Air filter -> Carb gaskets

[rolallan]

OK, I accept this may be a stupid question, but I feel I should ask.  Whilst tinkering with the car last night, I had the air box off.  when I came to refit it, I noticed the gasket seemed to be missing a hole, my air box, air filters and carbs have three holes on one side of the larger hole and two on the other,  one each of these being for the bolt, the gasket only has two holes (1st photo).  I checked my stash of gaskets and they were all the same.  I checked my parts manual and it believes the gasket should have three holes, like the second photo.

i did some research and it appears the same part number, 148006, appears to have two configurations as a two hole or three hole version depending which Triumph specialist you go to, so somewhere I've picked up the wrong one and not realised.  

So, given I have one hole on each carb covered, does this matter?  I assume the answer is yes, is there a laymans reason why as I have only begun to scratch the surface on understanding carburettors.

As an aside I have ordered some alternate gaskets from another well known Midlands dealer so I'm intrigued to see if they are different.

[Pete Lewis]

always look out for an old pushrod, the spherical end is ideal to press against the gasket over the hole and a tap with a hammer will punch you a nice round hole.

only one hole  on  your older stromberg   CD/CDS is used for the float bowl  venting, there are two hole so you never get it wrong way round

the 4 hole version uses one  extra hole for the temperature compensator throttle air bleed  you can use the 4 hole on any but the two hole cant be used on CDSE with the side mounted compensators. ...unless you make a few holes.

Pete

[rolallan]

Thanks Pete, I might just punch the hole to see if it makes any difference to the stuttering under acceleration, although my Strombergs are CD 150 units, so from what you are saying it suggests not, it may still be mixture.  I think it could be time for a colourtune.

[Pete Lewis]

make sure the jets are centralised, set the float height to 18mm ( strangely the stromberg manual states 16mm in some specs.  )  must sus that out.

make sure the filters and all the gaskets dont cover any of the ports
use engine oil in the dampers
check the diaphragm for perforations
if its swollen wash it in petrol.to resize it.
make sure no debris is lodged behind the float needle bodies.or floating in the supply pies.

never use plugs with an R in the suffix  ( as supplied by some )

check the dizzy splindle has no side float wear. as this changes the point gap when running

use 97+ ron fuel with optimum timing.

and you should be OK

Pete

[rolallan]

Ok,  I've put relevant holes in the gasket and it's made no difference, so not that then.  

I have some spare diaphragms, so I shall replace them next although the current ones look fine but are about 3 years old.  I'm trying not to make too many changes at once to try and understand where the fault might be.

Essentially I can cruise happily at 50 or 60 in 4th and overdrive, put my foot down and she'll stutter a bit so I ease off the acceleration and she's fine again.  Gentle acceleration doesn't cause a problem it's the heavy acceleration that causes the stutter.  Same problem occurs in other gears as well on heavy footedness, but not on steady acceleration.

I always use engine oil in the dampers and they are fully topped up and don;t lose too much over time.
Timing is 14 BTDC but I will try and set it back to 13 BTDC and I use Shell Nitro V+ whenever possible or it's equivalent.  


I have some time tomorrow so will try and do little things and test.

[rolallan]

I spent some time at the weekend reading about and watching any video I could find to do with carbs.  As a result, I replaced the diaphragms and set the idle back to basics then went through a simple balancing process with two feet of garden house.  As a result my car now idles nicely and accelerates when I expect her to.  The hesitation has gone and I feel like she's responding to the throttle again. I still think a colortune is in order, but she's a lot happier now and ready for the sun and I've learned a great deal about carburettors.

Thanks for the advice, always appreciated.