Car not starting after rebuilt

[SeanG]

Hello everyone, I finally got everything ready for a test ! but unfortunately it s not starting....

 

I have test a spark and there is one ! I have also checked i m not 180 out by checking TDC without rocker cover. so all good for ignition.

there is fuel in float chamber and when i try to start the car the plugs smell petrol, they are not fully wet but just smell petrol.

also when i put carb cleaner inside the mouth and try to start, the car almost fires then die.

 

so my theory is :

 

1- the fuel in my car being 9month old is not burned, but then again 9month is ok right ?

2- i have a problem with needle

 

what do you guys think ?

 

thx a lot

 

 

Sean 

[Unkel Kunkel]

OK ,Let's take that you've got a good spark and that it is happening at the right time

This is also  supported by the fact that it fires  up  briefly on your carb. cleaner  ( Bradex Easy Start best)

This suggests not enough petrol reaching cylinders.

 

 

So,1) is it reaching carbs ? 

Test this - detach fuel line from fuel pump  and point it into a jar, away from any sources of spark ie detached plug leads and spin engine over ( I presume still has the mechanical fuel pump -should get a good spurt of fuel.

If not, then given fuel in tank ,have a look at the fuel pump- they can hold an extraordinary amount of debris even blocking the filter screen. 

 

Having ascertained it is getting to  the carbs

2) is it getting into into the carbs?

for this your best dismantling and cleaning everything out especially the needle valves (with any carb cleaner you have left)

Fuel

a)It is quite possible  that the carbs will be fouled up with residue especially if laid up long time.

b)Fuel is  very "old" at 9 months.You used to be able to get away with this but recently  it goes off/stale quite quickly and the ethanol in it absorbs water and can speed corrosion -a real issue with garden machinery where the advice is anything over thirty days old can be  seen as  suspect.It also gums up  forming a sticky jelly like residue ,or a varnish ,or jelly with gritty white corroded  bits in it  ( I had to strip down a carb on a mower yesterday which I put away in November without bothering to drain the fuel and it was quite  impossible to start until  new fuel  and carb.  fully  cleaned out...)

 

Good Luck!

 

Andrew

[dougbgt6]

Sean, I notice you have an alloy rocker cover and the breather pipe only attaches to one carb. There should be a T piece and both carbs connected. Also, as there's no flame trap in the rocker cover, shouldn't there be canister like the earlier models had? This is probably nothing to do with you're current problem but I thought I should mention it.

[Steve C]

That sounds very much like stale petrol to me. If it is trying to fire on carb cleaner it clearly wants to go, but the fuel it is getting has lost most of its volatile component from evaporation. As Andrew suggests, the other possible cause is that it is not getting from the float chamber into the carb venturi and into the cylinders, but I would expect to see some over-fuelling at the carbs and leakage if the pump was fighting a blocked needle valve or similar?

 

Keep plugging away at it methodically, you will get there!

 

Steve C

[SeanG]

so i double check ignition, gap is ok, and the cap is pointing cylinder 1 at TDC on 1 (when valve 1&2 are rocking) re checked with a spark tester and still get a spark !

 

the plugs are still dry... they smell petrol but ther not dripping, could it be there is no vaccum ? 

i opened the float chamber and petrol leaks, it s full, so doesn t matter if it s a fuel problem pump right ? as long as it s full .

thx for help, very strange....

[Unkel Kunkel]

How frustrating!

Observations :

1) The plugs are "dry" 

After (I suspect!) some prolonged cranking on choke I would expect them to be dripping.

2) you consider is there some lack of vacuum

 

Also consider again dougbgt6 's observation re the pipe work.:

 

On engines after KE 10,000 the crankcase ventilation was revised:

-The Smith's emission valve was no longer used.

-The central manifold tapping previously used for the emission vac tube was now used for the servo vac connection.

Now each carb had a vac tube which ,after merging at a T tube led to the rocker cover.

 

 

Looking at your pics,I can see the servo connection to the central portion of the inlet manifold - that's what  one would expect.

and I can see a vac pipe coming off the rear carb (I cant see where it goes for sure but I suspect it leads to the rocker cover)

 

However,

1)I can't see a front carb vac. tube

2)I can't see a T piece

 

If the front carb vac connection is  simply open   this certainly will be an inlet leak.  If the rear is unconnected this would further aggravate the situation compounded by   stale fuel..

 

Hope it helps,

 

Andrew

[dougbgt6]

Andrew, additionally after KE10000 there is a different rocker cover incorporating a flame trap before the vent. The alloy rocker covers don't have this and people who fit one to a post KE10000 also re-incorporate the smiths valve.

 

Sean, lack of vacuum is a possibility, I had a leaking manifold gasket which produced very similar symptoms.

[Pete Lewis]

the pics are before and after rebuild ? 

 

Srombergs have 2 breather plans a  smiths valve direct to the manifold,  up to KE10000E   the vacuum take off  Tee'd to  strombergs was introduced from KE10001E

so should you have a Smiths  Valve or Tee set up ???

my guess the carbs dont have a vacuum tube for the breather and a dying smiths valve has been removed long ago and the breather let out to under the car  ???

 your 1st pic  pre rebuild  looks like the breather pipe  just dives under the manifolds 

 

if the pic is of what your are trying to start then the Vacuum  servo take off is open and need connecting or blanking.

 

Pete

[Casper]

 

 

the cap is pointing cylinder 1 at TDC on 1 (when valve 1&2 are rocking)

 Am I missing something, or is this not at the end of exhaust stroke and beginning of intake stroke ?

 

C ?

[SeanG]

Hi casper, yeah when i m at tdc on 1, if i rotate engine slowly, both valves are rocking after tdc, wheras valves on no6 don t move.

 

Corrcect ? ????

[Pete Lewis]

on compression stroke they must be a gap under each rocker , if they are rocking it looks like youre 180 out  you want 11/ 12 rocking   

 

old trick is remove plugs stick someones thumb over No1 plughole, turn engine slowly till air is felt to start to escape past thumb, so youre on compresion stroke, now

turn slowly to align your TDC pointer,   look at rotor it should be pointing at No1 lead

 

Pete

[SeanG]

**** UPDATDE ****

 

So ! regarding ignition, is was good on TDC, then i ran out of idea so went 180 out (just in case:-) ) but now when i put fresh fuel into the plug hole, the car start for 10sec then dies.

There is fuel on top of the jet, fuel pump works (i tried with fuel line unplugged at the carbs) but plugs are still dry.

SO I think it s safe to assume I have a vacuum problem right ?

 

Also I have put back everything the way it was when i first got the car, it was running (rough) but still.. 

[SeanG]

Solved ! It was vacuum leak, I have blocked both carbs breather and inlet manifold, just let breather on rocker cover and the car started !

Idle strangely but works, I m gonna received the T piece etc to plug both carbs breather to rocker cover.

 

Do I need a PCV valve ?

 

thx all 

[Pete Lewis]

With breathing direct to the carbs theres no need for the valve, its only used if breathing goes direct to the manifold.

 

pete

[dougbgt6]

Pete, I'm confused (no change there) what is the fire trap for? (under the square block on the top of the rocker cover) I've been told if I change to a cover without one I have to have the valve?

 

http://www.canleyclassics.com/triumph-gt6-mkiii-cylinder-head

[Pete Lewis]

Doug,  

the gauze fire trap was introduced on many cars of the era, bit like a davey lamp it stops any fumes in the crank case igniting fumes in the carbs and visa versa

 

always bets to have one , doesnt affect much if you havnt,

 

what you dont want is a unknown  didnt know i had one  gauze thats blocked and you build crankcase pressure,  found plenty of blocked ones in the coarse of time.

 

many cars had them extenal like Hunters etc.  of the day   as an offset outlet drum full of nylon gauze,  it was found metal gauze could break up due to vibration

some  had  perforated plates in a canister,

mk1 cavalier/opel were magic at blocked gauze in the rocker cover 

 

hate the stuff myself.

 

Pete

[Unkel Kunkel]

I was having similar thoughts, dougbgt6

 but  most   impressively, Pete has answered my question before I asked it !

 

Andrew