Essex V6 3.0 Not firing on 1 and 4

[Ellis Dee]

Hi Guys,
I have an old Essex v6 3.0 engine in my Triumph Stag. I had the engine rebuilt recently but at the moment if I pull off spark plug lead 1 and 4 there is no drop in revs. I've checked all the obvious, dizzy, spark and leads. I'm getting about 130 psi in each chamber which I know is a little low but because they are all the same I'm not worried. I took the offending plugs out and they dont smell of petrol at all which leads me to think that no petrol is getting to cylinders 1 and 4. The carb is less than a year old but when I fitted it I dont remember seeing the "W" piece that I know some people fit!

I was wondering if anyone else has had a problem like this and do you think that fitting the "W" bit in the carb may sort it?

Thanks in advance.

[996TT02]

Did you check whether the plugs are actually firing? Connect lead to a spare plug and earth to engine block (and either stand clear or use insulated gloves to grab only the lead...)

I don't know much about this engine's carb but I find it odd that a single carb could only selectively supply fuel.

[Ellis Dee]

Hi Yes,

I have one of those inline leads with the light in the middle so it seems the spark is there. Maybe I should actually take the plug out to see if it sparks!

[DonkeyApple]

It seems on odd one. You've got spark. You've got enough compression and it's hard to fathom how a single carb wouldn't be feeding all cylinders.

How is it actually running? Is it running rough and down on power and when you pull those two particular leads off it just feels in tickover that they aren't making any difference?

If you've just had a recent engine rebuild, has the rough running been since then or appeared later?

Could it be that whoever put it back together just got the order of the leads wrong?

[Ellis Dee]

Its baffling me. It is running really rough but like I say. When I take off cap 1 and 4 that are both at the front it doesn't make any difference.

I thought the firing order may have been wrong but I checked that and its all as it should be!

[markymarkthree]

Mine is the same on tickover i can take a couple of leads off and it still sounds ok, rev it and it and it sounds stifled.
I would put the W plate in as it is there to spread the fuel and it could cause a bore or two to run weak and overheat.
£80 for a W plate from Webcon.

[gazza285]

Whip off the rocker covers and make sure the valves are opening? Check the valve clearance while you are in there.

Check the plugs are good, you might have sparks at the lead end, but that doesn't guarantee you have a spark at the tip.

What the hell is a "W" piece?

Edit...

Edited by gazza285 on Friday 14th January 18:26

[Krikkit]

I can't see that stopping two cylinders from running dry...

[Ellis Dee]

I’ve check on the base of my carb and it doesn’t have a pipe coming off the side like the one shown. Does it go to the rocker cover somewhere!?

[markymarkthree]

Ellis Dee said:

I’ve check on the base of my carb and it doesn’t have a pipe coming off the side like the one shown. Does it go to the rocker cover somewhere!?

Yes it goes to the engine breather on the o/s rocker cover.

[markymarkthree]

Krikkit said:

I can't see that stopping two cylinders from running dry...

It stops 2 & 5 gobbling up most of the fuel.

[andybracing]

back in the day they used to suffer from inletmanifold gasket leaks, might be worth checking for that, spray something aroung the manifold, carb cleaner works well, or brake cleaner, just makesure none gets sucked into the carb or it could be misleading

[gazza285]

Krikkit said:

I can't see that stopping two cylinders from running dry...

A trio of DCNFs or IDAs would surely be the PH solution?

[tight fart]

Have you tried a new set of plugs, or just move the plugs around to see if it that?

[Penelope Stopit]

If the engine previously ran ok without the W.....

Why is a W now needed?

That is the question

[oakdale]

I doubt the lack of the w plate is causing your problem, has it run like this since the rebuild or was it ok at first?

Does it fire on all six at higher revs and when being driven?

[DonkeyApple]

I think a little more info is needed re the running. The original post doesn't actually say there's any issue with the engine at all just that the OP notices no real change on idle if a couple of leads are taken off.

Obviously there is an issue that inspired the OP to consider removing plugs but there isn't actually any detail at all as regards what that was.

[stevieturbo]

So was it running right before the rebuild ?

Has it ever ran right since the rebuild ? And why the rebuild...whatever that entailed exactly ?

Are you sure the carb is installed correctly, and all hoses etc on the manifold etc ?

[DonkeyApple]

If compression is 130 all round then it sounds like it was just head work rather than a rebuild? But some info on what the actual issue is from the OP would be the best starting point.