ultimatejay

iTrader: (1)

Vacuum advance are for stock city driving habits. This is a race car just leave them off.
Where do you have your mixture screws set at?
Screw both of them all the way in and them turn them out 1-1.5 turns out. That will be a good starting point. But your float level is very critical so do what I told you and check for any fuel dripping in the Venturi while the engine is off. You can also check by turning just the fuel pump on with engine off and look down the carb. There should be no fuel dripping down anywhere inside the carb. If there is then like I said before your fuel pressure is too high or your float level is too high or both.

Shrimp

No MSD, stock ignition.

The float level should be correct, I set it to within .03mm. Spec is 12-12.5mm from top of float to the main cover.



I set it to 12.28 according to my digital caliper. The float must be resting on the needle valve but not compressing the spring (which would block the flow of fuel).

Now setting the pilot screw, according to Mikuni it should be set to 1 1/8 turns from seated position. The "seated position" is the pilot screw screwed all the way in, right? Then you back it off 1 1/8 turns. Done that. According to them, if you need to turn the pilot screw more than 1/8 turn from that it's jetted wrong.

I will fiddle with the pilot screw just to see if it helps as well as check the timing and see if anything comes of that.

From what I have seen of the inside of the carb there is no fuel coming out unless I work the throttle and then it's coming out the pump nozzle. Unless the car is running in the upper RPM, then it's coming out the venturi.

I am no expert but I am pretty damn sure I have this carb setup properly other than maybe jetting but even then, it should at least idle with the recommended jets.

ultimatejay

iTrader: (1)

If all that checks out and your timing checks out then you need to adjust the mixture screws. Try turning them in a half turn and so forth and see if it gets better. You may have to turn them out some more. I don't know about Mikuni but on Webers when you turn the mixture screws in(clockwise) it leans out the mixture and vise versa. Rotaries like to idle on the rich side. So try that next

Shrimp

Same for mikuni, turn them in and it clogs the hole leaning the mixture. Too rainy outside to work as my garage is open so gonna have to try tomorrow.

Shrimp

Progress!!

I unscrewed the pilot screws both 2 full turns (made it richer) and voila, this biatch idles. So my pilot screws are either buggered or f the mikuni manual of 1 1/8 turns. Either that or I need some seriously rich pilot jets.

Going to check it though by re-gasketing the exhaust and tuning it according to the AFR. I don't have my tach hooked up so I can't tell the RPM it's idling at but at least it is.

ultimatejay

iTrader: (1)

Your welcome.... Told you rotaries like to run rich
Now you want to keep turning them out or in until you retain the highest idle possible or highest vacuum reading. And then adjust your idle screw to whatever idle you like.

Shrimp

As I have it set right now AFR is reading 14.3-14.6 at idle.

ultimatejay

iTrader: (1)

That's on the lean side, drive the car and see how it drives, you may have to richen the idle mixture some more or go to a bigger pilot. Remember the main fuel jet will effect the idle circuit as well.

Shrimp

What AFR number am I looking to hit?

Looking for some more info on the ACV port on the motor and maybe needing to fill it.

The intake manifold for the Mikuni comes with two o-rings to seal the coolant passages on the motor. The intake manifold doesn't have any channels for the coolant, it just blocks them off. Same for the ACV port. It just blocks it off.

Do I still need to fill the ACV port since there is no way for it to flow through the manifold? The manifold doesn't seem to get hot when running but rather from heatsoak if you turn the engine off when hot and let it sit.

Also had another breakthrough. I went to adjust the stop bolt on the gas pedal and noticed the pedal was hanging up way before hitting the original position of the stop bolt. Thinking WTF I went and played with the throttle shaft and sure enough the nut that holds the throttle cable holder was hitting the intake manifold. It wasn't allowing the butterfly to go full WOT. There are two bolt holes and it was mounted in the closer one so I moved it to the further one and now it lines up the butterflies perfectly. I don't know if this was meant as the original throttle stop but I don't think it was so I am going to fashion something up but in the mean time I have the bolt on the gas pedal and the nut hitting the manifold and it lines up so I'll roll with it.

I took it for a spin afterwards.

This thing is a beast compared to the Nikki now that the accel pump works.

ultimatejay

iTrader: (1)

The aftermarket manifolds do not have ports for coolant passages or acv port. So what you can do is install freeze plugs in the coolant ports in the rotor housings- these-
http://www.mazdatrix.com/b1.htm
This will allow you to remove the intake manifold any time you want and not spill any coolant. Make sure you use an intake gasket that covers the acv port or it will leak exhaust.

Jeff20B

iTrader: (13)

Why not suggest filling the ACV port with quicksteel or devcon? Why not? The intake is off. Possibly less heat will get to the manifold this way? A cooler intake manifold makes more power? Maybe?

Shrimp

Well my concern is whether or not I need to take the motor apart to fill it with quicksteel without it getting too far in there.

Jeff20B

iTrader: (13)

There is a lot of info on the forum indicating that you don't have to tear down the engine to fill the ACV port with quicksteel. Simply clean the port. Then fill with quicksteel. Couldn't be easier.

Shrimp

I am trying to figure out where the acv port opens up to on the inside.



Is that the opening?

Jeff20B

iTrader: (13)

Do this.

j9fd3s

iTrader: (3)

flow thru the passage is like this pic. in a stock car air pump air goes thru there to the exhaust ports. when you block it off, there is no flow, so the exhaust gases just become an insulator.

Shrimp

Ok, so there is a lot of room in there to jam the quicksilver in before it comes out anywhere that would affect anything.

Since there is no flow though, shouldn't there be VERY little heat transferred? Air is a terrible conductor and it's not flowing through the acv port but rather just sitting there so how much heat could it be putting into the manifold?

Or is the air see-sawing back and forth as one rotor exhausts and the other is not so some flow goes through the ACV port and out the other exhaust port? I theorize this because doesn't the ACV port connect the two exhaust ports?

j9fd3s

iTrader: (3)

it does connect both ports, but then it goes up a long dead end passage.

i'm sure there is some heat there, unblocked, but i don't think its very hot, and its not a big deal in the scheme of things

Shrimp

That's what I am thinking as well. Can't be transferring that much heat to the manifold if it's just sitting there and at this point it seems like the benefits won't outweigh even the small amount of work it takes.

Jeff20B

iTrader: (13)

I've had manifolds that were quite hot to the touch on an idling engine until I added some quicksteel to the ACV port. After that they were just kinda warm. It's worth it in my opinion.

ultimatejay

iTrader: (1)

The manifold already blocks this port off, no need to fill it up with epoxy, etc. just a waste of time. I don't see how it is going to effect the heat much either way. Just make a heat shield between the header and intake and call it a day.

Shrimp

Well the manifold I am using stays cool. Yes, cool (not warm at all) to the touch except the VERY bottom of the manifold where it connects to the engine.

Jeff20B

iTrader: (13)

I've given you my opinion and others have given you theirs. Do what makes sense to you.

j9fd3s

iTrader: (3)

yep exactly. both ways work

mustanghammer

iTrader: (3)

On my IT car (12A) I just stuffed the port with aluminum foil, packed it tight and the finshed it off with JB Weld. Always did it while the engine was assembled. Don't have an A/B comparison but in my mind blocking off a heat source from the intake is worth it.