A few questions......

[free70]

Hi ;D

Ive spent the weekend working on my bug slowly stripping it. Going to be rebuidling the engine and sorting out lots of other bits - never done most of it before so got a few (!) questions and wondered if anyone had any ideas or can help....


1. Unleaded / Leaded: Ive got a 1500SP engine that has been running on leaded fuel. Been looking to convert to use unleaded but got confused.

The shops sell "unleaded conversion kits" (costing cost several hundred quid ) - new heads, cylinders etc - but Ive been reading on Volkszone and everyone reckons these packages are a con and you dont need to change your heads etc.

People seem to think a leaded engine should be fine without any changes to run on unleaded.

What ya reckon? Done it before? Appreciate some advice as its a biggy to get wrong.

2. Fuel Tank: As above, changing to unleaded and need to clean my petrol tank ready for unleaded - does it need cleaning internally with anything special?

3. Torsion arms - Im removing the front beam to allow a new clip to be welded in but im struggling to get to get the slotted nut of the torsion arms ends. Got the split pins out ok but the nut wont budge - being slotted is there any trick to get it off or is it simply stuck?

Thanks in advance

[Chris72]

I've been running leaded engines on unleaded for years without any problems

[theanimalbus]

We used to run unleaded and put this stuff in.........



But after rebuild i'm just running her on straight unleaded now, no worries

[free70]

thanks fellas

much appreciated.

will save a few quid

now all I have to do is strip it and rebuild it

thanks again

[free70]

Apr 17, 2009 12:56:05 GMT 1 @conna said:

;D to loosen ya nuts (on the van ) heat is the way .heat the nut up ,so it expands this works 99.9% of the time

thanks conna - will try a bit of heat on my nuts

[axenige]

right then

This has been all asked before so instead of a page of waffle about TEL etc.

You need to find out if the exhaust valves are harden to take unleaded if so no additives required to run your engine.

Remember that unleaded petrol burn far more quickly than leaded and thus burns at a much higher temperature, so make sure your that your getting good airflow around the pots

Finally don't use Super unleaded in your bus or beetle, this burns even hotter and can damage your engine

[free70]

Apr 17, 2009 22:20:44 GMT 1 @axenige said:

You need to find out if the exhaust valves are harden to take unleaded if so no additives required to run your engine.

Thanks Doktor

I am stripping the engine at the moment for a rebuild - do you know how I go about indentifying if I have the correct valves? Is it based on the cylinder head I have?

Any help appreciated

[fast65]

it will be the seats not the valves, but i have no idea how you tell the hardend ones but im sure most air cooled will run on unleaded with no probs

andy

[steve66!]

i was told that the seats are already hard enough to cope with unleaded.
I've run all my aircooled engines on straight unleaded and they worked fine!
S

[free70]

Thanks for the info steve66 and fast65 ;D

From what I've beeing told by various people, on here and elsewhere, it would seem unleaded petrol shouldnt be an issue.

Would be unlucky by the sounds of it if anything went wrong so just going to do it.

Thanks for the advice everyone

[axenige]

Apr 19, 2009 23:46:24 GMT 1 fast65 said:

it will be the seats not the valves, but i have no idea how you tell the hardened ones but I'm sure most air cooled will run on unleaded with no probs

andy

actually its both the exhaust valves and seats, both have to be designed to run without lead. If you've got soft valves with hardened inserts, the valves will burn. The same goes for using too high an octane rated fuel, remember the beetle engine was design at a time when the fuel was of a very poor quality and a octane rating well under the U.S spec of the time of 68 RON, which is why the compression ratio was low, Nazi fuel did not have tetraethyl lead added to it, this was not used much before the end of WW2, and modern 98-100 octane, is basically what the Spitfires Merlin engine ran on, the only difference being the fuel then had a hell of a lot of lead plus a special tin additive for good measure. Why? to stop the valves burning out

[steve66!]

^^^^^^^^Oh MATRON!!!^^^^^^^^^^^^^^^

[fast65]

Hi i hate arguing but

the leaded compounds present in the fuel provided the valve seats in the engine with a level of sustained protection. As unleaded petrol does not provide this protection, problems begin to arise due to what is known as ‘valve seat regression.’ This is where the valve seats of the cylinder head are slowly worn away, causing the valves to regress back too far into the cylinder head.

The valves need to lose heat extremely rapidly, and they normally do so via conduction with the cylinder head when they close. If they regress too much, there is less contact surface area between the valve face and the valve seat of the cylinder head and so the valves are unable lose heat fast enough. This can result in the valves becoming “burnt out” - literally having holes and indentations burnt out of them. This can cause considerable damage to the engine. Interestingly it is often possible to run unleaded petrol in an unconverted engine for short periods of time, as the valve seats have in the past already been protected by the lead that was present in the fuel. This is known as ‘lead memory.’ However, be aware that you if your valves have been replaced at some point in the past, and new valve seats have been cut for them, then this ‘lead memory’ may have been removed.

If you wish to run on unleaded petrol for sustained periods of time, then the best option is to have a machine shop perform an ‘unleaded conversion’ on your cylinder heads. This will normally involve them removing the old valve seats and replacing them with special hardened alloy valve seat inserts – which tough enough not to suffer from valve seat regression. It should however be noted that, due to a change in octane number, when converting to an unleaded fuel, your engine’s timing will need adjusting. This is quite important as otherwise detonation can occur instead of a controlled combustion of the fuel and air mixture in the combustion chamber. Detonation, sometimes called ‘pinking’ due to the sound it makes, can literally ruin an engine.

But as i said air cooled vws have hardened seats ;D running higher RON fuel is not normally a problem as your AFR is better so cooler , if you run a lower RON this is were you can get problems with valves and pistons melting but only normally in turbo charged cars or FI engines but most of those will run a closed loop system with a wideband controller on. This is why jap imports engines some times melt as they run 100 RON in japan, they export all tuned up and the boy racers run them at full boost on 98 RON and there AFR is too low, temps get too high and normally they blow a hole in a piston any how see you at big bang ;D


andy

[rick]

not sure if its the same situation exactly but my mates mini is leaded and he has run it for ages on unleaded with no probs .