spitting carb

[triumphram]

At my wits end, herald 1200 been laid up for a while due to water loss on last outing. Found the problem to be core plug behind timing cover. After replacing plug I decided while everything was off to change the seal and chain. After putting all back together and on starting up there was considerable spitting from the carb. I thought maybe timing but i have now re-checked it four times, even putting the old chain back at one point.
I set the crank to tdc, then set 7 and 8 rockers to 1.0mm upon 1 and 2 rockers at their top position. Next I turned cam untill 7 and 8 were on the rock, checking the gaps were equal.at this position I refitted the chain with slack on the top side. The marks on the cam sprocket, pully and back plate did line up. re-adjustment of distributer was done lastly and checked with strobe, all ok within a degree or so.

Why the spitting, also on test run, distinct lack of power which to me points back to timing. On start up and idle it's fine, under power or opening throttle awfull. Can anyone advise?

[Pete Lewis]

are you sure you had No1 on tdc firing stroke
I have done the cam timing a slightly different way , the result should be the same but when in difficulty its just an option

this applies to all standard herald,spitfire,vitesse,gt6,bond,2000/2500 4 and 6 cly engines
to check your valve timing is correct on a built up engine to see if the camshaft timing sprockets are where you think they are
This is only for normal standard spec symetrical Triumph camshafts, for fast cams you must refer to the manufactures setting methods.

rotate the crank untill each of the valve rocker numbers 7/8 4pot or 11/12 6pot are at their maximum lift and set rockers 1/2 to have a large gap of 0.040"
having a dial indicator and magnetic base to confirm rocker is fully down is an advantage,
rotate the crank slowly till the TDC marker and pointer are in alignment and check the clearance on 1 & 2 the size of gap is not important, but they should the same/equal

if they are different then you need move the camshaft sprocket to another pair of fixing holes, the holes in the gear are indexed to give 1/4tooth increments there are 4 holes used in pairs and turn the gear over gives more selections

reset the tappet gap to 0.010" on a cold engine when you have finished


did it run fine before you started changing things ?no other oddity in the background lurking ?
simplest is debris in the float needle valve


Pete

[Nick Jones]

Compression test?  Possible head gasket failure due to water loss and head gasket failure between adjacent cylinders may cause spitting through the carb.

Nick

[triumphram]

Okay, there's a few things to check there. All ran ok before i started tinkering done many miles in her, just need to get her well again. Will try the timing check first thanks Peter,interesting thoughts on head gasket failure, will try compression test on all four. Great response thanks for now, will get out and fire the heaters up asap. and report back.

[Pete Lewis]

for comp.  test make sure all plugs are out, the battery is good, the throttle is open,,  even lift  the air piston,

gets as much air in without any restriction , gets the best figures

Pete

[piman]

Hello Triumphram,

another cause, I believe, of spitting back is weak mixture? Do the pistons lift up and drop down smoothly, oil in the damper? The simplest check is to open the choke a bit and see if that helps?

Alec

[triumphram]

just going out to do some checks. Solex carb not su, however will check for debris.

[triumphram]

OK checked carb all ok though i stripped and cleaned all jets and body as a precaution. Done the check with 7/8 rockers and 1/2 rockers being equal at TDC, spot on. still spitting.

What position should the rotor arm be facing when at TDC and 7/8 are just on the rock exhaust and inlet just opening and closing mine is pointing to no 1 contact and the larger notch on the cam end is at 5 o'clock. Have I made a fundamental error and put it 180' out?

I await your input, I feel this could be quite embarrassing!

[Nick Jones]

They won't normally run at all when 180º out - but they will run with two plug-leads swapped around, which could also cause some popping and spitting on top of very rough running.

Nick

[Glenn]

Just a thought - did you use a new inlet manifold gasket when putting it back together?  Are the carb gaskets sealing properly?

An air leak can cause the problems you are describing.  You could spray some WD40 or easy start around the mating faces and listen for a rise in revs?

[piman]

Hello Triumphram,

from what you say number one is set to fire at the right point, do check 2, 3 and 4 are in the right order? Sorry about the carburettor, I assumed S.U.

Alec

[triumphram]

Will probably replace inlet manifold gaskets as this could be the problem, being off the road for so long hasn't helped matters. I have replaced also during the work the plug leads after mine had been eaten by the pesky mice that were living under the dash last winter. I have checked all wiring under and it seems sound, they preferred rubber.Also new condensor and points, fuel pump service kit, oil filter, oil, thermostat, rad hoses, brake cylinders all round, shoes all round, hoses all round, silicone fluid,  Not only have I got a solex but drums all round to boot. Real 50s technology.

[nang]

Don't do what I did  while having a Blonde Moment doing a similar job with my TC. Got the firing order right but ran the leads clockwise instead anti clockwise. It ran, but horribly ! After rechecking valve timing suddenly realised what I'd done. Cheers Tony.

[Glenn]

I'm sure most folks must have got the leads muddled at some stage or other.   ;)

Isn't it amazing how these engines will run on so few cylinders!   ;D

[triumphram]

Update. goodness only knows where it all went wrong. Had enough of timing cover off, timing cover on, timing cover on, timing cover off. Took it to a local garage where 'Old John will fix it'. Indeed he did, he swapped the leads round!!! And mot'd it where it failed on steering bushes (now replaced) and tyre. But why the lead mix up. Surely it should fire 1342. Mine is now running 1243, one being front pot and 8o'clock on distributor. Have I set the timing 180' out, if so should I once again remove timing cover, set pully to tdc, remove chain and turn cam through 180' ? It seems to start ok and ticks over lovely however I'm a little unsure whether to risk a longer run than round the block. :-/

[triumphram]

Hold on a minute, Nang in NZ said he ran his clockwise instead of anti clockwise, I am looking at the top of my distributor and that is how I'm running mine, could I have seriously been doing this for the past four months?

[thebrookster]

You know, come to think of it my spitfire is is the same, makes me wonder now. According to my Haynes manual, leads go on the cap (working anti cloackwise from 10 o'clock) 1, 3, 4 and 2, which it says is for the 1500 engine. However the PO has written it in as 2, 1, 4 then 3 for a MkIV. Then to further complex matters, when I managed to get my coil to dizzy HT lead sorted the other day I plugged the leads back in following both these methods, and could not get the engine to run, however tried it from my memory (which initially I had thought was wrong cause I remembered different to the manual) as 1, 2, 4 then 3.

In fact thinking about it it does make some sense I guess, if the dizzy runs what I shall term double speed, however that still does not make sense for the 4 to 3 spark (i.e. fires 1,moves 180 degrees then fires again.

No,scrap that, it must be timed to fire the spark every 270 degrees on the dizzy. Write the numbers out on a diagram and follow it, using the setup we both seem to have that works the rotor arm fires 1, then moves 270 degrees to fire 3, and so on and so on. Ingenius really, all things considered. ever really thought of it like that before, I have always just taken the leads off and written down positions without considering the workings of it. (and this would mean it is running anti-clockwise as well :) )

Hope this helps,

Cheers,

Phil

[ARH]

turn engine over on starter motor with dizzy cap removed, this will tell you which way it turns, carefull thought there could be a lot of stray electric to deal with.

[don cook1]

With the dizzy cap off and in gear just push car forward to see the direction of rotor arm. Why not look in your manual for firing order. Finger over No.1 (front) cylinder to establish TDC on firing stroke, see where rotor arm is, relative to the dizzy cap and that's where No.1 lead goes.

[Pete Lewis]

all dizzy's   from the 948 upto the 2.5 run anticlockwiswe  

pete