PRE IGNITION FORD 250 crossflow

[TeddyXY71]

XDWAS250,
Seriously consider a permanent water injection set-up. That way it'll handle the slightly lower octane. Try and get a set-up that will produce the finest droplets/mist of water.

Pakz,
sounds like a good idea. I've also heard of a set-up that used a syringe inserted into the vacuum line to suck in a small constant bleed of water. The gauge of the syringe regulated how much could be drawn into the motor. Can't remember where I saw it on the net, as it was quite a few years ago.


Regards,

Teddy

 

[Anonymous]

hmmm i did try water injection manually i didnt really think it worked it was as soon as i have been running 100 octane... and ive gone back to that for now... If i run the vaccum line into my water resorvoir for my wipers do u think thats a start?

I have just also realised something else... since the motor was built cylinder number 3 from the front to the back of the motor in the engine bay has been having some trouble... the spark plug is coming out with all this shit on it... the rest of the spark plugs are fine... at first i thought it was excess carbon building up in that piston from the 600 holley... i have changed it twice with the 465 on and im still getting the problem.. Someone has suggested i put a warmer spark plug in. I have ive gone from a bp5es to a bp4es. I have been told this could be an oil control ring or it could even be the piston scuffing.

I have done a compression test on all pistons.. all come up with around 160. does anyone know the stock compression of each piston on a 250 crossflow?

Im going to let it go a bit with this spark plug and see what happens.. Does anyone else know what kind of problem this could be? and also relating to the water injection.. is that a good idea with the vaccum line in the water resorvoir of the wiper system?

 

[TeddyXY71]

The use of the dizzy vacuum line as a way of introducing water into the motor would probably only be for temporary use, no different than temporarily using a hose to piddle water into the carby.

But this bad cylinder sparkplug sounds like an interesting problem to follow up. Try cleaning up the sparkplug from the "bad" cylinder and put it back in and see if the problem disappears for a little. Or, clean the plug and then swap it with one of the good plugs. I'm not sure temperature range will have much effect here as I'd expect more than one plug to be having problems if the wrong temp range was used. Check you're getting good strong spark to the bad cylinder, it could be something as simple as a bung lead. See if you can sort this plug problem before going to any great expense on a water injection unit/kit. Its sound like this could be the root cause of a few of your troubles.

Regards,

Teddy

 

[addo]

Hey Teddy - you got me thinking. A worn down cam lobe might cause some sooting up while maintaining high compression readings.

 

[TeddyXY71]

Addo,
very true, but then how does one cam lobe wear more than the others?? But thinking ahead (as I'm prone to do ) your idea leads me to think that if the lobe doesn't allow the inlet valve to open to its full extent, you may not get good swirl and mixing of the fuel/air into the cylinder (not to mention short charging the cylinder), leading to erratic ignition behavior. Good mixing of the air/fuel charge is required for a clean burn after ignition. Bad mixing will also exaserbate the octane problems, especially in a high compression motor such as this. If the exhaust valve isn't opening fully then a build-up of carbon could well result, causing the problems. Maybe the cam lobe isn't worn, what if things like the rocker arms haven't been set to the correct tolerences?? Hey XDWAS250, it might be worth checking the operation of the rocker arms as you manually turn over the motor. (with rocker cover off of course) Check to see if each inlet and exhaust valve are going through the same amount of travel as each other during a full cycle of the motor (ie, 2 full revolutions of the motor)

Regards,

Teddy

 

[addo]

And for once, I wasn't setting you up! If you get a lifter that doesn't rotate in it's bore, that's usually where cam lobes start to degrade. A slower spinning pushrod or one that just "squirts" is often a sign of this condition.

 

[Anonymous]

hmmm, ive taken out the warmer spark plug ive put in and it seems to be ok.. a little richer... but i guess its the middle spark plug and with the redline manifold it distributes the petrol unevenly...

I will give it time to see how this spark plug reacts...

Could this be a pre ignition problem... Now with the 100 octane running i havent experienced any problems with the motor not wanting to turn off... And the spark plug is fine... ???? Maybe from it not wanting to switch off and running a while like that it creates all that soot..

Come to think of it everytime id switch it off the carby would blow out a cloud of white smoke... sometimes a little sometimes more...

 

[TeddyXY71]

Thanks Addo,
I learn something new every day. Didn't know about lifters causing this effect. Just goes to show how much a motor is really a complete system that requires everything to work properly, one thing out of kilter and the gremlins start appearing.

Regards,

Teddy

 

[addo]

I must have ESP. Read today in the paper that manufacturers are really investigating Urea injection after all!

But it's in diesel exhausts...

 

[Anonymous]

Have a look at the SPARK PLUG PROBLEM forum and have a look ar wat rnb said? What do you think?

 

[TeddyXY71]

I think rnb is certainly onto a good point. If the fuel distribution is out of whack for that cyclinder, it could cause your troubles. It gets back to my point in my post above about a motor being a whole system. If one part of the system ain't working properly, the whole motor will start to experience gremlins.

Teddy

 

[wagon]

Maybe there are 2 problems... 10.5:1 compression is pretty high, perhaps that is why it runs on etc. (so it needs the expensive fuel). What about mechanical problems as mentioned?? I think some analysis of the ignition system may point to the problem here... I know a bloke who specialises in whacky problems, I will harass him and make another posting.

BTW, E10 is great! It is cheaper than premium unleaded but has the same performance - and the motor runs leaner (15.1:1) with the O2 sensor running the motor in closed loop - and hydrocarbon emissions are way down too 50ppm.

Kendall.

 

[Anonymous]

Whats e10? and where and how can u get it?

 

[wagon]

E10 is 91 octane unleaded petrol with 10% ethanol - so it is 90%petrol and 10% ethanol. Here in Toowoomba it is the same price as ordinary 91 octane unleaded (although a couple of places sell it 2cents a litre cheaper than plain unleaded). It is widespread in Brisbane now too (mostly BP). I reckon it is equivalent to about 95 octane pulp (my motor has about 9.5:1 compression, and needs a better fuel than 91 octane to run well).

 

[Anonymous]

I understood what e10 was a little after i wrote ur reply.. sorry was a little slow yesterday.

I think its not enough octane though. i struggle with 98 octane with even an octane boost.

I wish theyd put e10 in a 95 octane petrol to boost up the octane a bit. Or even in the new Optimax premium 100 octane which only has 5% ethanol... to boost it up to 10% ethanol which would bring down the price.

Speaking about this ethanol, i had a look on the ethanol regulations in petrol and they recommend it shouldnt be used in carby engines.

Have a look at the www.fcai.com.au site and look under the ethanol section..

What do you guys think?

But when Super petrol was eliminated wernt they putting in ethanol? So why arent they recommending it now?