Slant *        6        Forum
Home Home Home
The Place to Go for Slant Six Info!
Click here to help support the Slant Six Forum!
It is currently Thu Mar 28, 2024 1:48 am

All times are UTC-07:00




Post new topic  Reply to topic  [ 27 posts ]  Go to page 1 2 Next
Author Message
 Post subject: BBD operation
PostPosted: Tue Jan 23, 2018 5:12 am 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
looking down into my BBD to see the accelerator squirt. . .
i get a good blast of fuel from both jets.
i notice that it lasts about 25% of the time it takes to move the gas pedal close to the floor.
is this normal? or is my blast being cut short?

i am chasing a bog below 1500 RPM.
trying to determine if i should first look into the BBD or the distributor.

:?:


Top
   
 Post subject: Re: BBD operation
PostPosted: Tue Jan 23, 2018 6:20 am 
Offline
Supercharged
User avatar

Joined: Sat Feb 16, 2008 1:25 pm
Posts: 5599
Location: Downeast Maine
Car Model:
At 1500 or lower rpm carb is running on idle and transition circuits for lack of a better term (i know these devices utilize rods and jets) and main has not kicked in, in other words it's probably already on lean side, and when intake see a lot of blue sky during large sudden throttle opening mixture goes real lean until main can get flowing. 1500 rpm is not moving much air through carb, so as you suspected, a longer duration accelerator pump shot is probably needed.

Not being up on BDD's, just how one extends pump shoot, I can't say, but I'm sure someone will chime in on such a fix.

_________________
67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Image


Top
   
 Post subject: Re: BBD operation
PostPosted: Tue Jan 23, 2018 11:21 am 
Offline
Board Sponsor & Contributor

Joined: Thu Oct 31, 2002 5:39 pm
Posts: 24233
Location: North America
Car Model:
You normally won't see a pump shot lasting the entire time it takes to open the throttle (unless you open it really fast). Carburetor operation and repair manuals and links to training movies and carb repair/modification threads are posted here for free download, but the problem isn't necessarily coming from the carburetor. More detail about this "bog below 1500 rpm" will help you narrow in on it; that description isn't specific enough. What kind of car is this on, is it original or a transplant, what's the history of the carb, where'd it come from, what emission controls are (still) in place and operational, what ignition system are you running, what changed before the "bog" started happening, what exactly do you mean by "bog" and "below 1500 rpm", etc...

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Image


Top
   
 Post subject: Re: BBD operation
PostPosted: Tue Jan 23, 2018 11:56 am 
Offline
Supercharged
User avatar

Joined: Sun Nov 03, 2002 9:20 pm
Posts: 13008
Location: Fircrest, WA
Car Model: 76 D100
Whenever diagnosing BBD issues, my first question is whether the metering rods are adjusted properly. The metering rod setting plays a big role in how a BBD performs. Check your metering rod adjustment.


Top
   
 Post subject: Re: BBD operation
PostPosted: Thu Jan 25, 2018 5:27 am 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
Reed,
i believe i have the meter rods set correctly. i have them at the longest stroke i can get. i have the correct /6 riser arm in place. that other adjustment at the top of the needle assembly is what i don't know about. the manuals say to leave that thing alone. i have no idea if it was ever messed with b4 me.


Dan,

this is a transplant BBD onto what is other wise a stock 225 in a 68 A108.
the bog started when i first put the BBD on it many years ago. i just learned to deal with it because i mostly just use the van for long freeway cruises and it does real nice up at speed.
a few months ago i realized i was running an 8 Cyl BBD while i had a 6 cyl version at my disposal. i don't recall where i got it. probly a swap meet or Ebay.
u, and others here, helped me get the idle down where it should be by helping me realize i had the wrong throttle plates in place.
the bog is identical between the 2 carbs, so either they r both perfectly out of adjustment in exactly the same way or it is something else?
i tried advancing the distributor. it is currently set at 2-3* BTDC. if i bring up to about 10* the bog lessens. but then i get a lot of pinging under loads at higher speeds.
i really suspect the distributor, but i want to try to get the BBD as close to spot on b4 i get into the dizzy.


Top
   
 Post subject: Re: BBD operation
PostPosted: Mon Jan 29, 2018 2:18 am 
Offline
Turbo EFI

Joined: Sat Feb 18, 2006 2:19 pm
Posts: 1601
Car Model:
http://www.slantsix.org/forum/viewtopic.php?f=19&t=35294&hilit=metering+rod


Top
   
 Post subject: Re: BBD operation
PostPosted: Fri Feb 02, 2018 5:17 am 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
thang Q. i had not seen that b4.


Top
   
 Post subject: Re: BBD operation
PostPosted: Sat Feb 24, 2018 4:35 pm 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
just a qwik "Thang Q" to all that offered ideas.
the link to the metering rod set up was the key.
i got in and set it to the .035 today and the old van woke right up.
i think i'll be fiddlin with it a bit more, and after that i'll get into the distributor.
itz almost ready for another run out to the 4 Corners Area.

thanks again.

D~~~!


Top
   
 Post subject: Re: BBD operation
PostPosted: Sun Feb 25, 2018 1:36 am 
Offline
Board Sponsor
User avatar

Joined: Fri Nov 01, 2002 5:29 pm
Posts: 963
Location: Eustis, FL
Car Model: '68 V100, '68 V200, '79 Aspen, '84 D100
I'd put a kit in the BBD so I know I have a fresh pump (#25). Make SURE the metering rod arm (#22) and pump arm
(#23) are properly adjusted. Only then I would adjust the step up piston (#11) if needed.


Image

_________________
Slant Cecil


Top
   
 Post subject: Re: BBD operation
PostPosted: Sun Feb 25, 2018 8:22 am 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
this was a carb i didn't realize i had. i don't recall where i got it. probly Ebay or a swapmeet.

i did go thru it and freshen things up. and it ran just fine once i got up to speed. it just felt weak during acceleration.
yesterday i did find the piston specs was very lean. a simple adjustment and it is much more normal.


Top
   
 Post subject: Re: BBD operation
PostPosted: Wed Feb 28, 2018 7:04 pm 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
now that i am getting over the initial surprise in the difference in performance,. . .

do the metering rods come in different sizes? r they stamped/marked as to what size they r? where?
same questions for the jets the rods run thru?
r there any data/charts somewhere detailing what rods-jet combinations should best be applied for different altitudes?

still some adjusting to do. . .

trying to think out all the variables.


Top
   
 Post subject: Re: BBD operation
PostPosted: Thu Mar 01, 2018 3:03 am 
Offline
Turbo EFI

Joined: Sat Feb 18, 2006 2:19 pm
Posts: 1601
Car Model:
viewtopic.php?f=19&t=55207&hilit=spring


Top
   
 Post subject: Re: BBD operation
PostPosted: Thu Mar 01, 2018 3:17 am 
Offline
Turbo EFI

Joined: Sat Feb 18, 2006 2:19 pm
Posts: 1601
Car Model:
Meter rods different sizes yes, also different step-up spring. Sedans soft spring, heavy station wagons got stiffer spring.What numbers on your rods?


Top
   
 Post subject: Re: BBD operation
PostPosted: Thu Mar 01, 2018 6:01 am 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
i did not notice any markings on them. that is why i asked.
where r they marked?
i will have to take them out to find which ones they r.
maybe over the weekend.
it would help to know where to look because i missed it so far.


Top
   
 Post subject: Re: BBD operation
PostPosted: Thu Mar 01, 2018 6:19 pm 
Offline
EFI Slant 6
User avatar

Joined: Sat Nov 08, 2003 8:14 pm
Posts: 298
Location: West Covina, CA
Car Model: 1968 A108 225/3 on the tree
oh.. .

my BBD lives in an A108 van.
i would guess that means it should get the heavier spring?


Top
   
Display posts from previous:  Sort by  
Post new topic  Reply to topic  [ 27 posts ]  Go to page 1 2 Next

All times are UTC-07:00


Who is online

Users browsing this forum: No registered users and 105 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Powered by phpBB® Forum Software © phpBB Limited