I recently aquired a Mikuni carb for a 12a. I'm a little perplexed as to how to deal with the OMP however. There are two ports on the bottom of the float bowl area that appear to be for the oil injection lines, however there are no linkages/provisions for the OMP. I'm not opposed to premixing - as this isn't going into a daily driver anyway. If I do premix, what's the procedure for disabling the OMP? (I couldn't seem to find it in a search).



Thanks!
dale

 

All I know is that you need a block-off plate. You should remove the OMP somehow and use the BOP so you won't be spraying oil in your enginebay.

 

THose holes near the throttle plates are for oil injection. The top holes near the accelerator pump are not for oil lines. I don't know why mikuni has those ports exactly except if the accerator diaphram pump failed, it would spill gas everywhere?

 

Also it appears you have the throttle linkage on the wrong side, you should be able to disconnect it and switch it to the other side. Did you not get a metering rod with your Mikuni kit? Or did you buy this carb from some other appication? If so, I hope you get the proper jetting for it. Which i believe for the main jets are 200 and air jets are 240. I forget which the other ones are.

 

The throttle linkage is towards the rear of the car (that isn't right?) This is a used carb/manifold bought on ebay - so who knows what it is. No other linkages were included. The stock accelerator cable is too long for this application also, but that problem isn't insumountable.

dale

 

Oh, and to followup, the two connections at the base of the carb are the only ported vacuum connections - I assumed for the distributor. There is a single large manifold vacuum which can handle everything else.

dale

 

Block it off and go premix!
https://www.rx7club.com/forum/showth...hreadid=142884

 

I took some pics of how my OMP was connected. I will post them up sometime next week if you need them.

 

Had a hell of a time blocking it off.

I went to a local carb shop and showed them the gasket for the OMP and said I needed a block off plate machined. He got out a FUEL PUMP block off plate for a type IV VW motor. Upsidedown it fit very well. Some of the plat hanged off the motor, but that was OK. Now, the oil is under a lot of pressur in there so I used Red RTV gasket sealer (high pressure) and a flat piece of steel went over the block off plate with two holes in it for the bolts. That flat steel spread the bolt's load over the entire width of the block off plate. Otherwise bolt's load was just on the ends, and it would leak in the middle.

It went on like this:
motor
red rtv
gasket
red rtv
block off plate
flat steel plate
two big fat fender washers
two bolts

Needed longer bolts too but had some spare metric ones. Put pleanty of rtv in there, including in the bolt holes.

OR, if you don't really care, just disconnect the OMP linkage and put the OMP lines in an empty plastic coke bottle! The pump does pump oil at idle, that way apex seals get lubed at idle. So simply disconnecting linkage won't stop it.

Best of Luck!
-bp-

 

Does this help any?

 

On the opposite side of my Mikuni there was a spot for my OMP rod to fit on with a nut. I put the oil lines on the ports closest to the base. It would be the bottom ones on your pic. The others are simply plugged. I will be rebuilding another motor to put in mine when it's time and I will block off the OMP and go premix then. I also use MMO with every tank of gas just in case.

 

Try this