Hissing Again

I got back from NOLA yesterday for a week and got the Speedster running this morning and used it for a while. Now it has developed a rhythmic hissing sound by the right side (carb?). I had a hissing situation before but the car started idling roughly with black smoke coming out of the tailpipes. Turned out to be the intake manifold to head gasket but on the left side carb. I'm wondering (if it is the same thing) why the car is idling fine and not blowing black smoke this time. Any of you have previous experiences with this?

Loose or bad plug, maybe?

I doubt it; we put them in not ultra tight but decently tight (have to be careful with these aluminum heads)but I'll definitely check tomorrow.

If you suspect an intake leak, you should spray carburetor cleaner on your running engine in the area where you hear the noise.

If there is an intake leak, the engine will stumble.

I used to use ether but found that the effects of carburetor cleaner are more noticeable that using ether. Also check for exhaust leaks. They can also make a hissing sound.

Also check any moving parts to see if something is rubbing during movement of the engine.

Finally, you may have a 8' venomous snake living in your engine compartment so check before you stick your hand in there

Larry: I thought you'd only find them in Cobras or Vipers!


BWAAAAAAAAAAHAAAAAAAAAAA

Speaking of Cobra's

http://www.youtube.com/watch?v=Tpl1cKqFRrQ

Well guys; I checked everything and thought I hit the jackpot when I saw two of the four screws that hold the fan backing plate/alternator to the fan housing had loosened and were down by the lower engine tin. I put them back on and retightened and started the car and still had the same noise. I then retightened the manifold nuts (weren't really loose) and the spark plugs and nothing. Now, in fact, it has started to emit black smoke and go rough in the idle so, deja vu all over again. Now I know that what I suspected at first is the culprit. I wonder why these cardboard intake gaskets go bad so quickly. Since my heads are ported I'll have to take the existing gasket and use it as a template to modify a new cardboard gasket. Fun, fun, fun....

Ricardo, Try the dark gray gaskets. They feel like they have graphite on them.. Also, I've been very successful in just using silicone or Aviation form a gasket.

Ricardo:

Welcome to the club. Seems like I'm slapping in new intake to head gaskets about every Spring, and usually they go bad just before I head North. Happened this year, too. At Carlisle, I found a 1/4" drive, thin-wall, 11mm socket so I can FINALLY get at the two front (as the car faces) manifold nuts. Damn things are nearly impossible to get at.

I think the gaskets go bad simply because of the vibration inherent in the height of the manifold, plus you've got a 5 lb. carburetor sitting at the top, PLUS I believe the linkage causes some flex, too. Put it all together and it causes the gaskets to loosen and get sucked in.

Since I KNOW I'll be replacing the gaskets yearly, I always buy 4-5 sets and have them on hand, and when I install them I just use grease. That way they come out easily and leave little or no residue to clean up. Someday I may try the RTV route, but not yet.

gn

Thanks for the pointers guys! I have the light gray ones. I'd bought them some time ago for a rainy day (just did that with a new shortened clutch cable I just bought from VS to have as spare just in case). I'm fixing to remove the carb (thank God I have the 11 mm nuts) this afternoon and see if I can fashoin the new gasket using the old one as a template (my heads and manifolds are ported). By the way Gord, I had problems trying to get to the Speedstershop website last night.

Made and replaced the gasket yesterday and started it; still had the hissing sound. Somehow it went away after flogging it once or twice (the hillbilly tune-up procedure); wonder what it was; maybe some little debris in the right carb?

Check the neighborhood for missing pets or small children.....

Flogging it prob'ly chased away the snake that was in there in the first place!

Make sure Gordon didn't drop some latex glove bits down your carbureter! :-)

Got THAT right!

Gordon
One of the "Nine Fingered Speedstah Guys"

Bummer...I've been here since the 4th and I've driven around in the car for a while; it's been working flawlessly until this afternoon. Now it started doing the hissing on the left carb. It seems those intake gaskets don't last long. I remember doing that one close to a year ago and I haven't really driven the car that much. On my last visit last month I had to re-do the right one; now I guess it's the left one's turn...it really sucks.

This last time, when I changed them I got some Locktite HI-Tack RTV in an aerosol can (stole it from Chris) and shot a nice, even coat on both sides of the gasket. Actually, I think I did two or three light coats per side. Let then set up for 15 minutes after the last coat and put them on. We'll see how long they last.

I had been using just GP grease to get them moist, but they only lasted about a year or so at a time (sound familiar?) The good news was they were really easy to remove and left little or no residue. Not so with the Locktite, I'm sure, but maybe they'll last a bit longer.

I also used that nifty knuckle socket mentioned on the other site, and put locktite thread locker on the nuts (thanks, Leon!)

Now......we wait and see...

gn

Hmmm... I have 2 years and 10000 miles on the original intake manifold gaskets, with no problems. I've had my carbs off several times, and put them back on the original gaskets there as well - also with no problem. I wonder if CB Perf. uses some magical gasket material. Ricardo and Gordon, did you have your cars for several years before this started?

Definitely not a long time; I've had my car for four years and these carbs for the past 1 or 2. Funnily enough; the carbs in both our cars(Gord's and mine) are Dellorto 40's. I guess I'll use the compound as suggested by Gord; I'll see if I can fashion some washers to use with the nuts so as to prevent eating away at the aluminum manifolds while tightening. JJr told me there's a gasket remover in case you need to replace the gasket after using the compound. By the way I'll go by my local Kmart or Sears to get the Craftsman 11 mm socket Gord suggests.

Two years ago I had a leaking manifold gasket.
My mechanic at the time replaced the cardboard gaskets with copper ones.
Haven't had a problem since, knock on plastic...

I bought some manifold nuts, I think from Gene Berg, that have a flanged base and take a 3/8" wrench.

Some people may want to try those for a little more clearance.

I think you've emntioned the copper ones before, Terry, but how do you go about shaping them for ported intakes and manifolds?

Update: Re-did the left side using some spray-on copper gasket compound from Permatex on the new gasket and it still hisses; maybe it needs to be used and/or flogged or ran hard. I also found the left side fan housing bolt loose and laying on the engine compartment; that also led me to think it could also be the fan rubbing inside the housing but why the black smoke? The last thing I'll be doing is to re-tighten the spark plugs on that side so I'm waiting for the heads to cool off. Wish me luck...

Ricardo,
I have no idea. I wasn't there when the mechanic installed them.

Yeah, I tried re-shaping metal gaskets for elliptical ports once.

Absolutely a no-go, as the metal is shaped and crimped over an asbestos (or something) inner layer. When you try to re-shape the ID they simply fall apart.

I haven't seen any metal, elliptical or "D" ID versions (at least in any catalogs).

The easiest thing to do is just put on a round port version and "Git R Dun!"

The stock style metal and "asbestos" manifold gaskets are absolutely no good for our purposes. They will leak in very short order without any modifications. Why? They work well as a stock VW engine. If you think about loading and vibration of a dual carb manifold versus a stock manifold single carb it quickly becomes apparent they are two different beasts. When both VW and Porsche did dual carb engines they used 3 bolt systems and they used fiber gaskets, think of the 356 engines as well as type IV engines.... since we don't have the option of going to 3 bolt manifolds unless you do Comp Eliminator heads or the like, and they have 3 bolt manifolds anyhow, moving to a good fiber gasket is our only choice. I have had success with those sold by CB not that I really want to recommend anybody in particular.....

Another thing to think about is how tight should they be torqued down? VW and most of the aftermarket books do not have a recommended torque for the manifold bolts stock, much less how we use them. in my case I discovered I was not using nearly enough torque on mine and they would on ocassion vibrate loose. I got some grade 8 studs for my heads (manifold studs) and I used the recommended torque from a machinist manual for an 8mm grade 8 fastner. As I remember that was 15-18 ft pounds. Don't try that with the stock Chinese studs or you will be easy outing a broken stud most likely....but the point is valid I think. Fiber gaskets, with or with out RTV (your choice) well torqued down, will work well for a long time. Even with well ported heads, "D" or other wise

Haven't been able to solve the problem yet; I'm baffled since I've always solved it by switching the gasket; God knows. Ralph tells me it could be fouled plugs; I still don't get the hissing if the spark plugs don't work.

leak in the gasket at the TOP of the manifold (under the carb)??

Clogged idle jet making the throat hiss increase in volume? (try taking off the air cleaners (both) and see if it's much louder on the suspect side.)

Buena Suerte!

I definitely know it's on the left side and I'm suspecting clogged idle jets or at least something that deals with the idle circuit because the car runs perfect after 1,500 rpms. It's missing just a little bit so that if you let it idle it slows down little by little until you have to give it a little gas to keep it from quitting yet it does it very slowly. The hissing disappears after you shift to second gear and up. I'm actually using the car since it's not that bad. When I get back I'll try to clean up the jets using Cory's method with the wire from the sliced bread wrappers.

Ricardo, the Dell book sez NEVER use any wire to clean anything. If you suspect an idle circuit problem, try this. Wind in the mixture screw to see how many turns it is out from closed. Then unscrew it out, bearing in mind that there is a spring behind it that may fall out. Remove the spring as well. Pull the idle jet. Lay a rag over the jet hole and blow some carb spray then some air in the mixture hole. I used canned air with the little red straw. The straw bends so you can get the air right in there and swish it around. It'll blow out the idle circuit. Give the jet and it's holder a shot of air and put it back together and try it. This worked well for me without having to pull the carb and it only takes minutes. Worth a try.
The hissing has me scratching my head, though. When my idle circuit was clogged, the cylinder just quit firing at idle and backfired pretty good on deceleration.

~WB

Ricardo, I believe the difference is that Cory has Webers on his car.

If I remember correctly Herr Cory has larger Dells; am I mistaken? Thanks for the pointers guys. I have carb cleaner and will use it when I get back here in the next month or two (I'm flying back to NOLA on Sunday so I already put the car back on "hibernation" as we speak).

Gee, you mean I could be wrong? That's never happened before ;-)

I sure thought he had Webers, but you're probably correct. My bad.

Nope -- big ole' Dells. The only thing I use the bread-tie for is just to ream the idle jets. One wire, ideal for the purpose if done carefully. Everything else either gets a solvent and/or a toothbrush.

I'm going for a visit back to PR on Saturday and will be there for 8 days. Hopefully the problem will either: has fixed by itself (which can happen with these things after sitting for close to a month) or will need the all mighty Ralph to help me figure it out. Jjr was suggesting mounting bungs to the exhaust on both sides so as to dial in the mixture with an electronic reader but I think that is too much hassle; plus I'm of the school of "set it and forget it". I don't have to have the thing absolutely perfect as per a machine...I'm more old school: as long as it's not smoking and vibrating and it's synched and runs well; that's all I need. I posted this on the Samba and no one has been able to help; I figured someone else there had to have gone through a similar experience but....

Good luck and good hunting, Ricardo.

Thanks, bro....

Started the car and the problem is still there. Will see...

Fixed: my buddies at Volky Performance fixed it. After taking out the left carb and taking it apart and not finding anything wrong they decided to take the spark plugs on that side out. They noticed they were fouled so after cleaning them up on the glass bead machine they were re-installed and the problem was gone. I decided to buy a Pertronix conversion kit for my distributor to give it a better spark in case it starts acting up again. And to think I've been needlessly replacing intake manifold gaskets all along.....