Weber Carb Gasket & Nut Advice

[Jopacabra]

So I put a Weber 32/36 on pretty much when I first got the truck (RWD Z24, 1985 motorhome), and things were drastically improved from the trashed Hitachi. The thing shakes like a madman when it idles, so I've been playing with different things on and off trying to get it right (tuning, sparks, exhaust business, other vacuum leaks, etc.). Over time, I came to believe there was likely a vacuum leak at the base of the carb. Tested with starter fluid, blocking the line beneath, sure enough it's there. I tried tightening the nuts down a bit more, but it seems to only have made the problem worse. To add to it, it's dang near impossible to get a wrench or socket into those nuts, so I have no idea what the actual torque is like on them. I think I ended up overtightening the nuts on the passenger side and can't match that with the driver's side.

 

In the end, I've decided I want to just pull it off and try again. I was super intent on trying to torque the bolts down super evenly the first time, but maybe I can get it better on round two. So, I'm planning to order a new set of the Redline gaskets. Is there a better set, or a wiser way to make homebrew gaskets, or is that the right call?

Once I get things in, how has everyone else managed to get the thing torqued down? Any special tools or advice? I've considered finding a slender line-wrench adapter for my torque wrench and getting it right for sure, but I suspect that it may not work. I'm also considering trying to find some taller nuts for the studs, since that would solve one of the problems of the edge of a crescent or box wrench getting wedged between the nut and the 

 

I have heard since that it can be a huge boon to use Permatex Aviation on the gasket before installation, but not much in the way of confirmation. Can anyone speak to the wisdom of that? If it's smart, how / how much should I apply it? Both faces or one?

I've also heard that the bolts are want to rattle loose, so I'm planning to throw on some loctite blue this time.

 

Any other advice before I order all of this and get to it?

[captain720]

Yes loctite, aviation grade permatex make a gasket is a beautiful product and perfect for this application, but your window on it is small before it starts setting up not super beginner friendly. Gasgacinch is more new user friendly and does a similar task with less residue, I go gasgacinch on Weber adapter plates but I think the aviation grade permatex makes a better seal but it's not as easy to clean up later. As far as how much to apply it's a pretty thin product so just coat all the surfaces evenly in a thin layer

[captain720]

Make sure to not over torque and check your Weber adapters for flat with a straight edge

[datzenmike]

Over tightening leads to cracks, tightening more leads to a larger crack. Yes to the above some kind of thread locker to reduce loosening from vibration.

 

 

Vibration at idle can also be from...

A cylinder with low compression.

Check your valve lash.

Check both intake and exhaust plugs have spark then...

Check set ignition timing

[Thomas Perkins]

I wouldn't use lock tight.I've had my Weber since Fred Flinstone got a 4 door.I have no problems using a wrench.But any way,I use a Idle cut off solenoid on mine,it won't run with out it.Here's a video I did years ago.Mine has never came loose.But you do have to change the gaskets,I bought a rebuild kit for mine for 26 bucks on Ebay.Easy to do,Also clean it up.https://www.ebay.com/itm/191571346317,Here are some gaskets...https://www.ebay.com/itm/191587475677,I keep a extra kit on hand...I also have a pioneer throttle cable,better than the OEM ones....This card came with the idle cut off solenoid back then,now I have a Redline Weber that Iused the linkage and the idle cut off my the black choke one,both carbs work the same...I did sell the other carb on 720 World..Here's another site to get Weber parts that I use.. https://www.pegasusautoracing.com/keywordsearch.asp?KeywordStart=weber&KeywordButton=Go

 

 

[banzai510(hainz)]

3 minutes ago, Thomas Perkins said:

I use a Idle cut off solenoid

Not all Webers have this option unless he bought it with it already.

 

I dont use locktite and been fine for years

[captain720]

11 minutes ago, banzai510(hainz) said:

Not all Webers have this option unless he bought it with it already.

 

I dont use locktite and been fine for years

EMPI is currently selling idle cut solonoid on Amazon, I ordered one gonna test it out. Could be nice on 115° F days cause sometimes I get a little dieseling on those days

[Thomas Perkins]

You will need to get your dremel tool and grind away a little bit by the hole where it goes to make it fit or you will strip it out....My first Weber did come with it back then...my linkage is from the old Weber direct carb that is in the video...The Redline Webers don't sell the linkage that I use...Did you know that their is a filter in that big nut where the front lines fork off....Don't get your throttle nut to tight or it will stick...I have bought a Empi one and I believe the piece that goes on the end doens't come with it,I also bought a Weber idle cut off solenoid and it wouldn't work,but you can take the end piece off of it and put it on the EMPI one...I've had the Redline for a couple of years...Yes check out both solenoids and you will see the piece that is on the Weber and not on the EMPI,It might work with out it,but I never tried.

[banzai510(hainz)]

LIke I said before on the cut off selinoid the Weber 32/36 5A ia a manual  and can not have a selionoid install as it uses a different size jet holder.

Its best used for dieseling in the later year motors due to the open head designs.

 

A selionoid not installed is not going to cause a shaky at idle situation unless you dont have the mixture right. if one did have a idle shit off and the wire was off it would liley not idle at all cause not gas would be going thru the idle jet

Why buy a empi selinoid when one can buy a weber one

[Thomas Perkins]

I bought a Weber idle. cut off solenoid and it wouldn't work,still have it,Want to buy it,then I bought the EMPI one and put the jet on it and it has been working great.To check the Idle cut off solenoid,you start engine,then remove wire from it and it will die .I've never had a mixture problem with mine,make sure your timing is good..I tried mine without the solenoid and it would die...The Empi doesn't come with a jet,I have a extra brand new one...Also on the nut that holds the throttle their is a clip like washer that keeps the throttle from slipping,If it is not holding,it will cause idling problems.. tighting it to tight will cause the throttle to stick.I had to deal with it and bought extra clip-washers.Also don't have the Weber idled to high,will cause the throttle to stick...

[Jopacabra]

3 hours ago, datzenmike said:

Over tightening leads to cracks, tightening more leads to a larger crack. Yes to the above some kind of thread locker to reduce loosening from vibration.

 

 

Vibration at idle can also be from...

A cylinder with low compression.

Check your valve lash.

Check both intake and exhaust plugs have spark then...

Check set ignition timing

I was trying to consciously avoid overtightening to the point of cracking the adapter, but I guess we'll see when I get it off. I'm pretty sure I didn't go that hard.

 

Ignition timing was going to be my next step. Going to do that then the valve timing and replace the chain guide. I had a reasonably bad overheating event not long ago when a water pump went out while I was driving up some mountains. I had originally been getting like 18 mpg, then after that tanked to 13. Slowly been sinking now to 10-ish.

 

Maybe I should make a dedicated thread for that... It's kind of the root issue here.

 

 

3 hours ago, captain720 said:

Yes loctite, aviation grade permatex make a gasket is a beautiful product and perfect for this application, but your window on it is small before it starts setting up not super beginner friendly. Gasgacinch is more new user friendly and does a similar task with less residue, I go gasgacinch on Weber adapter plates but I think the aviation grade permatex makes a better seal but it's not as easy to clean up later. As far as how much to apply it's a pretty thin product so just coat all the surfaces evenly in a thin layer

How small is small? I was looking at the spec sheet and can't find a reasonable number on working time, but some comments say about 30 minutes. In my work (physics research) I've often worked with pretty demanding adhesives and solvents clean room style, so I suspect I wouldn't have much trouble.

[captain720]

I'd say you have 20 minutes with the aviation grade make a gasket and 30 with the gasgacinch. Depends on ambient air temp and humidity a lot

[Stinky]

How tall is your adapter?

 

There are some that are like 1/2" thick, and others that are, like, 1 1/2" tall.  The tall ones are Aluminum.  The short ones may be pot metal.  I always like the tall ones.  

 

Where was it leaking?    Adapter to Manifold or Adapter to carb.  Have you seen a cause?

 

As mentioned, use a straight edge and look for warpage.  

 

Silicone works wonders... and it does it on things besides breasts.

 

No to Lock-Tite....but I'd use Lock-Washers....although they aren't really needed.  But, I bet the Hitachi had them.

Edited October 19, 2021 by Stinky

[Jopacabra]

1 hour ago, Stinky said:

How tall is your adapter?

 

The 1/2". It looked cheap when I got it, but I didn't realize there was a better option.

 

Not sure whether the leak is carb to adapter or adapter to intake manifold. That's a fine line to test, really.

[Jopacabra]

18 hours ago, captain720 said:

I'd say you have 20 minutes with the aviation grade make a gasket and 30 with the gasgacinch. Depends on ambient air temp and humidity a lot

 

Missed this one... Thanks. I think that 20 minutes is plenty to slap down a couple gaskets and torque it in place.

 

I'll probably send some updates when I get things in and take it off.

[Jopacabra]

 

On 10/18/2021 at 1:15 PM, captain720 said:

Make sure to not over torque and check your Weber adapters for flat with a straight edge

 

@datzenmike

@captain720

 

So, the gaskets are in, and I'm getting the Permatex this afternoon. If I do find that the adapter is pretty unlevel, what's the best course of action as far as flattening it? I could take it to a friend with a belt sander, say, and wear it roughly flat. A few passes with finer grit should smooth the surface.

I've not done much metalworking, though. Anything I should watch out for? Would the belt sander likely affect the temper of the adapter or anything? Is there a better method?

[Stinky]

There is some guys on the net (tubers) milling a head w/emery cloth glued down to glass.

 

That will work.  If you use sealant, it doesn't have to be be real flat.

[datzenmike]

Works very well on thermostat housings and covers. Never use sealant, you'll never get it back off, too hard to clean up if you do and that's what the gasket is for!!!! 150 grit will do.

 

 

Reconditioned my cam followers with glass and fine wet emery cloth.

 

 

Even took the 'pucker' out of an L head. 150 to knock down fast and 220 to 'polish'.

 

[Jopacabra]

@datzenmike

2 hours ago, datzenmike said:

Never use sealant, you'll never get it back off, too hard to clean up if you do and that's what the gasket is for!!!! 150 grit will do.

 

Oh, really?! You do seem to be the "King Rat"... I see you in every single thread, and I'm inclined to weight your judgement a little heavier.

 

So, you're saying definitely don't use the Permatex. Just sand the surfaces (150 then 220) to get as flat as possible, then throw the gaskets on? If the sealant works, why not use it? It seems to me that the price of maybe needing to one day spend a couple hours getting Permatex off is worth the surety of "this will go on and you will almost definitely not have a vacuum leak here".

How tight is "tight enough" and how tight is "too tight"? I wish so badly I could get the torque wrench in there and take out the guesswork, but it seems that's not going to happen. Any advice on the best tool to get down there and best process to cinch it?

[datzenmike]

People today seen to have never learned that the whole point of a gasket is to seal between two surfaces. It will compress and deform to fit small defects. That, or they simply don't trust their own work and this maybe perpetrated by sealant makers themselves. Used to be 'engine shellac' and maybe one or two others but now there are literally hundreds of RTV and sealant products out there. In some cases a sealer is used in place of a gasket but not in addition to. Putting a sealer on a gasket is like using two condoms. You won't find too many places on a Datsun engine where sealer was used and then only tiny dabs of it in the corners. Simply put, it isn't needed.

 

If you want to use a sealer/RTV and a gasket go right ahead.

 

 

I pulled this RTV 'worm' out of the water passages of a KA head by an owner who sealed his water pump with an excess of sealer on the water pump gasket. What squishes out squishes in. Imaging the radiator and heater core. Imagine an oil pan gasket with RTV on it and how much squishes out and into the oil.

 

It's the most over used, over applied and nu-necessary product out there. 

 

Yes, it has it's uses. Some newer engines don't have some gaskets and a bead of sealer is used. Datsuns don't.

 

[Jopacabra]

24 minutes ago, datzenmike said:

Yes, it has it's uses. Some newer engines don't have some gaskets and a bead of sealer is used. Datsuns don't.

 

I appreciate the advice. With that, I think I'll go the old-fashioned way and ditch the sealant.

I appreciate everyone's advice. I'll report back with photos and results for posterity.

[DIY 1985]

My kit was Redline.  It could have been PO too, but I have an M8x1 stud, and on the other side is a finer pitch, M7, and it uses a 11mm nut instead of a 12mm (OEM ish) or 13mm (Hillman hardware).  Not using a 12mm wrench, but a 11 made all the difference, not easy, but doable with an unmodified/ungrinded Pittsburgh-brand stubby wrench set.  However, I don't know where to find this part.  Because I have only two of them, I'm inclined to think that it was part of the Redline kit?

 

Keep the telescoping magnet handy for this.

 

Ideally, for assembly, I'd use a socket head screw of proper length (at least five full threads exposed/engaged with adapter/manifold, plus a lockwasher and washer under that.  The ball-head Allen wrenches allow you to turn it at a range of angles, and a cut-off wheel can be used to fabricate a wrench dimensioned custom to the valve cover side of the carb.  However, I don't know if you could get such a screw thru the base of the carb because I've never done it.

 

Lock-washers.  Lock-washers maintain a degree of tension to keep threaded parts from coming apart without using excessive torque.  A smooth washer will prevent major galling.

 

In the Machinist Handbook, there are descriptions for classes of threads.  Sometimes thread engagement is really kinda tight, as specified by engineer.  IIAC, taps come with classification of fit, if you look hard enough at the specs.  However, I recall a pair of fasteners in the Weber sandwich had tons of play, so I used teflon tape to create a tighter fit, more resistance for the stud or screw to turn, and greatly reducing the amount of wiggle.  Standard fix for this is Helicoil or thread insert, but with original Datsun parts, I prefer to minimize modification.  I'm not a fan of using gobs of sealant in a tube, but, some folks use it standard in coolant related fasteners with great success at resisting seizure due to corrosion.  Four, fresh/new, lock-washers would be standard spec for keeping any carb on a plate, manifold, as it keeps tension in the fasteners.

 

In engine building, they stress the importance of clean threads for proper torque values during assembly.  Not that I'm suggesting using taps and dies in this situation, but, simply cleaning the threads will help.  For the female threads, usually running a male thread soaked in gasoline will loosen up dirt, for male threads, a steel wire toothbrush.

[Stoffregen Motorsports]

Having been through this process many many times, the best results come from using good gaskets on sanded flat adapter plates and fastened together with red loctite on the short threads. For the studs, red loctite on the adapter end with flat and lock washers on the carb end. A specially bent open end wrench will allow you to get to all the nuts easily and an approximation of the 25# of torque can easily be felt by experienced hands with no torque wrench needed.

 

Note - the 25# of torque is standard for an 8x1.25 high quality bolt or stud, but you are more likely to strip threads in aluminum when using a bolt vs a stud. As an example, whenever possible, I convert intake and exhaust manifold hardware from bolts to studs to ensure no aluminum is stripped from the threaded holes in the head.

[Jopacabra]

So, I got everything sorted with the vacuum leak. Turns out in the end that I didn't remove the "other plate thing" as mentioned in the guide I followed here like 6 months ago:

 

 

Here's the thin, odd plate that I assume is some sort of fuel air mixing plate:

 

 

 

I also noted that one of the studs installed into the intake manifold was loose enough to be removed by hand, so I removed them both and double-nutted them down harder this time with some blue loctite, which was just what I had on hand (I don't tend to use red enough to stock it, and I didn't want to end up railed if I ever needed to remove them by hand).

 

So, I checked the adapter plate with a straight edge. I'm not sure exactly what others have meant by "not flat", but there was definitely surface variation up to about 1mm. I took an orbital sander at 120 grit to it on both sides to slim the variance down to about 0.25mm. I tried to get some photos, but gave up because it was too sunny and obnoxious. I was planning to go over it with 220 grit, but I discovered after all of this that I had used my last bit of papers finer than 120 for something else. I was out of time, so I cleaned up with rubbing alcohol, threw in the adapter studs and allen screws with more blue loctite and slapped it together with a fresh set of the gaskets from redline.

 

Tightening down the bolts, I ended up having greater success with a 12 point box wrench for the away side (passenger) and just a crescent wrench at an angle like the first time for the valve cover side (driver). I aimed for about 25 ftlbs torque by feel, and it worked out okay. I think the main issue the first time around was I got sloppy and rounded two top corners of the nut on the valve cover side when I slipped reaching over the engine. I also forgot to buy new nuts, so I just flipped the rounded nut and it worked fine. I went with the supplied wave lock washers and the blue loctite.

 

The engine now runs better than ever before by a large margin. No more violent shaking and freaking out, no more idle troubles, no more evidence of a vacuum leak when searching with starter fluid.

 

BUT... There's suddenly a new buzzing coming from this mystery device under my passenger side dash. I believe it's the electric choke relay, because it is significantly louder when the electric choke is connected than when it's not (engine hot or cold). Other threads suggest it could also be the fuel pump relay.  I checked the alternator, and it's outputting 14.25V according to a good meter. Not sure what that business is about. Anyone have any ideas? When reinstalling the carb, I tapped it a bit with a rubber mallet, and I think I clipped the edge of the butterfly valve linkage (under the air filter). It didn't seem to be damaged or have any ill effects, ust flicked open and closed, so I thought nothing of it at the time. I still don't think it has anything to do with this, as I was quite gentle, but it's here for posterity.

Now that I'm sitting here at my desk, I'm thinking maybe I disturbed the grounding wire when I was shuffling around in there. I'll give that a look when I get back. In the meantime, here's a shot of the way I have the electric choke connected. It's the same as when I initially installed the carb, and I didn't have any problems with the relay before.

 

 

Anyway, thanks for all the advice in the thread. I'll start troubleshooting the buzzing later. For now, mileage, power, and smoothness are all way up, so I'm quite happy, if a bit irked by that incessant buzz.

[Stoffregen Motorsports]

Common misconception with red loctite is that it makes fasteners impossible to remove. The only fasteners I've had problems removing held in with red loctite were crank damper bolts (on race engines), 1/4" set screws used in aftermarket steering u-joints and AN fittings in dry sump oil pans.

 

Glad you got it working.

 

Yes, that plate thing is weird, and stupid and clearly an afterthought. Way to go Nissan.

 

A bad ground could cause the relay to buzz, as it is searching for ground.