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1147 idling issue followed by low power


Valherald
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Hi guys

A few tips if you don't mind as I'm sure some of you must have had the issue!

 

LITTLE BIT OF BACKGROUND:

1147 Herald which I got back on the road 500 miles ago has been running perfectly as I have gradually increased the distances, speeds and time of trips. slightly longer trip last week on the M way so higher speeds than normal and a longer trip, all went well, nice smooth running.

 

ISSUE:

Once off the motorway,car started stalling when pulling up so no tick-over every time I pulled up. After a couple of roadside stops and some tinkering with the volume adjuster and tick-over screw, all was back to normal and the trip back was as smooth as the one out.

 

I have taken the car out this week and instantly, the tick-over issue has returned and the car running generally rough.

 

ACTIONS SO FAR

Checked compression's, all good

Re-adjusted the tick-over and volume adjusters

Replaced soiled fuel filter

Replaced (very soiled) air filter (which also smelt very fuel rich)

Adjusted timing which appeared to be slightly out

Removed & cleaned carb mixture jet

Checked points gap

Checked plugs gaps (rich deposits on plugs)

 

CURRENT SITUATION:

Tick-over now good when warmed up and choke pushed full in

 

ISSUE:

Car is now very under-powered compared to previously, particularly at the higher speed end, 50mph, doesn't want to go any higher with foot flat to the floor and it was slow getting to that point.

 

OBSERVATIONS:

Some back-firing and carb popping when accelerating and slowing

Temperature good and stead

Oil pressure good

Vacuum same as previously was 

 

NEXT STEPS:

Any thoughts welcome guys and gals but do you think I'm right to be looking at:

Carburettor

Fuel delivery

Re-looking at the timing

 

Like I say, any assistance, thoughts, ideas very much welcome.

 

All the best

Gary

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Thanks Clive, do you know what, it was when I initially had the tick-over issue but Im not sure that it was on checking last night! I will check this afternoon but if it isnt, would that be a vacuum issue?

Thanks for the tip.

Gary

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you can test the  dizzy vac capsule for leaks by short tube and suck like crazy you should see it move the base plate. 

if its holed you just suck for ever .

the vac capsule only improved economy no effect on acceleration or power overall. unless the link to the base has broken and the base plate  is floating without control.

 

there are a lot of new condensers and rotors which fail the rotors short out the HT to the dizzy spindle and the condensers have 3 ft of foil inside instead of 20ft.  failed condensers normally create backfires and whilst it will idle it wont rev without a hole lot of serious misfiring 

Pete

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Thanks Pete

Well, that makes a whole lot of sense but as always, I have everything spare apart from the part I need, no condenser!! I cant get hold of one until Monday but I did get a new 'decent' rotor which when compared to the one on the car, backed up your comments about quality for sure, loose fitting body and very loose contact plate so you may well have hit my problem on the head.

 

I will let you know on Monday but thank you and Clive for the tips as I would have probably ended up getting myself into all sorts of Carb work and problems this weekend :) 

 

Many thanks

Gary

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if its a lucas dizzy get a red rotor from club shop or distributor doctor,  

 

delco rotors are less problems with crap suppliers

 

its a classic,  there's always another job to add to the endless to do  list

chasing your tail with a few enjoyments in between   

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My Herald 1200 went through a phase of refusing to idle, but ran OK with the accelerator in use.  It's got the Solex B30PSEI Carburettor.

 

There's a brass nut at the top of the carburettor, facing out towards the bulkhead - The Pilot Jet.

 

If you find Solex technical leaflet 878 on the 'net, it's item 12.

 

It had worked slightly loose and must have been upsetting the idle mixture.  I discovered this accidentally by poking it with my finger and all came good.  Confirmed my theory by placing a large blob of Blu-tac over it.  For some reason the head was quite mangled and better carefully tightened with a socket/spanner than flat blade screwdriver.

 

I'm not an expert though!

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My distributer comment referred to the advance weights under the baseplate. If they are seized the timing will not advance giving poor power and economy. Vac advance is there to give better cruising torque/economy. But disconnect the vac pipe when checking for mechanical advance.

 

Once running ok, I strongly suggest setting timing by ear. The factory figures are not going to work as fuels are so very different today.

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Thanks guys

Thanks Stuart, I looked at that and made sure it was tight in, took it out and cleaned then popped it back, glad to hear mine isn't the only one slightly screw driver damaged!!

 

Got that Clive and Pete, I will be jumping back on the issue Monday evening with the spare parts and the checks above, will keep you posted.

 

Thanks for all the support.

Gary

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Many thanks guys

All fixed and running better than previously.

 

Thanks Pete, I think your diagnosis and reasons behind it were bang on, by the way she ran tonight I recon the badly made rotor has also been causing some lumpy running, backfire etc.

 

Great support thank you.

Gary 

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Can anyone point me to a good youtube video for setting up carburettors. I have got my Spitfire to start after 21 years but am unsure about cleaning and setting up the carbs. They are the SUs without the breather pipe from the rocker box. The engine runs but only on choke at the moment, obviously sooting up the plugs and far from ideal. Can't even get it to my normal garage to have set up and tuned at the moment. I have absolutely no experience with carb set up as this was done by a relation who was a mechanic years ago. Spitfire is a 1972 with a herald 13/60 engine....don't ask!!!

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Thanks for that. I was advised to take off the air filters and while the engine was running spray carb cleaner into the air intakes to get rid of any evapoarated petrol residue and other crud, to prevent having to strip them down! I haven't tried it as yet. Have you experts got any views on this please?

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A number od simple things

 

with the cleaner off it improves access but need them on to get the mixture correct

 

with them off remove the dash pot piston and raise the air piston with fingers or anything

let it drop it must land hard with a clunk.

 

if its not the slide inside may need a clean and a dab of oil

 

mostly any sticking here is because the needle is fouling the jet , this need jet centralisation

undo the big nut under the body, the highest half a turn,

screw the lower adjusting nut till the jet touches the bottom of the piston, jam a screwdriver down the dashpot tube to hold the air piston down,

tap the jet holder , test the drop , if it clunks nip the top nut up

 

back off the mixture jet nut , the lower one 2 full turns this should give a basic running to start up

 

if the cars been standing for months its worth remove the float tops and with a small tube and goggles

And air piston top cover and piston removed blow down the jet make sure it blows back into the float area

hence goggles needed.

 

also remove the float needle valve make sure no debris is hiding in the supply line and blocked the back of the valve.

 

when you pull the choke make sure when its pushed back in the jet does pop back up to its adjusting nut a prod with the fingers is all thats needed these can stick and you run on full choke without realising

 

if that makes sense have a look see let us know if you find something

 

Pete

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Doug. Just passing on what I have been advised to do! Not sure if it was good advice, hence me asking as you and Pete appear to talk sense and know what you are doing.

Pete. Will give it a try. Can only mess it up and as its going to the garage eventually for MOT if I really screw it up they can have a go. I am told that some of the mechanics there are old school and know about proper engines.

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if you can make meccano or even leggo,  read a book    you can strip a carb.

 

theres little to go wrong if you stick to what doug says and ignore me or the other way round,          neither of us are sane 

 

if unsure of what you have do one at a time and take photos or make a sketch of anything you remove 

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Gents... Sorry to ask awkward questions, some very obvious, but when it comes to engines this is my first attempt on my own. How do I find out what type of SU carbs are on my engine and why do they not have breather tube connectors like some of the other models. My rocker box has a breather pipe outlet which looks to have been spraying a fine mist of oil over the back of the carbs for the 10 years when I was previously running the car, but should this be connected somewhere and if so, where? The carbs have tags with AUD257 F & R (front and rear)

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AUD257 are the correct HS2 carbs for the Spitfire Mk 3 (if the tags actually are on the right carbs).  Obviously they are best suited to a Spitfire engine but should be okay with the 13/60.

Different models, different carbs, different breather arrangements.  Breather could be sorted out later (if it was okay for 10 years it will be okay for a bit more.  Best short term option is to fit a hose venting down at the bottom of the engine bay. 

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