Won't start after rebuild

[Terry w]

Hi this is my first post been years rebuilding my stag, all back together but can't get it to start
The engine has been rebuilt new crank, rings, timing chains, both heads unleaded conversion new carbs
Timing checked over and over again fuel comming through fuel in the manifold but dosent seem to be getting through to the cylinders any suggestions more than welcome
Cheers
Terry

[Kevin Garrod]

Simple stuff first, are you getting a spark? Oh and you are timing off No2 cylinder?

[dasadrew]

Fuel in the manifold but not in the cylinders?? Have you removed a spark plug or two and seen that they are dry or drowned?

Drew

[davidf]

"fuel in the manifold but doesn't seem to be getting through to the cylinders"

How are you identifying these conditions?
If there is fuel in the manifold, what is pulling it through? There must be an induction stroke sucking through the carbs unless a carb is leaking.

[Terry w]

Thanks for your comments
First timing is set no 2 cylinder at 14 deg before TDC
Good spark on plugs
Fuel getting through to carbs
When I remove the carbs I can see fuel hanging in the manifold
Spark plugs found to be dry after attempting to start

All suggestions welcome

[dasadrew]

It might sound dramatic, but if fuel is hanging there and not being sucked in to the cylinders at all, it seems to indicate that there is no 'vacuum' (lower pressure than atmospheric) in the cylinders. Sorry for the drama (and sincerely hoping someone might have a less dramatic diagnosis!), but are you sure the valve timing and valve clearances are ok? Can you measure the compression on the cylinders (only requires engine to be spun at starter motor speed).

You could also try to hold your palm (or paper or whatever if you're a scaredycat!) over the air inlet of the carb when you spin the engine to see if there is suction there.

Drew

[jpyke]

Thanks for your comments
First timing is set no 2 cylinder at 14 deg before TDC
Good spark on plugs
Fuel getting through to carbs
When I remove the carbs I can see fuel hanging in the manifold
Spark plugs found to be dry after attempting to start

All suggestions welcome

Just a thought - you're set up to No.2 TDC, but is this of the power stroke? You can end up with the distributor timed 180 degrees out...

[Arbman Al]

I don't know if this is even possible, but have you got the breather and fuel pipes connected the right way around on the carbs?

[dasadrew]

Just a thought - you're set up to No.2 TDC, but is this of the power stroke? You can end up with the distributor timed 180 degrees out...

Good check to do in any case, as also firing order! However, wouldn't the plugs be drenched in fuel if that were the case? The OP says the plugs are dry.

Drew

[Kithmo]

But are all the plugs dry, or did you just take one out ?
Does the engine sound like it's huffing and puffing on the starter motor or just a constant whining ? (no compression, maybe valve timing ?)
Are there any signs of firing at all or nothing ?
Is the fuel new and clean ?

[marshman]

Assuming all the timing (valve and ignition is correct) and the carbs are basically OK, plug leads on in the correct order then it should go, or at least do something. However, if the engine has been rebuilt and has stood around for a while it may be lack of compression due to the rings not sealing against the bores. Remove all the spark plugs and put a squirt of oil down the bores to help with the initial sealing. Replace the plugs and try again.

This happens on the older jag V8's like those in the XK8, if they have been standing a while they sometimes won't start due to lack of compression, a quick squirt of oil in the bores and away they go.

You could of course do a compression test but if the engine has been rebuilt and stood a while I would just squirt a bit of oil in the bores.

Roger

[dasadrew]

When you finally get it running, tell us what the "unleaded conversion" is please.

Drew

[Lingen]

Drew.
I think I can guess!
Mike.

[Ferds]

Have you checked you haven't got the timing 180 degrees out?