BCDD Rebuild Parts

[Captain Obvious]

Thanks for the parts digging guys. I'll probably go the used route before resorting to buying new.

Don't get me wrong about my PO. It's not like he blasted the inside of the throttle body. It's clear that he at least tried to keep the grit out of places it shouldn't go. Problem is that even if you're careful, grit sometimes gets where it shouldn't. So, it's not like I'm expecting to dump a spoonful of grit out from inside my BCDD, but it only takes one bead on the sealing surface of the valve inside to screw it up.

Do I think there's a spoonful in there? No.

Do I think there's a piece or two in there? Absolutely.

[FastWoman]

Wowza! Here I was admiring your sparkly clean engine. I had no idea how it got that way and what the implications were!

[Captain Obvious]

Wowza! Here I was admiring your sparkly clean engine. I had no idea how it got that way and what the implications were!

Yeah, no kidding. The implications, as I'm finding out, are deep running.

So not only am I finding blasting grit in places it shouldn't be, I've also realized that all of the original chromate plating has been blasted off the steel bits and has been replaced with paint. Looks great until the first time you wipe something with carb cleaner and take the paint off exposing the untreated steel beneath.

I would much rather deal with a little dirt, grease, oxidized aluminum, and old chromate. Even if it's starting to fail in spots.

[rcb280z]

Old thread I know but, did you find any replacement parts for the BCDD Capt.? Or anyone for that matter. I believe my BCDD has a vacuum leak and am thinking about removing and blocking it off. But I'm not sure what to do about the solenoid. Here's the reason. When I unplug it the idle changes (lowers) and is not as smooth. And when I rev the engine the idle is slow to return to 800. This is while the solenoid is unplugged.

My other concern is emissions. It is hard to pass emissions testing as it is in California. What will it do if its removed? I'm not sure.

I don't want to purchase a used one because it could have the same problems mine has and if it doesn't when will it? There are no new ones that I can tell.

The other thing I noticed with my BCDD is when I was standing over the engine just listening (with BCDD solenoid connected) I heard this "click" sound and the engines idle changed. Was not smooth. Acted as if it just became lean. It stayed that way for a few minutes and then I heard another "click" and the idle smoothed out, What?! Not sure whats going on there either. 

[Captain Obvious]

I'm sorry, but I never found any replacement parts for the BCDD.

 

I know mine leaks a little as well, but it's an "internal" leak, not an external one. By that, I mean, my BCDD passes a little air through it even when it's not supposed to, but it passes from one side of the throttle plate to the other. It doesn't leak from outside the manifold to inside.

 

So I've just got my idle speed screw set such that the total air around the plate (addition of what goes through the BCDD plus what goes around the idle speed screw) to my desired idle. I adjusted the idle speed screw and forgot about my leak.

 

If you're is leaking to the outside world, then that's a more serious issue.

 

And the thing about the clicking... That shouldn't be happening. I guess I'll get into the details in the other thread?

[rcb280z]

Hey Capt. I started a new thread regarding my issue. Thanks for responding. You'll see it. 

[Volkmeister]

Hopefully this isn't a completely dead thread but I'll put it out there anyways. 

Regarding this topic, I've had BCDD issues on both of my Z's 1976 280Z and 1980 280ZX. Both times due to tears in diaphragms. I just ended up machining a blocker plate, RTVing the bypass on the AFM side, and plugging the manifold side. I still have some blocker plates and rubber plugs laying around if anyone still has this issue

On another note, I'm going to mold some new diaphragms and do a write up on how to rebuild the BCDD... if successful of course. After disassembly and reverse engineering some parts it seems feasible to return the function of the BCDD rather than blocking it off.

Hope you guys got it figured out since then though. It gave me headaches when I first ran into it.

[S30Driver]

3 hours ago, Volkmeister said:

Regarding this topic, I've had BCDD issues on both of my Z's 1976 280Z and 1980 280ZX. Both times due to tears in diaphragms. I just ended up machining a blocker plate, RTVing the bypass on the AFM side, and plugging the manifold side. I still have some blocker plates and rubber plugs laying around if anyone still has this issue

I would be interested in a plate & plugs if still available.

[Volkmeister]

1 hour ago, S30Driver said:

I would be interested in a plate & plugs if still available.

No problem, I'll check and see what I have in the box-o-projects this evening. The plate and plug method works without RTV. The only reason I RTVd the first time was a lack of plug. But I can send you install details as well. 

[S30Driver]

3 hours ago, Volkmeister said:

No problem, I'll check and see what I have in the box-o-projects this evening. The plate and plug method works without RTV. The only reason I RTVd the first time was a lack of plug. But I can send you install details as well. 

Sounds great!

[Volkmeister]

@S30Driver good news! Neoprene plug material came in sooner than I thought. I can send it out first thing Monday.

For anyone else:

They can be made fairly easily, but if you don’t care to toil with cutting and drilling a plate or using RTV I’ve got 10 plug kits available. Works very well on my 76 280z for the last 2 years, as well as the 1980 280zx throttle body pictured below. If there’s any doubt send me a picture of the throttle body and I’ll be able to tell. 

The kit has: a CNC Machined Blocker Plate, 1” Neoprene Crush Plug, and 3mm Button Head Screws (3), seal material (not pictured). Initially I re used the seal at the throttle body and it worked well but fashioned a new one later on because I wasn’t comfortable with how brittle it was. When I get my CNC router/laser back up and running I’ll cut some finished gaskets for the next batches.

Anyways just message me or follow the link on my page to my eBay shop. If you’d like to make one yourself and don’t know how to go about it, I can help you there too. So feel free to ask for help. 

In the mean time I’m still working on rebuild parts and fabricating diaphragms for the BCDD... mainly because I like a challenge, but I think I can restore true stock functionality of it... which is not entirely necessary ?‍♂️ but may be some people’s flavor.

 

[rcb280z]

13 hours ago, Volkmeister said:

I can restore true stock functionality of it... which is not entirely necessary ?‍♂️ but may be some people’s flavor.

.....and is good for those that have to pass emissions testing that requires a functional one.

Edited August 10, 2019 by rcb280z