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Has anybody actually tried positive air pressure into a dizzy


mikec

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As above really looked into it, and although I find a few posts about it nothing that certainly says yay or nay, I'm about to try it by drilling into a dizzy cap just to see where exactly the air comes out and therefore where water can get in,

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You don't need to worry too much about water leaking into the distributor. If it were that easy you could just seal it up.

The moisture inside the distributor is condensation caused when the cold water contacts the warm distributor.

You can stop the condensation by having a flow of air through the distributor. One pipe in and one out. If you have a supply of compressed air on board you can use that. If not connect it to the inlet manifold and use vacuum.

To answer your original question, yes it works, I used the vacuum system on my V8.

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Most water in distributors is condensation, when it's warm and then gets a soaking it is chilled and condensation forms on the inside. When we built the mini special for the Weavers boxing day trial many years ago, all I did was put a bag over the cap and fill it with expanding foam to insulate it. I got soaked in freezing water driving said mini through the lake with water level over the bonnet, passing two V8s on the way. Yes it had a snorkel and high level exhaust too.

I would think if you can blow warm dry air into it you should get a similar effect.

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I nearly beleive exactly the same, except I think the water enters as high temperature steam from the manifold. And that it causes no harm at all until it condenses in the cap.

I drilled the body not the cap and connected it to a cheap compressor (£5) on a dash switch. Obviously the compressor needs to be in a dry place :)

There are two drain holes on the RV8 and many other distributors are probably the same. So i blocked one and ran a breather pipe to the other. Which is a lot more risky, as the spinning weights are in there. And this was an after-thought/improvement last year, the basic pressure idea working well for years.

I hear vacuum works well, but pressurising it slightly felt better?

12 volt fish pumps should be perfect but are apparently AC :(

Super heated steam can get in anywhere air can.

If you wade deep remember that the brake master cylinder has a vacuum-break valve when you loose the pedal. We think it will be around the rod area and can let water into the diaphram. It's a bit off topic, but it is a thing that you don't see mentioned.

But if all you want is to keep going with water been thrown around by the belt, then pressurising works well :i-m_so_happy:

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I think it is the rapid cooling Znd resulting condensation that causes it, maybe the answer is to insulate the dizzy. So when the water hits it condensation doesn't form? Not sure how to do that.

I have just done a quick test, albeit it in the dark outside, with a tube from a horn compressor rigged up to a pipe through the cap, it's only through the cap so I don't ruin the dizzy, turning it on a thought it'd be a few small bubbles coming out of the breather holes and round the cap maybe, and would be able to pinpoint these and see holes where it leaked, well it didn't happen like that, all I could see in the bucket were bubbles like a jacuzzi! Anyway next minute the dog disturbs the power lead and the pump turns off with the dizzy still in the water, so when I took it out there's water inside the dizzy. So I'll have to let it dry then try again, keeping the dog well away.

I may be wrong on this but is there not a chance of taking in some water using the vacuum method above?

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Condensation can only form if there is moisture in the gas (air) inside. If it is sealed after being in a warm dry environment condensation should not form. However if it can not be hermetically sealed ingress of moisture is impossible so adding a deliberate breather hole which a silica filter will make sure the air is dry.

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Yes I have tried this and lots of other things

Pressuring had some effect but not a lot

Its a combination also of HOW MUCH water, splashes etc - yes defo help, same with a sheild and or a rubber glovey thing

also good are the military RF shield covers for coil and Dizzy and then couple with shield etc makes better still

Decent leads are a must too, it all help for splashing etc

However, none will help if you are under bonnet deep in water and stionary, or if you hit water v hard as this just will kill a V8

The pressuring AND the military units AND decent leads AND then a sheild in front of the dizzy was the best I got before going Megajolt

and then squirt, but the above is a HUGE improvment on none at all

Hope this helps

Nige

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I used a silicon compound to seal the cap to body , and fitted two washer pipes one came from snorkle manifold ( it also had breathers from axles and transmissions) the other went to inlet manifold suction , The coil was enclosed in a sealed lexan box with a breather as well and ign amp was also enclosed in a sealed lexan box as well. I used magnecor leads (lpg spec) , the vehicle was totally reliable in fording creeks and travelling thru floods for considerable distances (KMs not yards) even hitting all the ign parts with a high pressure washer didnt affect it . JMHE

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I am not going to bother with the dizzy when the 3.9 goes into the next vehicle, while the engine is out its having a megajolt fitted, saw a chevvy small block running under water with MJ and am pretty much sold on it. plus points for me too being the mapping for LPG and petrol. Too many hours been spent under bonnet with this that and the other to keep moisture at bay and contactors clean for efficient running for a jaunt along some lanes or a little fording for the craick,right enough it is the steam vapour that does it after fording even if its only axle deep with a relatively warm axle case the steam comes up around the dizzy and has often caused slight issues the following morning when starting cold. Tried vaseline, the 9 finger chicken head thing which more resembled some random sex toy than an automotive part :blush: but hey it didn't work so going a little more radical this time

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