triple forties and distributor setup

[smokie]

Hi, I found this article when trawling the net and have a couple of questions :

1. is it really necessary ?
2. I've stripped my distributor but the "fix" is way beyond me, is there anyone i can send it to to have the work done.

Thanks .....

“Weber DCOE triples need a specific advance curve to compensate for the increase in air/fuel flow they provide. They do not need the vacuum advance, in fact the manifold vacuum levels can/will drop considerably using DCOEs and the vacuum advance will become very ineffective. Simply don't use it.”

Triples like a lot of initial advance to run properly. This means instead of running 8BTDC at idle you should be running about 16-18BTDC or the engine will chug and you may get some popping out of the carbs. But just unplugging the vacuum dashpot and bumping the timing up isn’t the way to go either. If you increase the idle timing into the mid-teens using a stock Z distributor you can easily push full advance into the upper 30s/low 40s which results in detonation.

THE MOD: What you do is have a reputable distributor shop shorten the advance-weight range in your distributor so you can set it at 16BTDC at idle but still max out at around 34 degrees maximum. The rebuilder measures the advance and partially welds shut the slots (epoxy or similar materials are too soft). The top advance plate is then locked in place, the vacuum dashpot removed and the hole plugged. The result is a full mechanical distributor with the correct curve and modified advance range for Webers.

 

[morbias]

Welding the end of the slot should be pretty easy, don't think you need to take it to a 'reputable distributor shop' (whatever that is). It would take a bit of trial and error to get it right though.

But I don't think there's any need to lock the advance plate, surely leaving the vacuum dashpot on the distributor body would keep it in position as the return spring on the dashpot is pretty strong and would hold it there.

 

[smokie]

I guess this is pretty much beyond me. I'm not too far away from the bloke that looks after willie robertsons track Z so i'll probably wait till i have the car up and running and get him to do the final setup. I've had cars at him before having webers set up correctly so hopefully he will know what to do ??? Thanks for your reply.

 

[jonbills]

I did it on mine. Pretty easy. Didn't weld though, just put a gob of plastic metal type stuff on the advance slot to shorten it, then filed it down a bit to get the idle a full advance right.

 

[morbias]

Out of interest, did you do both slots? I need to do this on mine too - also which distributor are you using? I think I started a thread on this a while ago, mine has one advance spring - I have a few other springs laying about so not sure if it might be worth the time and effort experimenting with them.

 

[smokie]

which slot needs welded up ?

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[morbias]

yellow and/or red I think - basically you want to stop the weights travelling all the way out.

 

[smokie]

i notice that the yellow and red are different sizes ?????

 

[morbias]

I have no idea then!

 

[jonbills]

I'm using the standard 260z distributor. I'll get the model number off it if you need it.
I only adjusted the travel on one slot. From memory, it was about 3 or 4 mm of travel I removed.

I only had one spring in mine too. In fact, I've had several distributors, and all had one spring. I tried putting a 2nd spring in one and it didn't go so well, so I concluded they're meant to have one spring.

The thought did occur to me that perhaps one spring/two spring is the difference between European and US distributors.

 

[morbias]

Thanks for the reply, I imagine we both probably have the same distributor then. I thought maybe if I put another spring with the correct rate on it I wouldn't have to weld it, or would that be too easy

 

[jonbills]

I checked and I have D609-56A. could have come from an L24 or L26.
The springs don't control what the max mechanical advance is - they just control how fast it gets to max advance. 1 spring gets there faster of course, say 3500 rpm, whereas 2 springs it might be 4000rpm when it hits peak advance.
I reckon its the rounded outer end of the slot by the yellow arrow you fill in by a few mm.

 

[smokie]

Brilliant, thanks for your help.

 

[morbias]

I checked and I have D609-56A. could have come from an L24 or L26.
The springs don't control what the max mechanical advance is - they just control how fast it gets to max advance. 1 spring gets there faster of course, say 3500 rpm, whereas 2 springs it might be 4000rpm when it hits peak advance.

Good point, and thanks for checking,. it's the same distributor I have so I should be ok without recurving it