So with search being down still I havent found much on this outside of guys running Bridgey set ups.

So here's the facts:
1984 RX7 GS, S4 N/a 13b, Dellorto DHLA48 side drafted 250 main jets 80 idle, stock ports, MSD blaster 2 coils, new wires, new plugs. NO VAC ADVANCE

My timing is set as such

Which is the stock timing according to my pulley and timing light. However I am probably going to locate TDC just to be sure its right

Seems to idle decent but loves to misfire if holding a constant RPM of say 3200RPM, more or less as the dizzy advances mechanically. This is under light throttle conditions.

Then theres the tune. The car doesn't want to idle smoothly at anything less than 8.0 AFR on my wideband, which really doesnt seem right to me. However, at WOT the AFRs are right around 12, which is about where I wanna be.

So more or less, my puerto rican buddy who is of course a rotary nut, said I should advance my timing. I gave it a shot and ran a few tests. It idled like a pile. VERY lumpy and misfired quite a bit. However the motor would idle at a much leaner mixture, but still be missing. I took it around the block a couple times, and it seemed to run about the same.

So I guess my question is that what exactly should I be getting from advancing my timing?

/ramble

 

Your engine is normally aspirated correct?

Connect the vacuum advance.

There is no reason to not take advantage of it.

 

I never did figure out why they said to remove it in the racingbeat instructions

 

i think your stumble is in the carb, and not the timing, however finding TDC isn't a bad idea.

so once you have TDC, and you figure out which distributor you have then playing with the timing will probably gain something.

i don't know the Dells, but on the weber, the idle speed screw is mislabeled, and it should just be called the throttle stop, the carb is supposed to be idling on the idle hole which is a PLACE. i think most rotary weber people are running on the 1st transition hole. this makes the idle mixture screw ineffective, and the mixture is mostly determined by the idle jet. then they get a lean stumble because there is only one more transition hole (which is a PLACE, throttle plate relative to the hole in the side of the barrel), until its running on the main circuit which is airflow based. i think the Dell has 3 instead of two

also i would try tuning idle on each rotor separately, its possible there is an air leak or some other weirdness going on

 

Yeah im planning on doing the rear rotor apex seal method for tdc.

The idle speed screw is pretty much the same, just sets where the throttle plates stop. My mixture screws do still work, but as I lean the mixture out, it will begin to idle rough when the mixture is reasonable, ie 12 to 13. Are you saying this could be a result of the Transition circuit not functioning properly? I can see in the afr's when the main jets kick over.

 

No correct manifold vacuum source on the dell or built into the intake. You can hook
vacuum up on the advance using manifold vacuum, it will just be fully advanced at
idle until you take off. Still helps. I've run it both ways.

 

This.

Make sure you have all the basics right like fuel pressure, idle bleeds adjusted, AP
adjusted etc. See www.gruntled.com for details.

 

You don't want to advance your timing....you want to retard it. Somewhere in the neighborhood of 24* btdc with a 10* split @4000rpm if I remember right for a 13b

 

I know dells very well. are your low speed jet holders drilled? go to the gruntled site and read about my jetting under the 6 port set up by joe chapman it is great. also i do not run any vacuum to my dist. and it made 168 on the dyno(corrected hp) not rear wheel. do the mods suggested by me and racing beat you will be very happy with the results. The accelerator pump mod is very important to make off idle good and air corrector on the main really helps on transition from low to main good. also remember the dell does not transition to the main jet until around 3500 rpm. i got a 11.5 ar at idle and a 10.2 at wot with this and still get 15 mpg average.

pm me if you have questions

Joe C