum gauge, should the transmission be in Park or Drive? __________________ -Justin-Out of my mind and I'll never know why 1976 Chevrolet Silverado C10 350 4bbl / TH350 Big10 longbed 1986 Pontiac Firebird T-Top 5.0L TPI 700R4 WS6 1992 Pontiac Firebird T-Top 5.0L TBI 700R4 My cardomain page I don't like to save, it's more fun to spend!!

10-08-2015, 08:29 PM	#28
RyansToy Registered User Join Date: Aug 2015 Location: Nova Scotia Canada Posts: 145	Re: Tuning carb with a Vacuum Gauge The manual is in neutral, so I would think the auto should not be loaded (in gear). __________________ 1968 GMC truck 910 Trim (Canadian) 127" WB 3 on the Three Trans (Saginaw SM330) 250 ci L6 Engine HEI ignition (early 80s L6)

10-11-2015, 01:49 AM	#33
71_Burb Registered User Join Date: Aug 2015 Location: Los Angeles Ca Posts: 34	Re: Tuning carb with a Vacuum Gauge Just read the thread .... Great useful info that I'm gonna use over the weekend and make some tweeks ..

10-17-2015, 10:24 AM	#34
ranger danger Registered User Join Date: Jan 2015 Location: Vacaville CA Posts: 896	Re: Tuning carb with a Vacuum Gauge I picked up a vacuum gauge last week. Its an Ashcroft 1850. I plan on band clamping a hook on it so I can hang it from the hood. I hope its big enough! Attached Images __________________ 1969 C20 Suburban "Rez Dog" Rebuild America one testicle at a time. US Army 1977-1979 12B Combat Engineer US Navy 1979-1983 Gunners Mate Guns (GMG) NRA Life Member Unrestrained Children in back seats cause Accidents. Unrestrained Accidents in back seats cause Children.

10-17-2015, 01:53 PM	#35
prostreetC-10 My Carbon Footprint Join Date: Oct 2008 Location: Orygun Posts: 5,527	Re: Tuning carb with a Vacuum Gauge The threads below are so you can actually BOLT it to the hood! Kind of like the Pontiac GTO hood tach. __________________ A quick "pedalfest" *Still getting loose (carb test)* 496 Initial fire up video!

10-17-2015, 02:14 PM	#37
ranger danger Registered User Join Date: Jan 2015 Location: Vacaville CA Posts: 896	Re: Tuning carb with a Vacuum Gauge Ok I got the new gasket installed with a LIGHT layer of grease like suggested. First is a pic of the old gasket, about construction paper thick. Then the location I got vacuum from (off the manifold, next to the vacuum for the trans.) Then a pic of the gauge at 1900 RPM's. Dead steady at 21.5" Then a pic of the gauge at 700 RPM's. Vibrates between 18" and 18.5" Attached Images __________________ 1969 C20 Suburban "Rez Dog" Rebuild America one testicle at a time. US Army 1977-1979 12B Combat Engineer US Navy 1979-1983 Gunners Mate Guns (GMG) NRA Life Member Unrestrained Children in back seats cause Accidents. Unrestrained Accidents in back seats cause Children.

10-17-2015, 02:16 PM	#38
ranger danger Registered User Join Date: Jan 2015 Location: Vacaville CA Posts: 896	Re: Tuning carb with a Vacuum Gauge The new gasket is a Felpro thats about 1/4" thick. __________________ 1969 C20 Suburban "Rez Dog" Rebuild America one testicle at a time. US Army 1977-1979 12B Combat Engineer US Navy 1979-1983 Gunners Mate Guns (GMG) NRA Life Member Unrestrained Children in back seats cause Accidents. Unrestrained Accidents in back seats cause Children.

10-17-2015, 03:31 PM	#39
ranger danger Registered User Join Date: Jan 2015 Location: Vacaville CA Posts: 896	Re: Tuning carb with a Vacuum Gauge Ok after slight adjustments to the carb air screws, the vacuum is vibrating between 18.9" and 19.1". Not to bad. __________________ 1969 C20 Suburban "Rez Dog" Rebuild America one testicle at a time. US Army 1977-1979 12B Combat Engineer US Navy 1979-1983 Gunners Mate Guns (GMG) NRA Life Member Unrestrained Children in back seats cause Accidents. Unrestrained Accidents in back seats cause Children.

10-18-2015, 01:19 PM	#41
prostreetC-10 My Carbon Footprint Join Date: Oct 2008 Location: Orygun Posts: 5,527	Re: Tuning carb with a Vacuum Gauge I'm sorry but that gauge is freaking hilarious. The guys on the space station said your vacuum is just under 22 hg. No matter if it works though! __________________ A quick "pedalfest" *Still getting loose (carb test)* 496 Initial fire up video!

10-18-2015, 10:12 PM	#44
ranger danger Registered User Join Date: Jan 2015 Location: Vacaville CA Posts: 896	Re: Tuning carb with a Vacuum Gauge Hanging under the hood of the truck, it looks like one of those clocks we used to have in school (45 years ago). You could see it from the back of the room. Every agonizing minute of it!! __________________ 1969 C20 Suburban "Rez Dog" Rebuild America one testicle at a time. US Army 1977-1979 12B Combat Engineer US Navy 1979-1983 Gunners Mate Guns (GMG) NRA Life Member Unrestrained Children in back seats cause Accidents. Unrestrained Accidents in back seats cause Children.

10-18-2015, 10:42 PM	#45
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Re: Tuning carb with a Vacuum Gauge Well, I have to ask....did it fix the problem? Longhorn __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears....

10-19-2015, 05:29 PM	#48
SierraMtns Registered User Join Date: Jun 2014 Location: Shingle Springs, CA Posts: 869	Re: Tuning carb with a Vacuum Gauge I like watching these guys. Here is a video on tuning with vacuum gauge. https://www.youtube.com/watch?v=X0uEMeDVxaA

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