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I had this situation before many years ago. The left side of the motor hisses rhythmically and the smoke is a little darker. The idle is not perfectly smooth but not unacceptable and the car is drivable. Idle speed when warm has stayed as before. I have done the following: replaced the intake manifold gasket; took out and cleaned all jets. I also changed the emulsion tubes because I found out it had .1 instead of .2 which is what VWs are supposed to have. Carbs are Dellorto DRLA 40’s. I retorqued the bottom head studs and checked valve adjustment as well. I ran it without the belt to make sure it’s not fan related and it still makes the noise. Anyone else experienced this. I have checked on other forums such as the samba.com and cannot find much on something like that. I tried uploading a video but it gives me an error every time I try to upload it. Thank you in advance for any suggestions.

Link to video:

https://youtube.com/shorts/EHV...?si=GPnFjGqtgrOQKWZ9

Last edited by Impala
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My first choice would be a loose spark plug, too, but;

@Impala wrote: I have done the following:

Replaced the intake manifold gasket
(I'm assuming the manifold-to-head gasket, but just one or both?)

Took out and cleaned all jets.  That's always a good start, especially because it's so easy on Dells

I also changed the emulsion tubes because I found out it had .1 instead of .2 which is what VWs are supposed to have.  ???  That's news to me.  Besides, you engine probably isn't the same as a stock VW.  If it had been running well before with the old emulsion tubes, I would put them back in to eliminate another variable.  How long has this hissing been going on?

I would remove the carburetors and replace the carb-base-to-manifold gaskets.  A leak there could produce a rhythmic sound, depending on where the leak is.  Could be a hiss, could be a whistle but it will pulse with piston/valve action.  You're trying to find a leak that is probably one cylinder related, but'cha nevah know.   There is limited access around the carbs when installed, so wrapping a heavy rag around their bases to isolate the leak noise before you remove them, while possible, might be tough (but worth a try, for sure).  Another thing to try would be to get it idling when warm and stable, then pull one plug wire at a time from the distributor to see the result.  If one cylinder stumbles more than the others, that might point you toward where the leak is (but not guaranteed).

Carbs are Dellorto DRLA 40’s. I retorqued the bottom head studs and checked valve adjustment as well.  Also a good start but not my first choice.  What torque setting on the head nuts, just out of curiosity?  

I could be persuaded that this is a leaking exhaust gasket, so get under there and see if there is any carbon shadow blown outward from the exhaust flanges showing any leaks.  An exhaust leak is usually louder than an intake leak, on average.  If you can get it up on a lift while it is running it's easier to find an exhaust leak but that might be a big deal so look for carbon traces first.

**************************

Here's what I'm running on my 40mm Dells, set up by Dave Hoagland when he was still at Blackline Racing, for a  2,110cc,  MOFOCO big valve heads, port-matched heads and intake manifolds, Engle 120 cam, 1-5/8" header tubes (Berg headers).

The jet sizes are:

.45 idles

1.30 mains

160 air correctors  

.35 Accelerator pump jets

32mm Venturis  (These work GREAT on my 2,110 with 40mm Dells)

To show us a video, first, upload that video to Youtube, get it playing then click on the "Share" button and copy the link to it.  Then bring up a post reply on the SOC, click on the little movie icon in the menu bar at the top of the post and paste the link into the source window, then post the reply.  We should be able to see it after that.  You can delete it from Youtube after you get it fixed.

Buena Suerte....

Last edited by Gordon Nichols

My first choice would be a loose spark plug, too, but;

@Impala wrote: I have done the following:

Replaced the intake manifold gasket
(I'm assuming the manifold-to-head gasket, but just one or both?)

Took out and cleaned all jets.  That's always a good start, especially because it's so easy on Dells

I also changed the emulsion tubes because I found out it had .1 instead of .2 which is what VWs are supposed to have.  ???  That's news to me.  Besides, you engine probably isn't the same as a stock VW.  If it had been running well before with the old emulsion tubes, I would put them back in to eliminate another variable.  How long has this hissing been going on?

I would remove the carburetors and replace the carb-base-to-manifold gaskets.  A leak there could produce a rhythmic sound, depending on where the leak is.  Could be a hiss, could be a whistle but it will pulse with piston/valve action.  You're trying to find a leak that is probably one cylinder related, but'cha nevah know.   There is limited access around the carbs when installed, so wrapping a heavy rag around their bases to isolate the leak noise before you remove them, while possible, might be tough (but worth a try, for sure).  Another thing to try would be to get it idling when warm and stable, then pull one plug wire at a time from the distributor to see the result.  If one cylinder stumbles more than the others, that might point you toward where the leak is (but not guaranteed).

Carbs are Dellorto DRLA 40’s. I retorqued the bottom head studs and checked valve adjustment as well.  Also a good start but not my first choice.  What torque setting on the head nuts, just out of curiosity?  

I could be persuaded that this is a leaking exhaust gasket, so get under there and see if there is any carbon shadow blown outward from the exhaust flanges showing any leaks.  An exhaust leak is usually louder than an intake leak, on average.  If you can get it up on a lift while it is running it's easier to find an exhaust leak but that might be a big deal so look for carbon traces first.

**************************

Here's what I'm running on my 40mm Dells, set up by Dave Hoagland when he was still at Blackline Racing, for a  2,110cc,  MOFOCO big valve heads, port-matched heads and intake manifolds, Engle 120 cam, 1-5/8" header tubes (Berg headers).

The jet sizes are:

.45 idles

1.30 mains

160 air correctors  

.35 Accelerator pump jets

32mm Venturis  (These work GREAT on my 2,110 with 40mm Dells)

To show us a video, first, upload that video to Youtube, get it playing then click on the "Share" button and copy the link to it.  Then bring up a post reply on the SOC, click on the little movie icon in the menu bar at the top of the post and paste the link into the source window, then post the reply.  We should be able to see it after that.  You can delete it from Youtube after you get it fixed.

Buena Suerte....

I did replace the gasket on the left side; which is where the hissing comes from. Actually both gaskets had been replaced not too long ago but I did this one again to eliminate that variable.

The hissing came before I switched the emulsion tubes. The 9164.2 tubes, from what I’ve read on VW forums, are considered the ones for street use while the 9164.1 tubes are more for racing use. The .1s probably came with the set up for an Alfa Romeo. I have the following: 140 main jets  9164.2 emulsion tubes, 1.80 air correction, .60 idle jets. I believe that was the stock setup that CB Performance used back in the day when they sold them as per the Dellorto book by Tomlinson. Haven’t checked the Venturi sizes but it wouldn’t surprise me they were the 34s they came set up with from CB as well.

I retorqued the heads to between 23 -25 ft/lbs. (my torque wrench is the old style with the needle and the dial).

I don’t see any leaks or loose nuts or studs in the carb body itself but that is another possible place. I did get a full rebuild set for both carbs along with the .2 emulsion tubes from Gabriel in Italy; he has a store on EBay but prefer to not break them up until a full refurb is warranted. Maybe I can make a new gasket by tracing the old one. I have gasket material.

So the two things I need to verify now is that gasket in the carburetor and the spark plugs.

That set up you have is pretty peppy; nice displacement and good stuff in it; should haul ass!

I agree with you all; this is not the chirp. This thing has happened and has rectified itself not quite sure how a couple of times before and quite a few years ago. I will certainly check the spark plugs and do the compression tests as well. I first tried the obvious ones like the intake gasket. I hope it’s not a head stud; if it is it should be one of the top ones since I went over the bottom ones that are accessible and there were no signs of a broken one.

Update: a week ago I went to the garage to check on the spark plugs. On the 3-4 side I did notice them a little loose. Tightened #4 and #3 feeling pretty good about myself until I tried to put the spark plug wire back on #3 and feeling with my fingers I then realized the tip on #3 had broken off 😡. The space is so confined that even trying to use my tune up kit with multiple adapters with universal joints is a challenge and tips can break if you are not extremely careful. To add insult to injury the tip fell in the void around the spark plug hole and I could feel it with my index finger and was scared to death to even try to take the plug off fearing it could get into the combustion chamber. I tried to fish it out with tweezers; a shop vac and adhesive tape but I wasn’t successful.  It was late so I ceased operations for the day and decided to go back to change all the spark plugs this past Sunday. I decided to take the carburetors off so as to have better access; especially to try to fish out the spark plug tip that had broken off on #3.IMG_2688IMG_2687

Notice the side of the spark plug all blacked out; it definitely looks like it was loose; right now I can’t remember if this one is #3 or #4 but it is definitely the from the hissing left side.

IMG_2684

To make things worse the broken tip conveniently fell into never land; thankfully doesn’t interfere with the intake manifold. As I started checking the gap on the new plugs the .99 Chinesium gauge from AutoZone gave up the ghost and broke exactly in the area where we need it (between .024 and .030) so I had to stop by O’Reillys to get another one. Got everything buttoned up on the left side; I also checked the carburetor for anything loose or missing but found nothing wrong with it. On I went to #2 and it came out easily but I noticed it looks different to the ones on the left side. Looks like they were burning better; which leads me to believe that all your hunches about loose spark plugs were right.
IMG_2685IMG_2689

Accessibility to cylinder #1 proved even worse and it was late again so I decided to pack it up and maybe swing by tomorrow to do the same operation on that side. So far I’ve swapped all spark plugs except for #1. We’ll soon find out if I’ve solved this problem but things are pointing out to all your suggestions being right on the money. The hissing sound on the left side could very well be loose spark plugs, which, by being loose will also exhibit signs of an incomplete burn as compared to the one on cylinder #2. I will also swap the engine compartment seal which was disintegrating; I prepared another one years ago and coated with Flex Seal and stashed it for this very occasion. I just wish we could find the exact same Type IV Bus seal profile with a more durable material. That foam sucks big time.

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@DannyP posted:

Way back at the beginning of this thread, a couple posts in. Just saying...

Absolutely, my dear sir. The Piperato Oracle I call it 🤣. You never disappoint. It’s taken me longer to work on this because at this point I don’t have the good fortune of being able to keep my car in a clean garage right where I live; otherwise I would’ve dealt with this immediately. My next operation will be to remove the right carb and install spark plug #1 and the new engine compartment seal. Crossing my fingers that this fixes the problem. Merry Christmas to you and yours and to all our good friends here!

It’s tough doing maintenance on a car that’s garaged across town, and even harder under less than great conditions.  Trust me, I’ve been there, too, struggling around on uneven floors, in winter weather with ice cold tools and parts or not having the “right” tools that you left at home.  I’m too old to tolerate something like that today, but still have the scars and memories of simple, 30-minute jobs that turned into a multi-day effort of frustration.  

Even using the vacuum to suck up the loose bits, make sure you stuff something (rag, paper towel, soft rubber ball, etc.) into the intake ports on the head to insure that nothing is going down there until you’re ready to put the manifold back on.  A long time ago, I traced my intake manifold gasket shape onto a piece of cardboard and put those on my heads as soon as I pull an intake manifold off, just to prevent anything from falling in there.

As a vacuum tip, I have a small assortment of small diameter vinyl hoses (1/4” ID up to around 3/4” ID ) that I use to vacuum in tight places.  The tubes are over 12” long for a lot of flexibility and I just stuff the tubing into the shop vac hose and tape it in place with duct tape - Works great.  Smaller tubing will even fit down into the intake port if something is in there and the valve is closed.  

Last edited by Gordon Nichols

It’s tough doing maintenance on a car that’s garaged across town, and even harder under less than great conditions.  Trust me, I’ve been there, too, struggling around on uneven floors, in winter weather with ice cold tools and parts or not having the “right” tools that you left at home.  I’m too old to tolerate something like that today, but still have the scars and memories of simple, 30-minute jobs that turned into a multi-day effort of frustration.  

Even using the vacuum to suck up the loose bits, make sure you stuff something (rag, paper towel, soft rubber ball, etc.) into the intake ports on the head to insure that nothing is going down there until you’re ready to put the manifold back on.  A long time ago, I traced my intake manifold gasket shape onto a piece of cardboard and put those on my heads as soon as I pull an intake manifold off, just to prevent anything from falling in there.

As a vacuum tip, I have a small assortment of small diameter vinyl hoses (1/4” ID up to around 3/4” ID ) that I use to vacuum in tight places.  The tubes are over 12” long for a lot of flexibility and I just stuff the tubing into the shop vac hose and tape it in place with duct tape - Works great.  Smaller tubing will even fit down into the intake port if something is in there and the valve is closed.  

Absolutely my dear sir! The place is a pig sty and I share it with dirt, junk, pebbles on the floor, Florida cockroaches and reptiles, appliances, cabinets and plumbing fixtures. It is a storage for the landlord who owns various properties but it has a new roof and it is enclosed so the car is protected from the elements. Even after sweeping and cleaning the place up it gets back to that state fairly quickly. You might remember my posts here close to 20 years ago when I lived in a house and had more control of my working space, spare parts and tools. I miss those days and hopefully will get back to it before I kick the bucket. Meanwhile I do the best I can do which is manage under the circumstances. After 20 years of owning this particular car I still love it and it gives me the same thrills it did when I first got it. I am thankful for it. I wish you and yours and the rest of our great friends here a very Merry Christmas!!

make sure you stuff something (rag, paper towel, soft rubber ball, etc.) into the intake ports on the head to insure that nothing is going down there until you’re ready to put the manifold back on.


Although it was a mixed blessing, as it looked like I was about to have head gasket issues  

I’d just replaced a cracked intake rubber when I dropped one of the flat washers down the intake. Tried for 2 hrs to fish it out with a magnet with no luck.

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Update: Took out carb on the 1/2 bank and installed the spark plug on #1. The one that came off there looks like the one on #2.IMG_2706IMG_2705

That made me feel even better because it confirmed the theory of the loose plugs on bank 3/4. Well; got everything done; including the new engine compartment seal. Hate to break it to you but the Flex Seal idea tanked. The foam on the seal will disintegrate inside. I wonder why no one, like West Coast Metric has come with a better material for that profile. They suck royally. Anyway; started the car and the hissing continues. The Presto Pressure Cooker Saga continues….🙄

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