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67rustavenger Samba Member

Joined: February 24, 2015 Posts: 10403 Location: Oregon
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Posted: Mon Jul 10, 2017 10:19 pm Post subject: Carb to intake manifold leak (Tutorial) |
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So there have been many posts over the years where the OP swears that the carb to intake flange was completely flat. I thought so too until tonight.....
This was after a little filing on the manifold flange.
Then I applied bluing to the manifold flange (redneck style) with a Sharpie.
I filed some more using the "draw file" method. Basically angling the file at a 45° angle to the piece that I am filing on. Please take note that I am doing this on my lap. Not with a vice. I can''t afford one at the moment
So after draw filing for 20 minutes. I can see the path that I need to take to get the flange flat.
Draw filing method.
Getting closer to completely flat.
I blued the flange once again.
This is the end result
Checked with a feeler gauge for flatness.
I hope this is helpful to those that think their carb to manifold is good when it is not.
Sadly the before pic didn't load. But you get the idea. Hopefully.
Good Luck. _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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andk5591 Samba Member

Joined: August 29, 2005 Posts: 16777 Location: State College, PA
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Posted: Tue Jul 11, 2017 5:16 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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That was nice...And a very common problem. Another option that I have used is to make a new gasket out of heavy gasket paper if its not real bad and I am not planning on removing the intake. _________________ D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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Zundfolge1432  Samba Member
Joined: June 13, 2004 Posts: 12542
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Posted: Tue Jul 11, 2017 5:51 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Very nice thanks, heater box flanges also need checked same way. A really nice high quality carb base gasket available here, proprietor had them made out of desperation because of ? You guessed it. Shitty aftermarket gaskets. He priced them reasonable, get several @
www.bughaus.com |
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Sharp64 Samba Member

Joined: August 27, 2015 Posts: 5304 Location: Central Florida
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Posted: Tue Jul 11, 2017 6:03 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Doesn't the gasket accommodate for that minor of a variance? _________________ 1960 Indigo Blue Ragtop (Blue Barry)
1967 Ghia
1985 Westy Money Pit
“...some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.” - Michael Caine |
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Zundfolge1432  Samba Member
Joined: June 13, 2004 Posts: 12542
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Posted: Tue Jul 11, 2017 6:34 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Sharp64 wrote: |
Doesn't the gasket accommodate for that minor of a variance? |
Depends on the gasket, the low quality crap out there doesn't always work. Take a look at the gasket I suggested, there's a pic up on the website, looks stout. |
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bluebus86 Banned
Joined: September 02, 2010 Posts: 11075
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Posted: Tue Jul 11, 2017 7:13 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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you think the manifold is not flat, wait till you check the carb base! the carbbases I have found to usually be more warped than the manifolds.
Use of extra fat gaskets can result in more warpage of the carb flange. use care, dont over tighten to seal a leak from a warped flange(s) as that can cause even more warpage. _________________ Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022
Last edited by bluebus86 on Tue Jul 11, 2017 7:50 am; edited 1 time in total |
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Sharp64 Samba Member

Joined: August 27, 2015 Posts: 5304 Location: Central Florida
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Posted: Tue Jul 11, 2017 7:22 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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I guess I always just thought the gasket absorbed fuel/moisture and swelled to fill any slight unevenness. Based on those pics, it's what? .001? I'm not arguing, just surprised that this would cause any discernible issue. Learn something new I guess. _________________ 1960 Indigo Blue Ragtop (Blue Barry)
1967 Ghia
1985 Westy Money Pit
“...some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.” - Michael Caine |
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buguy Samba Member

Joined: November 17, 2003 Posts: 4915 Location: Port Orange, FL
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Posted: Tue Jul 11, 2017 9:57 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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I agree that a gasket would probably seal it. But now there will be no guesswork. |
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EverettB  Administrator

Joined: April 11, 2000 Posts: 70937 Location: Phoenix 602
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Posted: Tue Jul 11, 2017 10:07 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Zundfolge1432 wrote: |
Sharp64 wrote: |
Doesn't the gasket accommodate for that minor of a variance? |
Depends on the gasket, the low quality crap out there doesn't always work. Take a look at the gasket I suggested, there's a pic up on the website, looks stout. |
Yes, some of the ones that come in cheap rebuild kits are really thin compared to "real" ones.
Sharp64 wrote: |
I guess I always just thought the gasket absorbed fuel/moisture and swelled to fill any slight unevenness. Based on those pics, it's what? .001? I'm not arguing, just surprised that this would cause any discernible issue. Learn something new I guess. |
I haven't seen it swell, at least not some huge amount, but they do deform to the shape of the carb. base so when you remove it, you see the pattern of ridges from the bottom of the carb. _________________ How to Post Photos
Everett Barnes - [email protected] | My wanted ads
"Water is the only drink for a wise man" | "Communication prevents complaints"
Stop dead photo links! Post your photos to The Samba Gallery! |
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Sharp64 Samba Member

Joined: August 27, 2015 Posts: 5304 Location: Central Florida
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Posted: Tue Jul 11, 2017 6:35 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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EverettB wrote: |
Zundfolge1432 wrote: |
Sharp64 wrote: |
Doesn't the gasket accommodate for that minor of a variance? |
Depends on the gasket, the low quality crap out there doesn't always work. Take a look at the gasket I suggested, there's a pic up on the website, looks stout. |
Yes, some of the ones that come in cheap rebuild kits are really thin compared to "real" ones.
Sharp64 wrote: |
I guess I always just thought the gasket absorbed fuel/moisture and swelled to fill any slight unevenness. Based on those pics, it's what? .001? I'm not arguing, just surprised that this would cause any discernible issue. Learn something new I guess. |
I haven't seen it swell, at least not some huge amount, but they do deform to the shape of the carb. base so when you remove it, you see the pattern of ridges from the bottom of the carb. |
Cool. Good info to know and one more vacuum leak to look for. Something I'll definitely look at from now on. _________________ 1960 Indigo Blue Ragtop (Blue Barry)
1967 Ghia
1985 Westy Money Pit
“...some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn.” - Michael Caine |
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andk5591 Samba Member

Joined: August 29, 2005 Posts: 16777 Location: State College, PA
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Posted: Wed Jul 12, 2017 7:04 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Once again - if not real bad, I have a roll of 1/16" gasket paper. Get a cheap set of hole punches and you can make them as needed. I have various thicknesses of gasket material and make a lot of my own gaskets if I don't have the correct one in stock.
https://www.harborfreight.com/9-piece-hollow-punch-set-3838.html _________________ D-Dubya Manx clone 1914. Ex wifes car.
Rosie 65 bug - My mostly stock daily driver.
Woodie 69 VW woodie (Hot VWs 7/12).
"John's car" 64 VW woodie - The first ever
Maxine 61 Cal-look bug - Ex-wifes car.
66 bug project - Real patina & Suby conversion
There's more, but not keeping them... |
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Cusser Samba Member

Joined: October 02, 2006 Posts: 32485 Location: Hot Arizona
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Posted: Wed Jul 12, 2017 8:54 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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andk5591 wrote: |
Once again - if not real bad, I have a roll of 1/16" gasket paper. Get a cheap set of hole punches and you can make them as needed. I have various thicknesses of gasket material and make a lot of my own gaskets if I don't have the correct one in stock.
https://www.harborfreight.com/9-piece-hollow-punch-set-3838.html |
If I ever do need to make a gasket, I typically trace first, then drill the holes out on my drill press. Third is that I actually do the cutting.
Right now I'm running homemade rubberized gasket (from O'Reilly) under the Weber carb and adapter on my 1988 Mazda truck, as back in 2011 when I rebuilt its engine and had vacuum leak, it would've taken about a week to obtain from California or New York (now I have a set of new as spare). _________________ 1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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67rustavenger Samba Member

Joined: February 24, 2015 Posts: 10403 Location: Oregon
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Posted: Wed Jul 12, 2017 6:29 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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To all of the follow up posters. Thank you for the input.
I created this thread to show how with simple tools and methods you can get your carb intake flange flat for a good sealing surface.
My intent surely was not to debate the merits of carb gasket quality. Gasket quality has been covered on the samba many times.
I did check the lower carb flange last night and it's flat. So I'm good in that respect.
I did use an HF file It was what I had on hand. The correct choice of file should have been a "Mill Bastard" instead if the cross cut file I used. I would have had a better flange finish using the Mill Bastard.
Zundfolge1432 - I wish I would have posted this three weeks ago. Your suggestion to do the same on the exhaust flanges caused a lighting bolt to pass through my head. I installed a poor fitting muffler with an ill fitting flange on the #4 exhaust port. It fit like shit. Oh well  _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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bluebus86 Banned
Joined: September 02, 2010 Posts: 11075
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Posted: Wed Jul 12, 2017 7:49 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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67rustavenger wrote: |
To all of the follow up posters. Thank you for the input.
I created this thread to show how with simple tools and methods you can get your carb intake flange flat for a good sealing surface.
My intent surely was not to debate the merits of carb gasket quality. Gasket quality has been covered on the samba many times.
I did check the lower carb flange last night and it's flat. So I'm good in that respect.
I did use an HF file It was what I had on hand. The correct choice of file should have been a "Mill Bastard" instead if the cross cut file I used. I would have had a better flange finish using the Mill Bastard.
Zundfolge1432 - I wish I would have posted this three weeks ago. Your suggestion to do the same on the exhaust flanges caused a lighting bolt to pass through my head. I installed a poor fitting muffler with an ill fitting flange on the #4 exhaust port. It fit like shit. Oh well  |
Same technique my Dad taught me 40 years ago when hed repair the family Bug, smart guy. _________________ Help Prevent VW Engine Fires, see this link.....Engine safety wire information
Stop introducing dirt into your oil when adjusting valves ... https://www.thesamba.com/vw/forum/viewtopic.php?t=683022 |
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Zundfolge1432  Samba Member
Joined: June 13, 2004 Posts: 12542
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Posted: Thu Jul 13, 2017 9:16 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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67rustavenger wrote: |
To all of the follow up posters. Thank you for the input.
I created this thread to show how with simple tools and methods you can get your carb intake flange flat for a good sealing surface.
My intent surely was not to debate the merits of carb gasket quality. Gasket quality has been covered on the samba many times.
I did check the lower carb flange last night and it's flat. So I'm good in that respect.
I did use an HF file It was what I had on hand. The correct choice of file should have been a "Mill Bastard" instead if the cross cut file I used. I would have had a better flange finish using the Mill Bastard.
Zundfolge1432 - I wish I would have posted this three weeks ago. Your suggestion to do the same on the exhaust flanges caused a lighting bolt to pass through my head. I installed a poor fitting muffler with an ill fitting flange on the #4 exhaust port. It fit like shit. Oh well  |
I'd like to take credit for that but actually wcfvw69 Bill reminded me of this couple of months ago and also said check heat riser flange too. Basically all the flanges could be warped now 40-50 years of hard use. Thanks Bill.  |
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67rustavenger Samba Member

Joined: February 24, 2015 Posts: 10403 Location: Oregon
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Posted: Thu Jul 13, 2017 1:29 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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The carb was test fit last night. I thought that was ok. Wrong!
I'll do the write up when I get off work this evening. _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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67rustavenger Samba Member

Joined: February 24, 2015 Posts: 10403 Location: Oregon
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Posted: Thu Jul 13, 2017 5:24 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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So like I typed above. I test fit the carb last night after checking the flange was flat using a feeler gauge on edge from the front to back along the line of the studs. It looked ok.
So I placed the carb on the intake flange without a gasket and found the left and right sides were terribly warped. No wonder the car came with an H30/31 on the engine.
I removed the throttle are and the accel pump so the flange would sit flat.
I got out my piece of glass and sand paper to sand the carb base flat again.
Applied the redneck bluing again to track my progress.
I first sanded with 80grt. until the bluing was gone and the carb base was flat.
This is how much material had to be sanded off to get the base flat.
I applied the bluing again and changed to 150grt. paper. After 8 swipes on the sand paper. This is the result.
This is the final fit after sanding. Much better. Oh and no gasket would have helped this carb seal at the intake flange.
This took all of half an hour to 45 minutes to complete. For me the end result is satisfying. And the best part was the cost to do this $0.00.
Good Luck. _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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heimlich  VWNOS.com

Joined: November 20, 2016 Posts: 7272 Location: Houston, Texas
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Posted: Thu Jul 13, 2017 7:57 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Nice write up. Is there anyway to flatten these things out a little easier? I've been using a flat sanding pad and running the flange against it.
Is there a flange on these cars that doesn't get warped? I now check all of mine when working on my engines. |
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wcfvw69 Samba Purist

Joined: June 10, 2004 Posts: 13640 Location: Arizona
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Posted: Thu Jul 13, 2017 10:37 pm Post subject: Re: Carb to intake manifold leak (Tutorial) |
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Zundfolge1432 wrote: |
67rustavenger wrote: |
To all of the follow up posters. Thank you for the input.
I created this thread to show how with simple tools and methods you can get your carb intake flange flat for a good sealing surface.
My intent surely was not to debate the merits of carb gasket quality. Gasket quality has been covered on the samba many times.
I did check the lower carb flange last night and it's flat. So I'm good in that respect.
I did use an HF file It was what I had on hand. The correct choice of file should have been a "Mill Bastard" instead if the cross cut file I used. I would have had a better flange finish using the Mill Bastard.
Zundfolge1432 - I wish I would have posted this three weeks ago. Your suggestion to do the same on the exhaust flanges caused a lighting bolt to pass through my head. I installed a poor fitting muffler with an ill fitting flange on the #4 exhaust port. It fit like shit. Oh well  |
I'd like to take credit for that but actually wcfvw69 Bill reminded me of this couple of months ago and also said check heat riser flange too. Basically all the flanges could be warped now 40-50 years of hard use. Thanks Bill.  |
OP, nice work and pictures of how you accomplished this. These are the fine details that are often overlooked when fitting carbs or exhausts. I was chasing a self inflicted exhaust leak on an engine. I finally pressured the exhaust system with a clean wet/dry vac. I sprayed all the connections with soapy water. The exhaust was new and had been installed w/all new exhaust gaskets. EVERY joint looked like a bubble making machine! As soon as I saw that, I was reminded of my Dad telling me years ago to make sure the flanges are flat.
The muffler was removed as were the heater boxes. The heater box flanges and intake manifold flanges were seriously warped and required lots of time to flatten them again w/a big file. After bolting it all back together, the joints passed the pressured soapy water test and the engine was quiet.  _________________ Contact me at [email protected]
Follow me on instagram @sparxwerksllc
40+ years of VW repair, and VW parts and vehicle restoration experience.
The Samba member since 2004.
**Now rebuilding throttle bodies for VW's and Porsche's**
**Restored German Bosch distributors for sale or I can restore yours**
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**Restored Porsche distributors or I can restore yours** |
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67rustavenger Samba Member

Joined: February 24, 2015 Posts: 10403 Location: Oregon
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Posted: Fri Jul 14, 2017 5:40 am Post subject: Re: Carb to intake manifold leak (Tutorial) |
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kawfee wrote: |
Nice write up. Is there anyway to flatten these things out a little easier? I've been using a flat sanding pad and running the flange against it. |
Sure there are easier and less labor intensive methods to get the flanges true.
The whole point of the methods that I applied was to demonstrate that this can accomplished with hand tools. I'd like to have a belt sander(hint) for this work. But I don't have the funds or the space to keep one.
These cars are old. After many years of careless hacks working on them the flanges get warped and need attention. _________________ I have learned over the years.
Cheap parts are gonna disappoint you.
Buy Once, Cry Once!
There's never enough time to do it right the first time. But there's always enough time to do it thrice.
GFY's Xevin and VW_Jimbo! |
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