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Dizzy Problems on a 3.5 RV8 EFI


istruggle2gate11

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Hi all,

Posting a problem on behalf of a friend, Who needs dizzies, they are so yesterday

A friend has a 100" hybrid which used to have stromberg carbs and a points type dizzy. It came with all the usual problems / tinkering a old "worn out" system brings, so Ive converted him to EFI (flapper type).

The motor runs great with an obvious increase in power, however......

The dizzy has a habit of rubbing away the centre pin on the dizzy cap, I mean to a point of melting the plastic, what is causing this? It did this on two dizzies of unknown history.

Ive replaced the dizzy with a known history (off mine before megasquirt) and the same happened again, the caps are Genuine as is the rotor arm, the gear drive and oil pump connections is the same size / length / position as the original points type dizzy.

The only "grey" area in my mind is the front cover, it is off a Rover Car and has a remote oil filter fitted, is it possible the gears / pump house is that worn that it can push the dizzy up this far? I stripped the dizzy down, all seems well, including circlips in place etc.

Any ideas?

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Most likley a combo of Oil pump gear housing wear and cam/ dizzy gear wear ....

......and I would have said shaft wear in the dizzy adding up to excessive float upwards from the drive to the dizzy.

Nige

Dam...............

No, I dont like that answer, I wanted a reply of buy Service Item "Rotor Arm PRC5698" !

Hhmmm, has anybody ever tried shimming the gears?

The guy Ive done for, really is not a practical man, I will end up with the job of Correction, so probably full front cover strip down ahoy?

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Its an odd one.

Have been thinking some more

The Front cover / Ouil pump is Non Servicable, if the wear on the pump body is too great the casing is scrap

However, for the gears to wear this much the "Float" would be HUGE, it could only "Push Up" on the end of the dizzy shaft so much, to wear the centre terminal down thats prob not possible, and the Oil Pressure would be dreadful :) so I think I may have it wrong above :)

The dizzy you have changed, so thats out - as I HAVE seen shafts that have massive float....

I am now wondering if you have a mismatch of parts / quality / tolerances, ie A genuine / non genuine mis match, and tolerances too far out ?

How about fitting known good rotor arm cap both genuine ?

I have seen differing rotor arms in V8 dizzys over the years ?.... :unsure:

Nige

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Its an odd one.

I am now wondering if you have a mismatch of parts / quality / tolerances, ie A genuine / non genuine mis match, and tolerances too far out ?

How about fitting known good rotor arm cap both genuine ?

I have seen differing rotor arms in V8 dizzys over the years ?.... :unsure:

Nige

That was my initial thoughts, but its seen off a few set ups now, 3 dizzies have been tried, the last one fitted was known very good. 2 x el cheapo caps, 1 x halfords cap, 2 x genuine caps - only tried 2 x rotor arms though.

Sadly, any good known dizzy parts went in the bin months ago.

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That was my initial thoughts, but its seen off a few set ups now, 3 dizzies have been tried, the last one fitted was known very good. 2 x el cheapo caps, 1 x halfords cap, 2 x genuine caps - only tried 2 x rotor arms though.

Although it might be something more major I wouldn't eliminate the obvious - carp caps. I had one burn out the centre brush and in the second the brush just decided to up sticks and depart up it's own chuffer - it appeared that the spring had corroded to nothing (on a nearly new cap!) ... both purported to be genuine (that's what the boxes said). The third one was (and is, crossing oneself violently :) ) fine on the same dizzy.

AndyG

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There are two distibutor caps for V8 engines with corresponding rotor arms. The difference relates to the height of the cap and therefore how much clearance is between the top of the rotor arm and cap brush.

It might be that you have a low height cap with a high cap rotor arm - this would certainly place excessive pressure on the brush.

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