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Locking a dizzy


zep

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i betcha there is a jap engine out there that has a electronic dissy that will drop straight in leon have a ring around the importers and ask. like most of the imported 3/4 k toyotas all have elec dissys whereas nz versions dont. isuzu should have the same deal

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Guest Eddie W

A locked dizzie is to prevent detonation under high boost. Most electronic dizzies still have centrifugal advance so the problems still remain unless you get one that works with a computor.

We often ran locked dizzies or restricted the amount of advance on our supercharged engines. With a supercharger(and I assume a turbo is much the same) the fuel is mixed better and coupled with the extra compression on boost has a much quicker burn time and doesn't require the same amount of advance to get a proper burn.

I had a 1650 Cortina motor blown at 21lbs boost on 8.5 to one comp and didn't knock the advance back enough. Went like a rocket for two days and destroyed the block. I reduced the boost to 17lbs on 8 to one and locked the dizzie and it lasted for 3yrs and then it was blower probs that killed it not the motor itself. When it comes to advance on boosted motors I would advise erring on the side of caution.

Eddie

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Generally I'd agree with that but not on a 2L Pinto.. we found that the pinto loves more advance than usual, perhaps due to the poor head design. This goes for n/a and boosted. On my last dyno run we were consertaive with the advance on boost.. but couldn't make the power we were expecting so we upped the advance running 18psi and there were no signs whatsoever of detonation despite massive heat soak. Increasing the advance gave me a pretty much instant 40hp @ wheels.

I still run a locked diz though of course, since I'm running quite high boost I need complete control over the advance curve with the computer.

My mate ran low boost 6psi on a carby pinto and after trying lots of different cheap ignition setups, ended up finding the standard setup to work the best.. It seems pintos love boost and advance for some reason..

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Guest Eddie W

Hi Tek, Interesting that about the Pinto loving advance because as you say the more advance you need the poorer the combustion must be. Having computor control and anti-knock allows you to push the boundaries with advance but without them power tuning the advance on the dyno is pretty lethal. Most engines will produce more power at a setting that they won't tolerate on the track. The old Twincam Lotus motors would produce peak power at 38 degrees max and last half a dozen laps of Puke. At 36 degrees they dropped about 4HP and would last for several meetings.

The old BDAs were a good indication of head efficiency, needing only 30-32 degrees to get their best.

Eddie

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I think I have sorted my problem out, locating a double chamber boost retard diaphragm from a Cordia Turbo. Going to retro-fit this to my gemini dizzy and hope it works well.

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I'm running a max under load of 22+ a base of 6...or 8 ....i think it was

6 so that a total of 28 degrees of advance under full boost 20psi.

(Dizzy setting + ECU)

I reckon I could probably advance it further since I can't increase the boost anymore. I think lots of pinto users loose power because of an unwillingness to increase the advance beyond normal levels. Especially if you take a dyno tuners advice... it's just one of those things thats worth knowing.

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it totally depends on your defination of 'worked.' Typically, modified heads with raised compression will suck in more air so will require less ignition than a standard head. Say, going up 2 ratio's in compression bring the timing back 4 degrees.

Timing's a confusing subject at the best of times and I don't really know whats best suited for a n/a 2L especially when I don't know the details..

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Ok here's what you do. Crank up the advance until it detonates and then pull it back a bit.

'crank it until it talks' seriously that down right the easiest way of sorting it. Just be careful and when you here even the slightest ping back off, pull over and turn the dizzy back slightly and try again.

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Sweet as, cheers RT :)

Yea I wana run extractors, but they wont fit, like the steering and shit is all in the way...might have to get some custom made or something, or can you get different types of Cortina extractors that will fit straight on :?:

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dunno bro, I know that contina extractors couldn't fit on my capri cos the steering colum was in the way.. so perhaps 2L capri extractors would fit.

But you can definately get a set of new extractors to fit cos escort came out with 2L's.

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