http://go.mrgasket.com/pdf/37000A.pdf

Do you understand what the quys at Accel mean with the page 2 point 7 instruction on dwell setting.

I have a normal electrical meter with a pointer on scale 0-50. I connect the other lead to ground and the other lead to coils negative terminal.

How should I then set the dwell with my kind of meter? 26 degrees or 34-36 degrees?

 

Not sure what you mean by having a "normal electrical meter," but you need a dwell meter. I assume this is what you have... Disconnect the one set of points and set the dwell on the points that are still hooked up to 26 degrees on the 8-cylinder scale on the dwell meter. Hook up the second set and adjust the second set so you get 36 degrees total dwell. The positive (red) lead on the dwell meter goes to the negative side of the coil, and the negative lead (black) goes to ground. Just make sure that your distributor is also attached to the coil negative post.

 

Milloin thanks Lars - it is a multimeter capable of metering 7 different things (lowrpm, highrpm, ohms, points condition,...dwell...) so I think it is a normal dwell meter when I choose the Dwell function from the selector. Now I think I understand how to start the job...

One detail more Lars: "Hook up the second set and adjust the second set so you get 36 degrees total dwell." - Does this mean that I hook the second set (now both sets are hooked up) and I again start the engine and I only move the second sets screw to get the dwellmeter showing 36 degrees and then all is OK?

Would the result be the same if I would independently (allways the other set disconnected) adjust the both set to 26 degrees and after that hook them both and the meter would show 36 degrees - just curious?

 

BTW - it is worth checking the ingnition timing as well from time to time:

I have wondered (like 1,5 years - but luckily only 1000-1500miles) why I can´t get to low 12´s anymore and why doesnt the engine take more than 6000rpm (used to take 6500 easily) and this has happened gradually.

When I bought 2 weeks ago a timing light and surprize my max advance was 56 and idle advance was 26 - ARGH - no wonder.
I changed to 36max-6min and upper rpm was ok but on low rpm it stumbled and sometimes showed flames from carb and stopped...
So I asked advice and opened the distributor and narrowed the scale to
36 max and 16 min and it is like a new car - reacts and jump like animal.

At the same time I noticed that 3 of 4 carb mounting bolts are (and have been 2years) really loose (could tighted them by hand easily) - many symptoms dissapeared after having the nuts tight.

And I do not have vacuum canister at all.

So check you carb mounting nuts and ignition timing, time to time...

 

Vesa -
Yes, you are correct: you adjust the first set to 26, then hook up the second set and adjust that second set only so you get 36 degrees total dwell with both sets running. Yes, you can also adjust each set by itself to 26 with the opposite set disconnected, and this will give you 36 with both running. In fact, the way we used to adjust the dual point distributors back in the days of no quick disconnects was to put a piece of paper between the contact points on the one set of points to disable it, and adjust the other set to 26. Then remove the paper and install the paper on the opposite set and adjust the first set to 26. With the paper removed and both sets running, dwell would be 36.

You always want to check timing after adjusting dwell. Each degree change in dwell changes timing the same amount. As dwell increases (from the rubbing blocks wearing) timing retards.

Your 36/16 timing spec looks good. In fact, you can even shorten the curve a little more and bump the 16 initial up to around 18-20 initial for even better off-idle throttle response, but keep the 36 degree total spec.

 

good info

 

BIG thanks to you Lars! That piece of paper trick I will use next time!!! Eases much the job.

 

I will buy MSD distributor and replace the Accel dual poits one. Now I have 36-16 mechanical scale and will go to 36-20 as Lars advices but how much additional vacuum advance should I head for ? The initial 20 +? And is it better to hook up the vacuum line from the distributot to the carb frame (heard there is a port somewhere awailable in 850dp) or to the intake manifold?

 

Vesa -
With a quick advance curve that brings in 36 degrees total advance at about 2500 rpm, you need to install a vacuum advance control unit that does not pull in any more than an additional 16 degrees of advance. This will give you a combined maximum total advance at cruise of 52 degrees (36 mechanical/centrifugal plus 16 vacuum).

Whether to run your vacuum advance hose off the ported source or the manifold source depends on the tuning requirments of your engine and the amount of initial mechanical advance you're running. Run whichever source will produce the best quality idle (which is not neccessarily fastest idle). Generally, running off the manifold vacuum source will produce best idle and coolest engine operating temperatures. However, if you're running a lot of initial advance due to the cam/engine configuration, the engine will sometimes not respond well to another 16 degrees of advance pulled in at idle by the vacuum advance. If that's the case, try running ported vacuum.

All the Vettes out here in our group are running manifold vacuum for best results. Except my own car: I'm running 24 degrees initial advance with ported vacuum on the dstributor for best idle quality. Each car is different - you just have to play with the tuning to see what your engine combo needs.

 

Thanks again Lars - you put there out all info that I need to tune it properly now!