Back in the days of the GM HEI distributors we used to get a quicker advance out of the distributor by putting lighter advance weights and more importantly lighter advance weight springs in it. Has anyone tried it on the Hitachi's in these cars? If so what did you use and what results did you get.

 

Also, is it possible to use an adjustable vacuum advance on these? Again, if so what did you use and what results were gotten?

Of course that could all be done, but the parts/knowledge to do so is not something you'll find here I'm afraid. Perhaps talk with a distributor shop, or check the nissan communities as they used similar Hitachi and ND distributors.

 

GD

Of course that could all be done, but the parts/knowledge to do so is not something you'll find here I'm afraid.

 

The GM's weren't all the tough. Looking at the exploded diagram of the Hitachi it looks like the springs can be done without the need to pull the disty. Off with the rotor. Two screws come out which allows you to lift out the pickup coil, stator, magnet and advance plate.

 

It's just a matter of finding the right tension springs and size weights to put in. Too light and advance comes in way too quick, and the car will ping like crazy. Too much so to compensate with timing adjustment.

 

I'll pull one apart on the bench and see how it goes. Stay tuned.

I remeber a post about someone having the disty recurved. They said the shop mentioned how similar it was to the toyota disty. Do a search here for the info.

Also, it would be best to have it done by a disty pro.

a friend that is in the USMB told me that changing the original ea82 vacuum advance with two tubes from the disty, with a ea81 vacuum that has only one tube, it makes faster advance. he said 2wd models has faster advance than 4wd.

You should change the title of this post to

 

*Hitachi DISTRIBUTOR question*

 

Many models got hitachi carbs but denso distys.

 

 

With that said, I suppose you could use lighter springs and/or heavier weights for a quicker advance. I doubt you'll find anything made for this purpose. Probably have to weld some nuts to the weights. Springs from another type of disty could very well work too.

 

As far as the vacuum advance, I don't know of any way to adjust that.

a friend that is in the USMB told me that changing the original ea82 vacuum advance with two tubes from the disty, with a ea81 vacuum that has only one tube, it makes faster advance. he said 2wd models has faster advance than 4wd.

 

Only 2wd *feedback* carb equiped models had 2 vac ports. The first is a sub advnce controlled via solenoid by the ECU. The second is a pure engine vacuum advance.

 

Since only the 2wds had that disty, how could you change that to a 2wd disty?

he said 2wd models has faster advance than 4wd.

 

That is not correct. The curves are identical between the two.

 

GD

Back in the days of the GM HEI distributors we used to get a quicker advance out of the distributor by putting lighter advance weights and more importantly lighter advance weight springs in it. Has anyone tried it on the Hitachi's in these cars? If so what did you use and what results did you get.

 

Also, is it possible to use an adjustable vacuum advance on these? Again, if so what did you use and what results were gotten?

Try Philbin Manufacturing in Portland; they rebuild distys and replace torn diaphragms in your vac advance unit (NO one has any new stock on these any more). If you can't find Philbin by searching old posts, I'm sure GD has their information.

Found it: http://www.philbingroup.com/

You should change the title of this post to

 

*Hitachi DISTRIBUTOR question*

 

Many models got hitachi carbs but denso distys.

 

 

With that said, I suppose you could use lighter springs and/or heavier weights for a quicker advance. I doubt you'll find anything made for this purpose. Probably have to weld some nuts to the weights. Springs from another type of disty could very well work too.

 

As far as the vacuum advance, I don't know of any way to adjust that.

 

Heavier weights would make more sense on the surface, but the aftermarket HEI weights actually were lighter. They also had a steeper ramp which gave a greater timing advance for a given amount of movement, yet they also had less centrifugal advance movement built in. This allowed you to set your base timing higher without getting too much total timing, and the ramp up to full advance happened quicker. Much better off-the-line performance was the result.

 

I sure miss the days when you could tinker with stuff like that... cheaply. Now you need a laptop with tuner software, a wideband O2, and cable interface. In otherwords, not cheap!

Heavier weights would make more sense on the surface, but the aftermarket HEI weights actually were lighter. They also had a steeper ramp which gave a greater timing advance for a given amount of movement, yet they also had less centrifugal advance movement built in. This allowed you to set your base timing higher without getting too much total timing, and the ramp up to full advance happened quicker. Much better off-the-line performance was the result.

 

I sure miss the days when you could tinker with stuff like that... cheaply. Now you need a laptop with tuner software, a wideband O2, and cable interface. In otherwords, not cheap!

 

RIGHT!!!