Attempting to start my freshly rebuilt series

[Josh NZ]

Hi everyone.

After rebuilding my series 2a motor (full head rebuild) and reassembly, my truck won't start.

It ran well before cracking it's head and I'm stumped as to why it won't go now.

I filled it with fresh fuel, checked all the leads and cleaned the plugs. Shot some oil down the bores as well just for precaution. I know the carbs getting fuel.

Tried turning the motor over on the starter but that's all that happened.. No catching or sputtering.

Does the occasional backfire through the exhaust and out the carb but it's very sporadic.

Any thoughts? I'm stuck!

[secondjeremy]

Are you getting a spark? Could be points have corroded wile the thing was inactive and need cleaning and re-setting. I'd check the spar - if none check the low tension wiring to make sure nothing has been dislodged then do the points.

[Josh NZ]

I haven't explicitly checked for a spark, but I figured because got backfires I must have a spark somewhere ... But I will check anything slightly suspect!

[Tanuki]

Spitting back through carb/exhaust sounds like you've got ignition taking place on the intake- or exhaust-strokes.- check that you've put all the HT leads back on in the right sequence!

It's easy to do, trust me. I once managed to reassemble a V8 with all the HT leads sequentially 'off by one', which took several flattened batteries to identify.

[Snagger]

I was going to suggest the very same thing, or the timing is significantly out.

Make sure you have no air leaks into the inlet manifold - I had all manner of problems on our Lightweight, rebuilding the fuel and ignition systems, replacing the exhaust, manifold and gaskets, carb and temporarily fitting a whole new ignition. It transpired to be the emissions control PCV valve (a funnel shaped unit between the rocker cover breather and the carb) that was still malfunctioning, despite rebuilding that too, letting air bypass the carb. The resulting weak mixture caused running problems that included backfiring.

[Josh NZ]

Cheers for your timely replies! I checked through all my ignition system and fuel system, it's turned out to be the fact that I didn't think to touch the valves and tappets. They were freakin miles out!

Began adjusting them, and 5 out of the 8 adjusted well, but 3 wouldn't adjust far enough out to allow me to get a feeler gauge inbetween. Aka they are still ever so slightly pushing the valve downwards.

I tried turning the motor over and got a lot more response but it didn't fire, just sputtered a lot and it sounded like at least 2cylinders were igniting. I'm hoping that the last 3 valves will allow to motor to function properly so I can finish the project (for now).

Any ideas on how to get the last tiny bit of the clearance from between the rocker arm and the valve head? Do I need to grind the top little raised bit of the valve?

[secondjeremy]

Sounds like a bad case of valve seat recession - which is a consequence of using non-leaded fuels in an engine designed for leaded.

Only answer is an unleaded conversion - which involves fitting hard inserts to the exhaust valves and special exhaust valves. Engine re-conditioners will know all about this.

[Josh NZ]

Ah, should have mentioned. It just had that, the only original part in the head, is the head itself. All other bits are brand new, that's what stumped me

[ian_s]

could you put shims under the rocker shaft pedestals to lift it up a bit? i know the rover v8's sometimes need them but not sure about the 4 pots

[bm52]

maybe obvious but are you sure you got all the timing marks correct on reassembly, could be 1 tooth out?

[Phil Hancock]

The tappets that wont adjust out far enough to get a clearance check that the pushrods are properly in the seat on the follower, if they are not you will end up with the head off again while you change the followers as the pushrods will break the side out of the seating.

[Josh NZ]

Well, I sent off the rocker arms to be ground for extra clearance and because they were a little worn. Got them back and bolted everything back up, and one out of the three that wouldn't adjust, re adjusted properly and worked. Two (valves 6 and 7) still won't adjust so they will have to be done again.

Tried to start it and he turned over to my relief and ran on 3 cylinders plus responded well to throttle etc so there's some progress!

[Phil Hancock]

Rocker arms are case hardened so grinding the faces to get the clearance back should end up with the valve spindle tops wearing into the arm pads in use.

[Josh NZ]

What sort of time frame would that occur over?

[Snagger]

Not long, but if you can fit the valve stemn caps from a Tdi (they should have similar diametes, I think, but your wear issues may mean you don't have enough tappet clearance), then it'll help - they increase the contact area anyway, so reduce point loading, but are also sacrificial, so will be softer than the rocker pads and should take most of the punishment.

[Josh NZ]

Ok cool, I'll look into that, cheers for the heads up!

[Josh NZ]

Right, I finally got them all the adjust!

Fired up the motor and it ran beautifully, no smokey haze on startup like there was before the head went, rock solid idle and excellent throttle response.

Took him for a drive round to get the temp up, and as soon as it was warm, it slipped back to running on 3cylinders again! Is this due to us setting them when cold? It isn't overheating/smoking or anything, just running on 3.

I thought it might be due to the engine getting up to temp, it has thrown my adjustments out slightly.

[Josh NZ]

He runs!

The 3rd valve had frozen due to the pushrod coming unseated and not pushing on it. We simply reseated it, and checked to see if it could come off again, reset all the clearances and fired it up.

Then went all gung-ho and bought 4new spark plugs, air filter, engine oil and gearbox oil, and wired the stereo in as well! So very happy with todays outcome

[lexi]

Good for you mate. Keep your ear to the ground for some new or good second hand parts for top end.

Always better with spares.

[CwazyWabbit]

Brilliant Glad to see she lives once more