Project Dollywobbler's Invacar - Ongoing

[dollywobbler]

Had another run out this morning. Well, it was such a lovely day I just had to.

 

That's TWC having a well deserved rest after hitting the dizzy heights of 60mph! The good news is that the oil seems to be mostly staying inside the engine now, and the oil pressure light is mostly behaving. There was one point when it flashed on at idle, but then it went away again. Odd. That was before our speed record attempt.

 

The bad news is that the magic potion I added to the fuel has done absolutely piss all. I'm still getting massive bogging under throttle application at times, which clears if I either pull in, select neutral and give the engine a few revs, or if she goes 'Tuk!' and then she pulls cleanly again. So, I think it's approaching time to park her up for a bit and properly investigate. I also need to look at the master cylinder, as doing 60mph in an 'unsafe' trike with iffy brakes is pretty stupid.

[purplebargeken]

Fab little thing.

[jbz2079]

Could the carburettor problem be as simple as water in the float bowl?

Classic symptom is the "TUK" spit back as it goes weak the pressure in the inlet blows the water back from the main jet and off it goes, till next time.

[dollywobbler]

Could the carburettor problem be as simple as water in the float bowl?

Classic symptom is the "TUK" spit back as it goes weak the pressure in the inlet blows the water back from the main jet and off it goes, till next time.

 

Pretty sure not. I've emptied the float bowl several times, and the fuel tank was absolutely dry before I put fresh fuel in. Probably won't get time to tinker for a week or two.

 

Also, there's still a sodding oil leak. I think it might be from one of the tubes that goes from rocker cover to the block.

[mat_the_cat]

 

 

I love this picture - the promise of spring around the corner, and a summer of Invacar motoring ahead of you

[dollywobbler]

Aye. Once I pull the sodding carb off and find out what's wrong with the sodding thing. And cure the oil leak that hasn't gone away. And stop the brakes pissing fluid everywhere. And fit some sound deadening...

 

It's been relegated to the back of the garage again now...

[DodgeRover]

Have you checked the valve clearances?

[Squire_Dawson]

What carb does it use, could it require some damping like the SU. Or else if it has a diaphragm could it be split and there be an air leak somewhere causing it to weaken and cut out under load.

[dollywobbler]

Have you checked the valve clearances?

 

Yes. Spot on.

[dollywobbler]

What carb does it use, could it require some damping like the SU. Or else if it has a diaphragm could it be split and there be an air leak somewhere causing it to weaken and cut out under load.

 

Single choke Solex 40 PID I think. I have no idea how it works really.

[The Reverend Bluejeans]

hitting the dizzy heights of 60mph!

 

Jesus, I had a moment of cold sweat just imagining that. 

[LightBulbFun]

 

That's TWC having a well deserved rest after hitting the dizzy heights of 60mph!

 

 

I think the saying everyone is looking for is: Brass balls 

 

so how did it handle at 60Mph then?

[dollywobbler]

It was fine actually, but you have to be ridiculously precise with steering inputs. Lock to lock involves about six inches of travel, so it is terrifyingly direct.

[adw1977]

It was fine actually, but you have to be ridiculously precise with steering inputs. Lock to lock involves about six inches of travel, so it is terrifyingly direct.

Sneezing at 60mph not recommended, then?

[dollywobbler]

Sneezing at 60mph not recommended, then?

 

Frankly, sneezing at 20mph is pretty risky.

[red5]

Great stuff - my late grandads friend/work colleague had one. Fascinated me  - I got to have a go as a 'passenger' round a Midland Red workshop. Exhilaration and terror in equal measures.

 

Re: the random carburation - does it play up if you slowly apply throttle, or just on initial 0 - 50+% opening?

 

Sam

[dollywobbler]

Great stuff - my late grandads friend/work colleague had one. Fascinated me  - I got to have a go as a 'passenger' round a Midland Red workshop. Exhilaration and terror in equal measures.

 

Re: the random carburation - does it play up if you slowly apply throttle, or just on initial 0 - 50+% opening?

 

Sam

 

Will have a new video up soon which demonstrates it well. Generally, it's after a dose of full throttle, you come off, then re-apply and find there's nothing. Sometimes she coughs and then runs fine, sometimes you have to stop, knock it into neutral and rev the engine, then it's fine. It is quite baffling.

[Noel Tidybeard]

that almost sounds like the accelerator pump on the carb is intermittent in operation

[red5]

That's what I suspect...

 

Either hole in diaphragm or crud behind it.

 

Can you see down carb relatively easily? The tube from the acc pump should exit into venturi beneath the choke flap and above the throttle flap - relatively easy to see if a rapid opening of the carb results in a uninterrupted 'squirt' onto throttle flap.

 

No engine running required 

 

Although a full-ish float chamber is needed for obvious reasons....

[red5]

No. 40 and 28/29.

 

Apologies if it's teaching you to suck eggs chap.

[dollywobbler]

Accelerator pump is working fine. In fact, when it loses power, it's only the accelerator pump that keeps me going (cue much frantic wrist action, oo-er...)

[red5]

Hahha, spat my tea out....

 

Float level ?  - or needle valve sticking?

[dollywobbler]

Could be. Can't say I really understand enough about them to know how to check. Will be getting the carburettor apart again at some point, but probably not for at least a week.

[madrat]

I would do a full carb re build

[dollywobbler]

More video, more speed.

[plasticvandan]

Assuming flow to carb is OK,I would say the float level is too low,and its shutting off too early.Similar carb as that used on Regals, I used to have a cutting out problem due to the carb flooding internally due to the top cover gasket not sealing properly.

[Coprolalia]

Stupid question probably answered or considered previously, but what state is the carb on TWC's original engine in? 

[red5]

The symptoms seem to indicate a sticky float needle valve. Sticking open when you come off the throttle.

 

Maybe?

 

Ben

 

Sticking closed I suspect - open would flood it/leak like a sieve.

[dollywobbler]

The symptoms seem to indicate a sticky float needle valve. Sticking open when you come off the throttle.

 

Maybe?

 

Ben

 

If it was doing that, I wouldn't expect a swift cough to clear it. Not that I'm an expert on carbs.

 

 

Stupid question probably answered or considered previously, but what state is the carb on TWC's original engine in? 

 

Sadly, the spare carb was already missing its top and had been open to the elements, so not much cop.

[AndySnapper]

Fuel starvation slightly overcome when you blip the throttle, then clearing after a short break to let the crap (wherever it is) settle and start over again?

 

Does it have a clean fuel filter in-line?

 

I presume the fuel line has been replaced so no splits or leaks?

 

You say there is petrol around the outside of the carb? This is especially worrying given the tendency for these vehicles to catch fire back in the day.

 

Stripping the carb and re-building is pretty specialist I bet (last resort).

 

What about the air filter blocking flow?

 

I don't envy your job to find the cause DW but do wish you all the best.

 

Andy