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BCDD Rebuild Parts
Posted 15 April 2012 - 05:54 PM
the FSM says "NEVER take the BCDD apart"
Haha! Yeah I saw that too, but... So?
If they didn't want me to take it apart, they wouldn't have put screws on the bottom.
Seriously though, I suspected as much. Most discussion I've seen on the BCDD is people talking about how they have disabled them, not repaired or replaced them. I just figured I would throw the question out there and see what stuck. Was thinking (hoping?) that maybe one of the aftermarket specialists might offer parts.
Posted 15 April 2012 - 06:11 PM
You may be able to refresh tears in the diaphragms with improvised patches.
3m spray adhesive and paper can patch a ripped up speaker so there should be some way to revive a BCDD.
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Posted 15 April 2012 - 06:59 PM
1978 Coupe - HLS30-440105
Spring, Texas USA
pro deo et patria
Posted 16 April 2012 - 04:45 AM
Problem is that I sincerely doubt that I'll be able to split the BCDD parts apart without completely ruining the diaphragms. In other words, I'm not past the point of no return yet and I didn't want to pass that point until I had a "plan".
Blue, this is your fault by the way... :laugh: It all started by looking into that goofy auxiliary throttle return spring that you pointed out to me and has spiraled out of control from there. I've been trying to figure out why that additional return spring was needed to get the throttle to return to idle and I've discovered a whole host of issues that are contributors. One of the fixes (so far) was to completely disassemble and clean the throttle body. With the exception of the BCDD or course.
Posted 16 April 2012 - 06:14 AM
Posted 16 April 2012 - 06:07 PM
But the summary is that I've discovered that my previous owner got overzealous with the bead blaster and sprayed things he should not have. Here's the host I've found so far:
Blasting grit in the throttle body and TPS making the throttle shaft movement grainy.
Blasting grit making all of the throttle linkage ball and socket joints sticky.
Blasting grit in the sleeve bearings where the throttle linkage mounts onto the intake manifold.
Blasting grit inside the plastic spherical bearing where the throttle linkage mounts to the firewall.
Not related to my throttle issues, but I found blasting grit inside my distributor as well.
So what made me start looking at the BCDD? To be honest, I don't have any performance reason to believe there's anything wrong with it, but with all the grit I've found elsewhere, it is impossible for me to believe that it didn't get inside the BCDD as well. But I don't want to open it up without replacement parts first.
If you open one, I'd love to see pics. I think I've got a pretty good idea of what's inside, but without opening one up, it's simply speculation.
I just hope he spared the AFM.....:sick:
Posted 16 April 2012 - 08:11 PM
Posted 17 April 2012 - 04:25 AM
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.
Posted 17 April 2012 - 07:19 PM
Current Z: 1978 280Z, mostly stock, with some electrical mods. Semi-daily driver.
First Z: a brilliant, gold, 1975 280Z for my daily commute.
Also in the fleet: '94 Miata, '92 Saturn SL2, and '09 Dodge Ram (token modern vehicle).
Posted 18 April 2012 - 03:57 AM
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.
Posted 15 January 2015 - 08:05 AM
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.
Posted 15 January 2015 - 07:12 PM
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?
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