I've got a 73 Nikki carb on the RX-2. Same deal as RX-7. Last time I rebuilt the carb (a month ago) I took apart the secondary diaphragm assembly and it was full of fuel/oily mixture. Why is this, how do I prevent this from happening again, and how do I know when to drain the goo out before it causes the secondaries not to open?

thanks in advance

 

No idea!

Only thing I can think is that overexuberant use of carb cleaner/starting fluid got it in there.

 

I've encountered this a few times on older carbs. Never on a 83-85 carb.
At first I thought maybe the oil was put in by Hitachi to smooth out the vacuum opening, but of the few that I've found with oil, the amount is never consistant.
So after rethinking this puzzel, I came to the conclusion that the oil wouldn't really fioll the vacuum signal circuit to the primary bore, so then I thought about it being added with the idea of air volume displacement. (?)

I dunno, but I can't figure ANY way that it got there by accident.

 

Sterling, thanks for the reply. I can tell you this with assurance. I rebuilt this carb (73 Nikki) 2 years ago. The diaphragm in question was in great shape, so I just cleaned everything up and put it back in (was full of oil at this point too). The car blew the original engine about 6 months later and it was parked for 18 months while new engine and transmission were converted in.

After getting the car running I spent about a month trying to get it running well. Part of the troubleshooting process was to put new needles/seats in the carb so when I tore it down I opened up the secondary diaphragm - full of the oil/fuel mixture again.

So somehow, when the engine is on heavy load (i.e. < 5 lbs vacuum) goo is getting blow into that circuit and accumulating in the assembly.

A mystery indeed . . . thanks for replying.

Dave

 

Ever had oil in your distributor's vacuum canisters? I've seen it twice.

 

yes I've had that . .