rough running

Post by **steve4063** » Wed Oct 03, 2007 1:55 pm

right

engine is running really rough
put new advance tube on thanks to dave for spotting that

done the timing with a light bulb to get it running and i had to turn it clockwise quite a lot to get it running ok ish without backfiring

it ticks over ok ish but as soon as you try and pull away it's VERY gutless

any ideas wink:

Post by **bmcecosse** » Wed Oct 03, 2007 2:30 pm

Need to check if mech advance inside the dizzy is moving - and is the vac advance actually doing anything - suck and see. Otherwise - usual checks - compression test/valve gaps/air leaks/carb - oil in damper/mixture anything like correct .

Post by **steve4063** » Wed Oct 03, 2007 2:36 pm

sucked on the tube and bits move in the dizzy.
oil in the damper all seems ok
can't see or feel any air leaks all new gaskets with gasket seal as well

mixture unsure as its running so rough
tried what dave suggested.
meter on coil leads turn engine until piston/rotor arm at no 1.
turened dizzy until it just breaks contact check nothes on pully wheel about 4 degrees

start her up runs rough tried advancing and retarding no change at all.
apart from cutting out it just won't run right sounds like its blowing through the exhaust popping all the time and no power.

been doing this all morning and still no change

Post by **bmcecosse** » Wed Oct 03, 2007 2:43 pm

Sure the plug leads are correct order - 1342 ? Or - is it an oiled plug - or valve gaps open/valve burned/no compression because of broken rings/piston.

Post by **chickenjohn** » Wed Oct 03, 2007 2:49 pm

If its REALLY rough and gutless and ignition and fuelling seem OK, then I'm afraid that points to a blown head gasket, between the cylinders. Do a compression test!

Before doing that, have you had a look inside the carb? maybe the outside of the piston/inside of dash pot are dirty and sticking. A clean here can work wonders. Gutless running- are the points closed up or too wide? check with feeler gauge.

Post by **steve4063** » Wed Oct 03, 2007 3:08 pm

done a compression test yesterday
1 was 8
2 was 8.5
3 was 7.5
4 was 8
so all within the ranges.
i just pulled the lead off one at a time and 1,2 and 4 made a slight difernce but 3 didn't seem to make much diference at all

checked plug gaps all 0.025
points 0.015

1,2 + 4 were very sooty but 3 had a little oil on it.

Post by **Orkney** » Wed Oct 03, 2007 3:20 pm

have you got new petrol in the tank ?

Post by **chickenjohn** » Wed Oct 03, 2007 3:26 pm

Good point, 20 year old petrol can give rough running!

Simple one- have you got two of the plugs on in the wrong order?

Sticking valve gear- take off the rocker cover, turn the engine by hand and make sure all the rockers etc depress the valves as they should.

Pitted points? dodgy dizzy cap or rotor? work through everything systematically.

Post by **kennatt** » Wed Oct 03, 2007 3:29 pm

you could try adjusting the carb to basic setting IE screw the jet right up and then turn it out counting 12 flats this puts the jet at about the right setting then play about with that, one or two out and back ,might just get you somewhere near,looks as though youve tried all other obvious things Good luck

Post by **steve4063** » Wed Oct 03, 2007 4:08 pm

new plugs points rotor dizzy etc etc
tried doing mixture 12 flats or in the middle

new petrol changed coil

just rung a tune up friend of mine (very good at what he does)

he said sounds like tappets are too tight ...... or faulty condensor even tho it's new

so gues what i'm doing in the morning checking the tappets.

any tips on an easy way to do it

Post by **bmcecosse** » Wed Oct 03, 2007 4:13 pm

Try some different plugs first - sounds like duff plug - or duff HT lead/dizzy cap! Change them all! Condenser won't affect just one plug - and I told you to check valve gaps a while back - it's only minutes to whip the cover off and check them!! however if the comp check is ok - then the gaps will be near enough. The readings you give are not 'good' - especially #3 - but they should be ok to run.

Post by **steve4063** » Thu Oct 04, 2007 8:53 am

adjusted the tappets
they were tight about 10 so adjusted them to 12 now
still no dif tho
altho it did start frist time this morning very cold and wet here as well.

should be sunny later tho

one thing i have thought i'm using unleaded and normally it's not a problem i'll try and get some additive in a bit when they open at 9
maybe that'll cure it u never know i did have a toyota once on taxi's and it wouldn't go above 60 because i was using unleaded popped the original 4* in and it went beautiful

Post by **chickenjohn** » Thu Oct 04, 2007 9:14 am

One thing you haven't done which (IMHO) is a must on any SU equipped car when you first get it is to strip the carburettor down and clean it thoroughly. Especially the inside of the dashpot and the piston. Be careful not to bend or scratch the needle!!! you can then examine the SU mixture needle for a wear ridge- if it has one get a new needle and jet.

The SU carb in generally very reliable and rarely needs cleaning but when it does it can seriously hamper the performance of your car because the piston and needle cannot rise and fall freely as they should. The needle in the jet determines mixture, allowing more fuel to enter with higher revs and hence more inlet vacuum, the piston in rising also lets more air in.

Clean all the black carbon and dirt off with thinners, petrol, wd-40 etc and a soft cloth (dont use abrasives!)

While you're at it- change the air filter- in fact do this 1st, I've seen a few mysterious running problems caused by dirty/ blocked air filters recently.

Post by **steve4063** » Thu Oct 04, 2007 10:24 am

new filter already....

i cleaned the carb yesterday with carb cleaner half a tin in fact and put redex actually in the carb while it was running to help also.

and tried to spray carb cleaner in car doesn't like that and stopped.

spoke to rob (tech) he suggested disconectinf pump and see if it runs ok just before it runs out of petrol to see if fuel valve it worn but nope it still run rough until it stopped no change.

he did say if its running like that its more than likely fuel as timing will run with such a wide angel.

this is bafflin me completely

so annoying

Post by **Orkney** » Thu Oct 04, 2007 10:32 am

and the fuel pump is ok? points etc? remember neil had a rough idling prob up here on the LEO and that was stubs of fuel pump points.
shame you cant borrow another pump and at least eliminate that - it still could be worth replacing the petrol - incase some idiot peed or put sugar in the tank etc.

Post by **chickenjohn** » Thu Oct 04, 2007 10:40 am

I have another idea! Check the breather system for leaks, a perished hose or rotten rubber disk in the mushroom in later cars could cause air leaks direclty into the manifold causing rough running and gutless power. Also do you have the correct oil filler cap- some act as an inlet breather for the crankcase ventilation. (Wille posted a list of the correct breather configurations a few months ago).

Does the car burn oil?? Low compression, gutless power delivery, uneven idle could simply mean the engine is knackered, REALLY knackered.

Is there silt in the carb float chamber? maybe the pipe to the jet is partially blocked. Clean fuel filter in the pump as well.

Post by **steve4063** » Thu Oct 04, 2007 11:38 am

pump is ok checked with a spare as well as new points.

new petrol completely it ran out yest so another £10 in it. this morning.

i have balsted carb cleaner through so hopefully it's all clean inside.
iu just went down for mot but he can't do it because dvla haven't any record of it yet as the club have taken a long time to sort the forms out and now we have a 4 day post strike

so it'll be 2 weeks before i can get it done

i'm meant to be going to devon sunday to pick the next one up but i've no room so i can't now.

while i was in the mot tho my mate the tune up guy came in as they're all friends.
he walked in and said thats not right it smells strange.........
he sugested head gasket between 2 ports ie why there's no gunk and still good compression.

so i'm changing that today/tom and while i'm there i'll check every bit of it to makle sure it's ok anything i should keep an eye out for

Post by **chickenjohn** » Thu Oct 04, 2007 12:27 pm

That was my 1st thought
"If its REALLY rough and gutless and ignition and fuelling seem OK, then I'm afraid that points to a blown head gasket, between the cylinders. Do a compression test! "

BTW, you need to actually dismantle the major components of the carb to thoroughly clean it. Blasting carb cleaner through from the air filter side is not enough. Undo the 2 screws and remove dash pot and piston for cleaning.

Post by **bmcecosse** » Thu Oct 04, 2007 1:29 pm

But gasket blown would not give these reasonable comp readings - the two blown ones would be low. Are you SURE you hav th plug leads 1342 anti-clockwise round the dizzy? And have you tried a new set of plugs - I struggled for ages with mates MGB - he said it was relatively new (NGK) plugs - eventually - I fitted a new set of Champions I had with me - completely sorted his rough running/misfiring/backfiring.

Post by **steve4063** » Thu Oct 04, 2007 3:09 pm

yes leads def
1 3 4 2
and brand new plugs i done a complete service with everything new

as for comp i said about that and he said the one he had the comps were ok it has blown between the 2 cylinders so hadn't altered the comp just the running