1.4 weber carb mounting studs sizes?

Post by **340LE** » 23 Jan 2008 08:14 pm

Got home today and thought i'd check the airfilter mounts as i gave it a wiggle a few weeks back and it moved. Anyway, opened it up and two of the three studs came out by hand complete with thread.

My access to parts, screws and bolts is pretty rubbish and i managed to come up with something that should get me to work and back tomorrow if i take it easy.
What i did not realise is that, certainly for the rear most mounting stud, it is possible to access the underside of the carb, i.e. where the other end of the stud pokes through if you tighten it up too much.
So, seeing that i now have no thread in two of my three fixing mounts, i'm after a slightly longer threaded stud with a nyloc on both ends.

The question is, what size, thread and length do i need to ask for and where do i go to get them?

Post by **2 Fast 4 U** » 23 Jan 2008 10:25 pm

The normal size is of the studs is M5, but I drilled the holes up to 5 mm and taped M6 thread, I also drilled the holes in the air filter housing up to 6.5 mm, now I have 3 metric screws M6 x 25 mm that I screw in the carb top instead of the three studs comming up from the carb, works very good.
If you can't get M6 you could use ¼" instead.
good luck!!!!

Post by **Ian Hutchinson** » 23 Jan 2008 11:11 pm

Is this a common problem?

My air filter housing is currently held on with one bolt - the other two are missing. It feels pretty solid though and doesn't flop around.

Post by **Chris_C** » 24 Jan 2008 12:59 am

Ian, one bolt really isn't something I'd recommend, theres a lot of leverage on the pie shaped airbox!

Something mac told us a while ago if you do use a piece of rod, remember that threaded rod with abrade the inside of the hole on the carb, best to use a piece of smooth rod that you tap just enough each end!

Post by **Ian Hutchinson** » 24 Jan 2008 02:43 pm

Chris_C wrote:Ian, one bolt really isn't something I'd recommend, theres a lot of leverage on the pie shaped airbox!

Something mac told us a while ago if you do use a piece of rod, remember that threaded rod with abrade the inside of the hole on the carb, best to use a piece of smooth rod that you tap just enough each end!

Thanks Chris
This is now added to my growing list of things to do!

Post by **340LE** » 24 Jan 2008 11:02 pm

2fast, thanks for your quick reply. Gave me something to think about. Certainly sounds easy to remove your airfilter now, but it sounded like quite a bit of work to drill and tap.

Ian, there is loads of information about this in this forum including a sticky at the top of the engine (1.4, 1.7 2.0 and diesel) section. I'd been driving around for ages with just one holding the airfilter on and hadn't realised how rough it was. Do you do short journeys with either throttle open or closed (coasting) and very little in between (cruising at half throttle)? I found that motorway cruising it tended to kangeroo very slightly as if it was missing, like a dodgy HT lead. The air leaking in to the carb causes all kinds of problems, rough idling and shuddering when you turn it off were two i noticed. From what i understand 1.4s (usually) shake the airfilers off and 1.7s (not sure, don't have one) shake the manifold off.

Chris, agree about the bolt. I'm assuming you mean the threaded section would damage the hole in the carb? I wouldn't have thought so and seeing as i've got no thread left to damage it doesn't really matter does it? I've just used longer threaded bolts.

Had a proper go at it this evening. Required a few bits n pieces to get to where i am now. Got some pictures and i'll try to get them online with a write up as soon as i can.

Thanks.

Post by **Ian Hutchinson** » 24 Jan 2008 11:30 pm

340LE wrote: Ian, there is loads of information about this in this forum including a sticky at the top of the engine (1.4, 1.7 2.0 and diesel) section. I'd been driving around for ages with just one holding the airfilter on and hadn't realised how rough it was. Do you do short journeys with either throttle open or closed (coasting) and very little in between (cruising at half throttle)? I found that motorway cruising it tended to kangeroo very slightly as if it was missing, like a dodgy HT lead. The air leaking in to the carb causes all kinds of problems, rough idling and shuddering when you turn it off were two i noticed. From what i understand 1.4s (usually) shake the airfilers off and 1.7s (not sure, don't have one) shake the manifold off.

Hmm...interesting. Ive posted on my running problems in that thread. I think at first problem running (including a couple of break downs needing AA assistance) were the result of a number of problems all occurring at the same time. The car had been sadly neglected.

Now that the HT leads, dizzy, rota arm etc have been changed, the carb bolts tightened up and the fuel tank breather cleared things have improved to the point where it feel as though I can complete a trip without a breakdown. Ive covered about 300 miles this week commuting with no major problems. The engine is hesitant at times though - as though its slightly missing - this is usually when cruising and the revs are fairly constant. Its smooth under steady or hard acceleration.

Despite the fact that the filter housing seems tight (held on with one bolt) I wonder whether when the engine is going there is enough vibration to allow air to leak past the base of the mounting? I guess that I will know when Ive added a couple of M5 bolts and tightened the whole thing down!

Post by **Chris_C** » 25 Jan 2008 01:26 am

340LE wrote:Chris, agree about the bolt. I'm assuming you mean the threaded section would damage the hole in the carb? I wouldn't have thought so and seeing as i've got no thread left to damage it doesn't really matter does it? I've just used longer threaded bolts.

I think Mac was meaning that the thread would act to abrade the inside of that hole in the carb, enlarging it which eventually would get to the point of shaking the nut and bolt loose, putting you back to the original situation. The problem being the carb top is ali and the bolt steel. As to how long it would take or how much of a difference, I wouldn't know!

Post by **mac** » 27 Jan 2008 06:07 pm

Actually what I meant was that if you use threaded rod it could abrade the hole in the plastic air cleaner housing. The size and weight of the aircleaner allows it to move on the carb top even when tight! It is more prone to do this if the gasket between the filter box and carb is missing or has been replaced by a paper gasket (should be rubber). Any movement of plastic against steel thread will soon give a much larger hole!!

I still favour a proper solution (stepped stud locktited into rethreaded carb top using correct size nylock nuts to retain the housing). But then I'm an old fart.

Mac.

Post by **Chris_C** » 27 Jan 2008 06:21 pm

See... I just remember half of the answer

Cheers Mac!

Post by **340LE** » 29 Jan 2008 09:22 pm

Ian Hutchinson wrote:The engine is hesitant at times though - as though its slightly missing - this is usually when cruising and the revs are fairly constant. Its smooth under steady or hard acceleration.

That's exactly the same problem i have! The only things i haven't changed are the dizzy cap and rotor arm and the oil as of yet. Wonder if these will make any difference as i didn't think they'd deteriorate that much being electronic?

I've changed the fuel filter, air filter element, ht leads and plugs.

I threw away the greaseproof paper gasket and replaced it with gasket maker.

Post by **340LE** » 29 Jan 2008 09:29 pm

My oil's not electronic, obviously.

Post by **Chris_C** » 30 Jan 2008 10:34 am

Dizzy cap and rotor arm make a huge difference, they are a 12monthly service item!

Oil is a 6 monthly service item, so should be done pronto too