Triple Mikuni thread

[madkaw]

Well some of you that I am now proceeding with my Mikuni install.When I purchased these carbs I got lucky and recieved a very complete kit. These look new right out of the box-infact the carbs came in a Mikuni box:) I even recieved an original 1985 catalog and service manual.

I decided to post up parts of these Mikuni publications on here for all to view. Between the two publications I have part numbers and illustrations of the carbs and their parts. Let me know if there is anything in particular that you might want to see. I know folks buy these carbs with the intent to rebuild, but not much to go on. I hope this thread and pics will help.

I'll start out with the some stuff from the catalog

[spitz17]

This is AWESOME! Would it be possible to make a PDF of the booklet and post it? Especially the tuning section.

May be asking too much, but thought I'd ask

[madkaw]

Not sure I know how to do a PDF file. I just barely get by with the computer stuff!!

I do plan on taking pics of the manual and posting them also. Maybe with some guidance I can make a zip file with all the pages in one folder.

Are the pages readable as I have presented them??

[spitz17]

Steve, shooting you a PM

[Travel'n Man]

Great post - thanks for the info!

[Walter Moore]

When you get those working it would be fun to have you drop by one of the Indy Z car club events.

[madkaw]

Walter,

love to do that. Don't ever mind showing off the Z!

As far as the Mikuni info, another member has volunteered to make a PDF file and host it. I am in the process of scanning the stuff and sending it to him now, so hopefully this will be available soon.

[madkaw]

As I press on with my install of the Mikuni's I will try and document the process with pictures and also note things of interest or things to be aware of.

First of I will make note of the Mikuni shorty manifold and the issues with it. Mitchell will testify that mounting it is a pain in the a$$. Because the runners turn sharply there is little room for the studs and nuts. If the studs are too long you will run into issues with them hitting the manifold and the manifold not seating properly. So the studs MUST be correct. I was supplied with studs with my kit, but they were so short I only got a few threads in some of the nuts. Since my SU's were mounted on studs, I just tailor fitting them by cuttting of threads until I got the proper length-again, a lot of work.

Also, the Mikuni manifold comes in contact with the thermostat housing. It is subtle and could be over looked until you started it up and noticed the huge vacuum leak. The flange on the housing where the aft bolt runs thru is too thick and causes the bolt head to hit the manifold. I just ground down the flange thickness so the bolt would clear. I also had a small clearance issue with the "bowl" part of the housing, or widest part of the housing-it is also close clearance on the intake.

The Mikuni manifold was the correct thickness to match the MSA header flange-so the washers work welll to secure everything.

The Mikuni manifold is tapped on every runner for -whatever. One hole is larger, #6, so it is good for brake vacuum size hose. All the rest are 1/8"NPT. I decided to gang all the ports together into a vacuum log. Note: I had to chase all the holes with a tap to get the barb fitting to screw all the way in.

Another note: the diameter of the ports on the intake runners are considerably smaller then the ports on the head . This is purposely done as anti-reversion. My manifold was built specifically for the Z car and I believe Mikuni knows what there doing. It does look way different then the SU manifold, but don't be tempted to port match the manifold to the gasket-unless you making a screamer. I thought I had a pic, but I can't find it right now.

Edited April 27, 2012 by madkaw

[madkaw]

Looking for a cheap way to fuel these triples would have been to use the original mechanical pump and regulator. The kit I got actually had some kind of reducer bushing that went inline with the original fuel line to reduce pressure I believe. I will post up the instructions to help better understand.

I went with the RX-7 pump, or a replacement pump for the RX-7. Rock-auto had them for a little as 40$ with everything you need-bracket, connecting hoses and clamps, and also an inline filter. I have read many good reports on them as being quiet and they also operate at the optimum pressure-2.5psi-4psi.

I attached mine to the floor in the hatch area. My car is very different then most since I run a centered tank and dual exhaust. It was tight and mounted the pump with some rubber to hide the noise. The pump gives off a slight padder sound that you can't hear when the car is running. I believe the pump was a Tilex.

The regulator is a Holley 1204. The fuel pressure guage is just a Summit guage, but it did come with a 90 degree fitting which was cool. Prepare to get adapter fittings for everything else on the regulator. The regulator comes 3/8NPT threads-which is way big for a 5/16" fuel line. I actually cut-off the original feed line and reused it by utilizing compression fittings. I flared the ends that hooked up to my filter so the hose had a good grip and didn't leak. I ran a clear filter to see how clean things are. I decided to NOT run return line. The kit I recieved had bango bolt fitting to run the fuel either way. So far no leaks!

[madkaw]

As far as linkage to operate the triples, the cable method would probably be best. It takes up less room and has less moving parts and people seem to be happy with the results--so that's why I did the rod linkage:)

Actually the kit provided some pieces to utilize the stock Z linkage, but I couldn't figure it out or I think I am missing some parts. I just had to come up with something to bridge between the firewall and the Mikuni linkage. I scrounged around(never throw away anything;)) and found something that I could modify that had a ball end on it.

The stock linkage for the carbs seems pretty stout. I have read of the Webers linkage being weak, but I don't see that with the Mikuni. Time will tell if my set-up will be smooth enough and strong enough. I haven't driven the car yet with the Mikuni's. The challenge for me is the enrichment linkage. I want to run the enrichment(chokes) for ease of starting and to keep from having to drown the carbs with fuel from the accelerator pumps to keep it running on a cold start. The problem is that I need to run a cable choke set-up and I'm running out of room with the linkage I have now. This is where the cable set-up would be beneficial in that I would gain room for the enrichment cable.

[madkaw]

Well I wish I would be reporting that the Mikunis are up and running- but there not:(

I will say that I have been talking to Todd at Wolfcreek and I am impressed. He might come off as gruff at first, but just think about all the dumb calls he gets. So if you plan on calling him for help or advice- be prepared to answer SPECIFIC questions and prepare to LISTEN.

Right now I have a decent idle and the car will rev-up well, but it actually stalls during a slow transition from idle. I have to adjust out the primaries 3 turns to get the car to idle. I have 57.5 primaries in there now.

180 main air

140 main jet

45 acceler nozzles

Todd recommended that I make sure the accelerator pumps are working. Sometimes it takes a while for them to prime. Also, check your floats by hanging them on their seats and measuring.

I can't way to drive and test out my CAI!

[madkaw]

This is AWESOME! Would it be possible to make a PDF of the booklet and post it? Especially the tuning section.

May be asking too much, but thought I'd ask

Just thought that I would mention that I found the MANUAL on this site and hybrid in PDF format. Just google and you will find it. I will post up the link when I can.