The Triumph Dolomite Club - Discussion Forum

Hi Guys,
My car is now developing a reputation for itself in our family for being unreliable. Been fine for the last few years but recently....
Basically the car won't fire once it's warm.
The issue must be directly related to me fitting an airbox.
The engine is running on twin dellortos. They have been running with just open trumpets. Just fine.
For once, trying to be cautious, I thought I had better add an air filter.
I first fitted the base plate for the air box. The warm idle rose from 800rpm to approx 1100rpm, also it started to become very difficult to re start the car once it was warm (hence the bad rep, sat at a petrol station for example )
So, I adjusted the idle screw to bring it back down.
It still doesn't like starting warm.
I have fitted the whole air box now, with cold air feed into airbox. It is still pretty much impossible to re start once warm.
From what I can tell, it must be a fuelling problem.
Any ideas what to do? At the moment I feel like I have spent a lot of time and money on the filter and box to ultimately make the car worse. That's what being sensible gets you

Trying to think back to when I had delloroto's on a car, but my memory is failing me...

What I don't get is why just the baseplate made any difference at all? It will do nothing.....except join the 2 carbs together. Thta is my only feeling, it has caused an issue with the carb to manifold sealing. Thackery washers?

Seems it may be running too rich, and when enclosed in a filter setup which can reduce air in to the carbs. How close are the back of the trumpets to the filter element? The air has to turn 90 deg and maybe theres not enough room to get good flow there.

Tony

tony g wrote:Seems it may be running too rich, and when enclosed in a filter setup which can reduce air in to the carbs. How close are the back of the trumpets to the filter element? The air has to turn 90 deg and maybe theres not enough room to get good flow there.

Tony

Hi,

The filte is at the inlet to the airbox, rather than attached to the carbs themselves.
Still, this was happening before the full airbox was on, even with just the base plate.

There is another hole above the left trumpet on each carb, don't know what it does but it should not be blocked, has your backplate blanked this off?
http://s1295.photobucket.com/user/Tony0 ... 8.jpg.html

Tony Burd wrote:There is another hole above the left trumpet on each carb, don't know what it does but it should not be blocked, has your backplate blanked this off?
http://s1295.photobucket.com/user/Tony0 ... 8.jpg.html

That hole sits right on the curve between the rear face of the back plate, and where it starts to curve to the top side (the base plate is a deep base plate, i.e. It is approx 60mm in depth, before connecting to the other side of the air box).
I have had to cut a hole in the base plate for that hole to allow air to circulate. I had hoped this would be sufficient but it is starting to feel that it is maybe the culprit...

I'll take some pics tonight which may help illustrate.

Of course, you can firmly diagnose the fault being the back plate you've added...by removing it again to see if the problem goes away. Co-incidences do occur, and when they do its easy to blame something unrelated to the actual cause of the problem...

Once, not wanting to start when warm was a problem I put down to fuelling and I wasted a lot of time and effort looking for what eventually transpired to be a starter motor fault on the fuel side of the engine!

xvivalve wrote:Of course, you can firmly diagnose the fault being the back plate you've added...by removing it again to see if the problem goes away. Co-incidences do occur, and when they do its easy to blame something unrelated to the actual cause of the problem...

Once, not wanting to start when warm was a problem I put down to fuelling and I wasted a lot of time and effort looking for what eventually transpired to be a starter motor fault on the fuel side of the engine!

Hi Alun, yes indeed. I will try that one. The base plate came off to isolate idle change earlier which it did. Too much of a coincidence I think.....

Thanks

I'd go with Alun's take,
Hot starting issue sounds like it could be ballast bypass related to me.
Do you still have a ballasted ignition?

Jonners

Jon Tilson wrote:I'd go with Alun's take,
Hot starting issue sounds like it could be ballast bypass related to me.
Do you still have a ballasted ignition?

Jonners

I still think that would be some coincidence!
The car has been running non ballast for the last 4 years and with no starting issues.

I am going to run a test. Replicate the hot start problem and then force cold air down the carb vent that could be the culprit to see if it makes a difference....

I had a hot start issue with the MGA which turned out to be the two year old coil failing!

Ok good to eliminate the ballast then...

Looks like you have blocked a hole then somehow.

Jonners

do you have any pictures to make it a bit clearer, some time a picture tells a thousand words

Here we go, here are some pics that I took last week (delayed upload due to photobucket problems, so apologies for that) -





Here is the complete set up. Deep backplate, customised carbon box with cold air feed leading to snorkel pointed to the front of the grille.



Thanks all for your input.

I had a hot start problem with a 90's Peugeot last year.Exceptionally annoying as I tried changing bits.

Turned out to be a faulty starter motor.Looks like the windings were shorting out when it got hot and drew too much current.Ran like a dream after.So,check the ignition coil and stater motor for that issue.