Webber Airbox Clearance

[l10tus]

Just fitted the Webbers as the rebuild continues, to find there is very little clearance between the bottom of the air box metal backing plate body and the fibreglass of the Drivers footwell ?

At best, the gap is about 6mm / 3/8" ?

Is this going to foul when the engine starts, whilst engaging reverse, etc ?

Having had a similar problem on the exhaust side, did change the exhaust side engine mount for a heaven duty one, which cured the problem on that side (with the heater valve clearance to passengers footwell,) after finding the standard LHS engine mount had just collapsed even though the engine had never been run !

Although the carb side one appears to look ok ( not collapsed and with clearance between the centre mount and the top metal safety hoop) what clearance should I be looking for?

( methinks I should have changed this for a heavy duty one too ?)

I checked the forum for answers, but couldn't actually find a specific "clearance dimension" listed as a true guide.

Your clearance / tolerance dimensions would be appreciated, between the lowest part of the carbs or air box and the fibreglass footwell ??

Regards,

Phil.

[alan]

on the carb side it is a different part number. It is higher than the exhaust side to stop airbox touching top of footwell

[billwill]

The right-side engine mount is supposed to be higher to give a bit of clearance there, but how much? Dunno. Too high and the carbs hits the bonnet instead.


For years mine was annoying me as the airbox hit the fibre glass when the engine vibrated and it was cutting a notch in the fibreglass, I tried padding with bits of old neoprene wetsuit and later an aluminium plate.


Then a year or so ago I had had enough.... I cut away the area under the airbox and shaped an aluminium plate over the pedals as far down as possible Held in with self tappers to the rear of the airbox and in through the front wall near the brake & clutch cylinders. Then I glassed in over the plate and ended up with an area under the airbox about a quarter inch lower than it used to be.

The ali plate had many right-angled lips etc for fastening it, so the only way to get the shape was by making a template with cardboard from a large packet of cereal.

[rgh0]

With the correct high lift engine mount for the RH side you should be able to fit you fingers under the air box and the air box will not hit the foot well with engine movement.

cheers
Rohan

[l10tus]

Gents,

Thanks for the speedy replies.

Rohan, it Looks like I've got the same problem on the RHS, as I did on the LHS. ,!

I just ordered another Heavy Duty mount ( should have purchased the pair!).

I also popped into my local Lotus Classic showroom to buy a few other bits and inspected the Elan's on show there - several were suffering with the same issue.

I couldn't get even my little finger under the air box on the ones I checked !

One had received the "cut away solution", suggested above.

The Parts Manager suggested that this was a common problem with the Elan, whereby several suffered the "dreaded rattle" under high torque conditions, like when you start up, go to pull away, engage reverse, etc.

Not wanting to put up with this sort of situation, I shall try the new H/D mount and report back.

I just hope this doesn't push the problem up even higher ( bonnet rattle !)

Thanks for the guide clearance size ( approx 1/2" or 13mm)?

Regards,

Phil.

[Lyn7]

Hi Guys, here is a different slant on things as sometimes the obvious is not the answer. Many years ago when I purchased my sprint I had this problem of the carbs hitting the pedal box frequently. Lots of new engine mountings later and trying to find a solution I had failed! I even butchered the air box and only succeded in a part improvement. Having learned to live with it I then decided to change the sub frame/chassis. When it came to replacing the body all the spacers I had saved from the original chassis were not needed with the replacement.
As soon as I installed the engine and carbs I quickly realised my problems were over as the pedal box had now gone down in relation to the chassis and therefore the carbs
So to date, I have just checked, and a 1/2" inch drill bit will not pass under my (new) airbox but a 7/16" will. There is certainly no chance of the airbox hitting the pedal box with this measurement. I think 3/8" would probably be ok.
Regards all, Lyn...

[twincamman]

I just spent the morning switching sides on my motor mounts . ( Growel snarl grumble )They were even that is to say the motor sits flat when a level is placed on the cam cover , and it made no change...... soooooo 50 years from now the car will still have a motor that is level when checked by the new owner ......Ed

[alan]

hi Phil,
imho with respect, i suggest your local Lotus showroom parts manager does not know Lotus very well.
The higher mount should be fitted for cars with Weber or Dellorto carbs on Elans.
It seems strange to put a car up for sale with this problem that is very easy and cheap to fix

[englishmaninwales]

I was driven mad by this problem on my previous Elan. My current Elan has been, I suspect, fitted with the correct engine mount as I can just squeeze my fingers between the rear of the airbox and the footwell.
The engine is higher on that side, but doesn't foul the bonnet.

[l10tus]

Alan, Lyn, Englishman, in fact All,

Thanks for the replies.

The measurements and findings have really helped in making decisions.

FWIW, I personally couldn't possibly think of cutting fibreglass parts away in order to resolve this issue, the original design would not have required any of that treatment would it?

Although I haven't fitted the Airbox yet, I dId notice I had to lift the engine considerably with the trolley jack whilst replacing the bolts back into the new mount, so I'm hoping the problem has gone away ?

Guess what, I checked the 'old mount' and found it to be the same as the exhaust side one and had failed again !

As stated previously, both engine mounts were brand new 6 years ago, have never had to provide support for a running engine - and have both failed - whilst the car has been standing still in the garage! (Were these due to a 'bad batch' ?)

I hope I get better value out of the latest replacements!

Again, upon checking, I found that the metal parts had all been black painted prior to vulcanising - so the rubber had been 'attached' to the black painted metal parts - I would have thought that painting the metal to which rubber was going to be vulcanised to was not ideal, and would definitely result in a less than perfect joint ?? - ( any vulcanisers out there ?)

So, now on to the next issue - static timing with an Aldon igniter fitted ???? - (then I can refit the carbs and Airbox to check clearances...........).

I just realised that this is why the car was probably laid up some 36 years ago - as when I acquired it, the LHS engine mount chassis bracket had parted company with the chassis - ( probably caused by a failed engine mount?) I was just thinking, who would drive the vehicle round in that state ???

Upon reflection - I'm glad they did!

Thanks for all who assisted - perhaps this woeful tail will nudge others into checking the state of their engine mounts and help resolve those dreadful thumping noises they have at high torque times!

Regards,

Phil.

[Mazzini]

I had this problem in my S3; under high torque situations, setting off on a slope (C/R box with high first and 3.5 diff), the carbs would rattle against the pedal box bulkhead. I got a new mount from the guy on eBay whom advertises uprated mounts and half an hour later with ramp and a transmission jack the job was done and the problem has gone

There was perhaps 1/4 of an inch difference between the two mounts, which I guess is down to the rubber settling over time.

[billwill]

I guess my current engine mounts are getting 'tired' as I now have the problem on the other side; an exhaust pipe, tapping the chassis when idling.

Makes the Elan sound like an "any old iron" cart when idling at the traffic lights.

Have you got the name or a link to the guy on ebay with the uprated mounts? TIA.

[l10tus]

Bill,
Obtained mine from QED.

Great service, delivered the next day!

Regards,

Phil.

[Plus 2]

As stated previously, both engine mounts were brand new 6 years ago, have never had to provide support for a running engine - and have both failed - whilst the car has been standing still in the garage! (Were these due to a 'bad batch' ?)

I hope I get better value out of the latest replacements!

Again, upon checking, I found that the metal parts had all been black painted prior to vulcanising - so the rubber had been 'attached' to the black painted metal parts - I would have thought that painting the metal to which rubber was going to be vulcanised to was not ideal, and would definitely result in a less than perfect joint ?? - ( any vulcanisers out there ?)

Phil.

Phil,

The elastomers (rubber bit) can actually be bonded to many different surfaces. What is absolutely essential though is using the correct bonding agent depending on the surface properties to be j/bonded together. http://www.sternmfg.com/rubber-to-metal-bonding.html

Modern glazing of glass windows/screens are utilising similar principals and typically there was two different primers/bonding agents that had to be used where glass was one surface and the painted body the other.

Thankfully the label on the bottle for the glass was green and the body label was red albeit the bottles exactly the same. It lead to a simple saying though for us that was 'Green to Screen' so we never got the wrong bonding agent mixed.

My concern though in reading these comments in this thread is that generally we are seeing many rubber parts coming from the Eastern countries and it is now one of the biggest topical discussions on several classic car forums regarding the quality and longevity.

The manufacturing processes are not fully understood and the chemical recipes for the rubber compounds situation as in 'fit for purpose' just even less. They are just excellent at making visual copies.

I have recently had a new top hose where the coolant actually leaked through the inner rubber wall and coolant was coming out the end between the two inner and outer where the reinforce material was sandwiched. Then after fitting on one of my cars a new quarterlight rubber two weeks later it had all cracked. Obviously no understanding of UV stabilisation for exterior rubbers.

These parts were all purchased from main vendor suppliers..........which makes it even more of a concern.

Lets hope your issue is just isolated

Regards

Steve

[Chancer]

both my parents worked for the factory that produced these and other rubber to metal suspension bushes in the 60's and 70's, they are no longer with us but as a car mad youngster I do remember and awfull lot about the process and surface treatments etc as I was always having stuff stripped or plated for my bicycles.

Firts of all the bonding process is not vulcanising, that is what turns natural rubber sap into a useable, mouldable and bondable product and involves principally the addition of sulphur IIRC.

Rubber to metal bonded bushes are made on high pressure rubber moulding presses at elevated temp?ratures, the pressure and temperature are critical but the most important thing was the surface finish of the metal parts, they were never painted but shotblasted, electro-plated plated (usually cadmium) and degreased in a tricloroethylene vapour bath.

I remember buying a "new" 2000E gearbox mount in the 90's and being completely unimpressed with it, it was made from scraps of metal cut out hy hand and with a block of rubber glued between them, it was not a bonded bush and lasted all of one afternoon in service.

I suspect that all the modern reproduction parts are of a similar ilk as the machinery and control of manufacture to produce correct and robust rubber to metal bonded parts is very expensive and the old equipment was very labour intensive, unless you are a supplier to the mainstream manufacturers turning out millions a day on robotic Equipment its going to be an Indian sat on the floor using his feet as a vice to glue together scraps of metal and bits of rubber, that is not meant to deman those doing this work rather those that exploit them and us the buyers.

I know for sure that the current offerings of Metalistik drive shaft donuts are not in anyway shape or form comparable to the originals that were in themselves only just up to the job in an Elan and more at home in a Hillman Pimp.