11 replies to this topic

[iwatkins]

Typing in tiny box, so hope this comes out OK.

Failed today on emissions and a ball joint.

Emissions was 8.2% CO, HC was well within limits.

I had spent ages setting it up and was running very nicely. But those emissions are obviously to high.

What to check? I followed Haynes setting up the carb.

Standard 1991 1275cc engine with a HS4 running an AAT needle (for now). Has a cone filter on a stage 1 manifold but an old 3 into 1 collector and an RC40 style exhaust.

When I set it up I had it set so the revs rose and then settled using the lifting pin. So that should be about right.

However, to get a stable idle I need around 1100rpm but Haynes reckons around 800rpm.

So that wouldn't have helped with the result.

Ideas where to start to try and get it at least close. Guys have said drop by anytime to test the emissions before my retest next week.

I do have a newly rebuilt HS4 to put on with new jet and an AAA needle to put on. I was saving that until after the MoT but worth trying?

Cheers

Ian

[A-Cell]

Weaken the mixture screw right off, and try that.

[KernowCooper]

8% is way rich at idle, I would wind in the mixture and keep lifting the pin until it falters, or could you not adjust it at the MOT Station?

[Algordo1100]

It should be a stable idle at 800. If it is lumpy below 1100 you might have an air leak? Some usual culprits are the inlet manifold gasket and hthe vac take off for the brake servo (where fitted) . That might be causing your inefficient burn and high carbon monoxide reading.

Perhaps a leak has caused you to richen up too much to compensate?  Maybe try the 'wd40' trick to check there's no air leak, sort it if there is one and then re-set your mixture somewhat leaner than it is now.

[iwatkins]

Perfect. Thanks guys.

Reckon I'll swap the carb anyway as I've got new gaskets to go on.

I did try winding the jet adjust in to the a good half turn beyond faltering on the lifting pin but that only brought it down to 7.3%. The chap who does the MoT is sound and let me tweak it during the test on the gas bench and he is into his Cortinas.

Guess I'll just start again from scratch. Retest is Tuesday, so I have a week.

On the plus side he did say the car was in great shape and everyone came out and drooled over it, memory lane for most.

Cheers

Ian

[jpd]

i popped some wynns from halfords into mine, and turned fuel down

[iwatkins]

Ok, so stripped the carb off and to be honest, I just know the carb and inlet manifold was fitted by previous owner.

I know this as it was about five different, homemade gaskets and a massive dollop of black silicone sealant.

The abutment plate doesn't even sit flat against the manifold as its catching on the side of the manifold just below where the throttle cable and choke cable are mounted.

So after two hours of cleaning all the surfaces I had the chance to put it back together. That's when I found the problem with the abutment plate. Grrrr.

Anyway, ran out of light so will cut a small section out of the plate tomorrow so it sits flush. Only needs about 4mm taking off a short section.

Got the new carb built up with some initial setup so at least that is ready to go.

Did manage to check the brake servo connection and the breather, they are good. The dizzy vacuum line looked a little ropey so have replaced with new.

So hopefully, bit of grinding later, tomorrow I hope to get it all back together and fired up.

So yet again, previous owner strikes again. Thank you numb nuts.

Cheers

Ian

[iwatkins]

Right, hopefully I have this sorted and probably as an air leak between the carb and the manifold.

It looks as the previous owner had a HIF38/44 on there and pulled it off and bodged a HS4 onto it. The abutment plate and the throttle cable are both HIF types. Another thing I found was that one stud is M8, the other, 1/2".

So, had my new 4" hand held grinder fired up this morning (I love flying sparks) and "adjusted" the abutment plate to sit flat. Nice sunny day so it got stripped of the cracked powder coat back to bare metal and repainted.

Refitted it all with the new carb (has new spindle, jet and AAA needle, stub stack and K&N cone filter) and new gaskets, got it hooked up. Quick prime of the fuel pump/lines and fired straight up.

Let it warm up then did the tune. No lifting pin on this HS4 so had to to the screwdriver on the piston trick. Took five attempts to get the mix right, but 12 flats from flush with the bridge was only 1.5 flats out in the end.

Biggest surprise was a nice stable (ish) idle at 850rpm, before 850 was a severe shake and a stall. So changing the carb, or more likely, removing the crap bodge of sealant, paper and a non fitting abutment plate has solved the requirement of the high idle.

So hoping now that with it just on the plateau at the lean end and running at 850rpm, it'll get own to 3.5% CO. So a very hot run before the retest on Tuesday morning and hopefully it'll pass.

Thanks for the ideas people, appreciate it.

Cheers

Ian

[iwatkins]

Passed MoT this morning, so sorted. 

[Algordo1100]

Passed MoT this morning, so sorted. 

 

Exellent.

[iwatkins]

Yes, thank you very much, you were spot on. :)

I actually swapped the old carb back in yesterday just to check and it also ran fine, so an air leak outside of the carb was the problem. It was the gunge between the carb and manifold purporting to be a gasket. Previous owner for sure (we call him NumbNuts).

And with the new carb and right needle and other bits on, it feels like it has another 100bhp. I could never get over 60mph in 4th. In a test yesterday it got to 80mph in seconds and had way more and would have gone off the clock with no problem.

The car is now how I had hoped. Rapid, smelly, noisy but feels solid. It is actually a car for my wife but I have the hankering for my own one now.

Again, thank you. Pint here for you anytime.

Cheers

Ian

[A-Cell]

Glad it is sorted.