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[turkey]

ok folks - i am really struggling here - a cupie doll prize for anyone who can shed any light on this:

as per previous post - distributor cap on 33 twin carb 1.5 has severe gouges taken out from around inside of the cap. thought most likely cause was the small springs and counter weights being a bit loose and allowing too much movement with the counter weights scrubbing the inside of half the cap. also the rotor arm was scrapping on half of the top of the cap.

well i sourced another distributor - marelli single pick up sm802ax- slightly different counterweights and rotor arm from original on car but everything else looks same- has the vertical prong near the counter weights which i assume is the rev limiter. strange thing is it scrapes the inside of the cap as well.

so that's two different distributors - my initial thought is are there different distributor caps available for the different marelli models (single pick up vs dual pick up)? the shop i bought the new cap of said it should suit any marelli distributor for the 33 but i fail to see any other logical explanation? the cap can only fit one way - and is screwed securley into place and it must have been removed / refitted twenty odd times now without any change.

i noticed a post on the old board by "portugeezer" which mentioned something about a modification to a distributor cap but there was no other details and i have heard of cracked distributor caps before.

the cap i have here is a DODUCO brand (german) and the model number is possibly vk339 or 4644 and it says to fit 711 210 03/04.

also on the springs for the counter weights do the distributors usually each have one small tight spring and one fatter looser one? both these distributors have one of each spring on them so i assume this is normal and in fact the springs may be fine.

any ideas or clues in general would be mucho appreciated.

thanks-
david

[Admin]

Hi

I would expect the bearings in the distributor to need to be fairly badly worn to cause a problem like this. I cannot think of anything else that would have that much effect.

All the best

Keith

[rjbevan]

Hi, with regard to your query about the springs, they should be different as the advance curve is not constant. If I remember correctly there should be fast advance at low revs and then a slower rate, so to do this you need springs with different tensions.

I wouldn't have thought the weights could do the damage as there should be a stop to limit the amount of advance. Maybe the rotar arm assembly does this.

I would have thought it was the rotor arm. Have you changed this and does the one you have include a rev limiter? I think this is also spring controlled and is meant to move away from the centre electrode at high revs. But looking in the Haynes workshop manula for the Sud seems to suggest that the contact can only move a small distance. So in conclusion I suspect your rotor arm is not the correct one (or it's manufactured wrongly). The problem with after market parts (i.e. not OEM) is that they can be wrong.

Hope this helps and you get it sorted.

Richard

[Scott Sander]

Is your oil pump in good working order?

Maybe the shaft on your oil pump is bent. The oil pump drives the distributor. It is highly unlikely, but if we are looking at other possibilities that is one.
_________________
Scott Sander
'91 Alfa 33 Boxer 16V Monza - Awesome
http://www.sanderfamily.com

[turkey]

Keith, Richard, Scott- thanks for the replies. It would appear that the first distributor that was scraping the inside of the cap (from previous owner) was possibly the wrong type- it was a marelli sm802dx. the replacement distributor I have since sourced which matchs the workshop manual is a marelli sm802ax. don't know what the exact differences are but the rotor arm is different and includes a rev limiter and the counter weights are slightly different. So it turns out the only thing scraping on the new one was the rev limiter and after slightly bending it nothing scrapes.

unfortunately it hasn't transformed the car into a smooth high reving monster and it still struggles to go much over 4000rpm so i will have to keep looking for possible problems.

Thanks again
david