Stale petrol

[Dannyb]

Took the Spit for first drive since November. Wouldn't start until I used quick start. It had rough idle and when driven it misfired and backfired.

I drained the petrol and filled it up with fresh and it ran like a dream.

I worked out the petrol was 7 months old.

Never had this before but then its the longest I've not used the car.

Danny

 

[RobPearce]

One of our local Spitfire owners took his Mk3 out for the first time in three months recently and had similar trouble starting and poor running until it got some fresh fuel. Something's rotten in the state of Denmark modern petrol.

[Ben Hutchings]

Just a +1 on this, Mine was 6 months old. Just wouldn't start so drained and replaced. 

In the past 18 month old fuel was ok (not that it's a good idea!) 

[Bitumen Boy]

It's true that modern petrol doesn't keep, but I can recommend the Tetra Boost fuel additive as a preservative. In case you don't know it's tetraethyl lead (hope that's the right spelling, no time to check!) in a bottle so when added to modern petrol you get something close to the leaded petrol of old. I tried it after reading on another forum how there used to be various ethanol blended fuels on the market that didn't seem to cause the problems that modern ethanol fuel seems to cause, I figured that the lead may have been the difference. No connection to the firm but it's worked for me.

[Dannyb]

I drained off 20 litres and put it in my modern which had 3/4 tank so this filled it right up. Car runs OK and now down to half a tank so will fill up with fresh tomorrow. 

The spitfire now has full tank of fresh. Although I seem to have another problem. I wanted to check the timing but can't get the gun to fire on leads 1 & 2. 3&4 OK and also the lead from the coil. I have the clamp around the correct way, arrow to spark plug. Also getting good spark on all leads with an I line spark tester.  Don't make much sence.

Anyone else come across this? Also tried swapping out the leads.

Danny

[RobPearce]

You may well find the modern is happy with old petrol. It's the volatiles that evaporate off so what's left is thick and sludgy and doesn't "atomize" well. The modern has injection, which does the atomization under pressure through a carefully designed nozzle, so it will be far less sensitive to that than a carb.

The problem with your strobe suggests the spark is weak on the front two cylinders. This could be due to the plug gaps being wider on them, or the mixture being different, or the leads being resistive. It possibly indicates the ignition system would benefit from an overhaul and that might even improve the way it reacts to old fuel (after all, my GT6 seems OK on old fuel and the last time I drove my Spitfire it showed no sign that it was last filled up a year ago).

[Dannyb]

Sorted the timing light. When HT leads are touching it messes up the timing light. 

But I have a much bigger problem of misfire above 2,ooo revs. And the timing light shows it about 25 deg btdc.

On the 2018 rbrr the flywheel bolts come loose and the jarring recked the bottom sprocket and woodruff key and the slot in the crank. Although I repaired it with j b weld I believe the problem I had last September with the locked up brakes has broken the repair and the cam timing is out. I will comfirm this next week when I get time. 

If it has I'm thinking of drilling through the sprocket and crank and pinning it. 

Danny

 

[PeteStupps]

Quoted from Dannyb-

On the 2018 rbrr the flywheel bolts come loose and the jarring recked the bottom sprocket and woodruff key and the slot in the crank. Although I repaired it with j b weld I believe the problem I had last September with the locked up brakes has broken the repair and the cam timing is out. I will comfirm this next week when I get time. 

Ouch, that's a bugger. Adding insult to injury!

I've never used JB Weld but if the pulley / woodruff key gets the slightest bit of movement relative to the crank, it will take a hammering pretty quickly. I have read about MX5 owners using JB Weld on the keyway though, either the mk1 or 2 cars have a habit of ruining their keyslots apparently. 

[Dannyb]

Good news and bad news today. 

I checked the valve timing with valves 1&2 on the rock and found the tdc was 4 deg out.

Took the timing chain cover and the found the woodruff key and repair was OK.

Could the duplex chain have jumped the sprocket teeth when Tring to drive with locked up brakes?

Not taken the chain and sprockets yet to check all the teeth, although the ones I could see looked OK.

Danny

[PeteStupps]

Can't see how locked brakes would cause the timing chain to jump a tooth but I don't claim any expertise on the subject. I'd have thought a duplex chain would need some serious force from the cam or valve-train to make it jump. 

[PeteStupps]

Good news about the woodruff key though! 

Is it possible that your valve timing has been 4 degrees out since you repaired the crank nose?

[Dannyb]

Quoted from PeteStupps-

Good news about the woodruff key though! 

Is it possible that your valve timing has been 4 degrees out since you repaired the crank nose?

I remember taking my time double checking getting it all lined up. The car was running   very well since the spring of 2019. This seems to have started after the brakes seized and had to drive it to safety which must have put a terrible load on the engine.