Any ideas?

[LFW]

Central inlet cam cap bolts found loose less than 500 miles after complete professional engine rebuild.

The lower one came out with ease. The other stuck rotating in helicoil. With good advice from engine builder managed to get the stubborn one out and replaced with 2 new helicoils and correct bolts. Valve clearances returned to normal settings. Problem reoccurred not long after. Engine returned to builder. He said inlet cam bent and carriers a mess.

How does a cam bend?

When engine purchased (on builder's recommendation) an inspection found several valve springs broken. New valves and springs were fitted in rebuild. Cams were said to be of an odd profile, worn but useable.

Things have become very expensive!

[P. de R. Leclercq]

Probably, the "professional" didn't use the correct caps, or fitted them in the wrong places.

Alternatively the camshaft might have been bent already, but the "professional" should have spotted this - it would be difficult or impossible to turn.

No comment on valve springs: I have never in 25 years of Fulvias seen a broken one.
Best of luck

Paul

[LFW]

[P. de R. Leclercq]

It is much better to replace the Helicoils with Timeserts - they screw into the same thread as the Helicoil (if it's still there) and are stronger and more reliable.

Paul

[Huib]

Very strange. A wild idea: check if the inlet and outlet rocker shafts weren't swapped. They differ slightly in length. A stalinistic engine rebuilder might be able to get bolts in even after mounting them in the wrong position.

As Pauls says, a bent camshaft is unlikely. It would not have been possible to turn it. I am trying to think of something that might connect a bent camshaft and the broken valve springs (which is also curious).

It is vital that bolts of the correct length are used. I have the sizes in my workshop where there is no computer. Here at home I don't have the sizes. From the top of my head: M8x65 though the holes which are doweled. M8x60 for the longer holes without the dowels. And M8x40 of M8x45 for the short holes. I think M8x40 but you can compare the length of the part that sticks out of the cap with the M8x65 bolt. The bolts in the holes with the dowels are just a bit longer because the helicoils are below the dowels and thus a bit further down.

As Paul points out the aluminium often goes bad and the helicoils come out or at least they turn. Best replace them by inserts as Paul points out. An accurate job. Best take the head off. After having had to take the same head off five times or so some engines ago I now assemble heads completely before putting them on the engine. The book says they have to be torqued to 2,5kgm. Take this seriously. Don't be sloppy. The torque wrench should click sharply. If you are even half in doubt, remove the helicoils en put in inserts.

Another possible cause may be that the rocker cover bolts pulled up the caps. If the helicoils / inserts are ok and if the correct bolts (and washers) were used and if the bolts were properly torqued this should be impossible. Bolts should be grade 8.8 or better. Remember that the counter force for opening the valves goes to these bolts which adds to the pulling force from the cover bolts.

The cam shaft bearings are bored in line. The center caps are identical. It is possible to mount them in the wrong position which may ruin the line bore.

[ecoangel]

The rocker cover bolts were always hand tightened with an allen key. The one that mounted into this cam cap was always coming loose. The first one was a new bolt as supplied by the reconditioner. He said it was normal for these to come loose. So I just hand tightened them after every road trip.

However I noticed that oil kept coming out of this one (pouring into the No3 sparkplug hole area) and after one trip realised the rocker bolt was completely loose - in fact sheared. This was why I removed the cover to take the sheared piece out - it came out extremely easily with a finger nail!

But that's when we saw the cam cap bolts in this photographed condition.

After the helicoil repair the same position cam cap bolt kept coming loose and one even fell out on the road somewhere!

That's when we chose to return the engine to the builder.

He stripped it down and said inlet cam was bent and that several of the cam cap bolts were too long (they were fitted by his workshop). Also some strange damage/discolouration to the No3 Inlet valve.

My theory is that as the cam cap lifted the no3 inlet valve/guide stem became trapped/encountered extra friction from mis-alignment of the cam cap. If the cam was bent from the beginning (maybe just in the middle) then this would explain the lift of the middle cap.

I don't see how the rocker cover bolts could lift the cap if the original bolts were properly inserted ( 2 M8s against 1 hand tight rocker bolt).

So the cam must be the major reason.

Fulvia cams being short it may not have been obvious to the builder on initial assembly. Or do you think assembly may have been rushed and caused the bending when the engine was started up?

During the helicoil replacement the cam was fastened in situ and not removed.

[ecoangel]

"After the helicoil repair the same position cam cap bolt kept coming loose and one even fell out on the road somewhere!"

Sorry I meant that particular ROCKER cover bolt kept coming loose and one did indeed fall out during driving!

[tim]

Just to follow on this thread, I thought I ought to check the rocker shaft cap bolts prior to checking the valve clearances on my 1600 HF.

This was after around 6000 miles of hard motoring (2 Goodwood track days, Prescot Hill climb, thrash to-aroung and back from Turin, and 2 Cotswolds Rallies).

Guess what. two of the lower shaft cap bolts were loose as there threads had failed. One was a helicoil repair that failed and the other was a timesert. Bothe I think due to slightly shorter bolts being fitted -- but will establish when /if I can repair in situ.

Keeping my fingers crossed.

Tim

Anyone got a spare 1600 head?? (Please email me).

[LFW]

Have you checked the length of the bolts?

Take it by lower you mean exhaust cam?

Was it in the middle or one of the end caps?

I have heard good reports from another 1600 HF owner that Coberg Engineering do better inserts than Helicoil.