Low power and bangs backfiring

[Max911]

Dear all

Unfortunately ending my Dolomiti run... Before getting home

Suddenly my 2,2 T my 70 loose power and start hardly backfiring from cylinder 6...

Initially changing noise and rpm when idling without spark then no more but squitting at idle and banging if accelerating...

Waiting now for trailing rescue...

I m not able to post video via tapatalk...


Any suggestion? Valves blocked?

I'm scared...


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[KS]

Start by checking the points in the distributor before you start panicking too much.

[impmad2000]

2.2t, running Zeniths ?
Check for pipes popped off the carb body. Simply put them back on and read Gary71’s article on the Zenith carbs and what to do with this circuit.

[Max911]

Thanks for your suggestion but I understood that was something harder... Probably related to valves

Before getting up on tow truck I noticed an oil leak... Not so small...(picture)...

Only with engine running so I suspect rocker arm axle out of his site...this would explain problem on valves and oil leak...

Now the question is "why rocker arm axle loose tightening and goes out of his site"?
All bolt checked less than 1000km ago during a valve clearance check...



Thanks for any suggestion


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[hot66]

I had a rocker arm 'walk' a few years ago. massive oil leak and cloud of smoke. Reckon it moved due to heat and expansion as it was the year of the hottest CLM ever

Even after repair, we checked and it had moved slightly again. During the full engine rebuild we fitted rocker lockers rsr style that prevent the rocker shafts from moving

[Max911]

Thanks hot66!

I know rocker axle rsr style (they have an oring site for preventing leaks) but not lockers... Have you please got a part number to search for them? Thanks


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[hot66]

from memory it was these

https://parts.turbokraft.com/collection ... t-lock-set

[Max911]

Thank you very much!

Surprisingly not so common and known as improving kit


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[Max911]

Dear all

Update: as suspected rocker shaft walk away... Cylinder 6, exhaust valve...

Fast...definitive... Please see following pictures



All refixed... Engine runs as good as before, no oil leak...maybe just a little bit from rocker axle shaft

Now I'm going to order the upgrade kit as suggested by hot66 plus rsr oring to prevent further walk away...

This time I've been lucky not to loose oil on the street o spitting engine piece destroying everything... I dont' want to risk anymore

I'm wondering to get the engine out... to struggle not too much for the entire job and to take profit to change flywheel seal and checking here and there...

I've done 1500km from getting car on the road and registered and enjoying it very much.... Unfortunately the real first long trip of the last weekend ended with the rocker shaft trouble

Probably the 35 degrees of the italian summer, highway cruising and then 3 Dolomiti passes had been the tough trial I expected to check the car



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[Max911]

Rocker shaft locker set just ordered from Turbokraft... Expensive but I hope to have bought peace of mind in terms of no more rocker shaft walk away...
I will post some pictures during installation and although not required I think I will go with an engine out to get best access and take advantage to set a minor oil leak from flywheel seal and further checks...


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[Max911]

Dear all

During holidays I went through an "engine out" to install the rocker shaft locker kit (although not mandatory... According to Turbokraft)

But after 2000 miles since car back on the road following restoration I took advantage for an overhaul of some oil leaks and install rocker shaft locker kit with the engine on a comfortable stand...partially helping 35 celsius degrees in my garage...

Following some pictures


Comparison locker kit vs standard rocker shaft nut



Some
Couples are marked A-a and others B-b... They have disposal mounting order... Clearly set on instruction... That turbokraft DON'T send me with the kit...but they quick replied to my mail...



All valves clearance rechecked, all end-float rockers checked (all in the middle of values min-max...the closest is the six cylinder exhaust side that was that walked away but still within manual value!!)

Leakage test done... All good values... "Hsss" perceived a little from crankase ventilation system...so from piston rings that have I suppose all the 87.000miles showed by the speedo gauge



Now finally engine back in car, road tested, carburettor newly set, now waiting for final fine tuning but I'm satisfied...

Some minor oil drop persists (along case junction...never splitted) from oil seal ring seems ok(all new and mounted using "curil T" sealant)... Maybe some drops from engine cover...still the original hand sanded and mounted without chemical helps...only
Gaskets

Now time to enjoy the drive hopefully for long

Thanks for your attention
Max


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[911hillclimber]

That was a good little thread!
I've never seen those rocker shaft locks before, but I've never had the shafts move after a re-build, but I've only done 4 rebuilds...

The rocker cover gaskets with the silicon sealing ribs on the gaskets are very good (lower covers).
I've learnt something today, so thank you and to James!

Happy driving.