Hi all,
So im still working on these carbs and im having some success but we fired it up and it ran ok only to die out, had a look in the manifold under the carbs and one was soaking with fuel (front carb)in the manifold, and the other not. So i swapped the two carbs over to see if it was an issue in the carb, nope same again the front carb soaking the back one fine,.
When it runs i can feel the rear carb sucking really hard and the front carb almost not at all, so im thinking vaccum issues to the front carb,
I havent noticed any vacuum leaks anywhere but again this is not my field of expertise
Has anyone encounted anything like this, if so what are some suggestions for increasing the vacuum on the front carb toget the fuel tot the motor
Cheers again for any assistance
Vacuum issues dual Carburetor
- DumpRat
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- Location: T-Ville NQ
Vacuum issues dual Carburetor
Remember : Manners Cost You Nothing but Get You Everything ....
- FRANK BASILE
- Old Hand
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Re: Vacuum issues dual Carburetor
Hi DumpRat. I must have missed the first instalment. What carby set up is it, on what engine?. From the logical steps taken that you describe it does already sound like a manifold/engine issue.
OZ-E-Rodders Rod and Kustom Club Member #31
- steve the ford guy
- Senior Member
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Re: Vacuum issues dual Carburetor
I had a similar issue with a 5litre Holden EFI, it was a poorly sealing intake manifold to intake port gasket losing vacuum, I think it's a design problem with those engines
- DumpRat
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Re: Vacuum issues dual Carburetor
Hi Frank
its a 265 hemi with dual carter BBD carbs, i have been going through some stuff trying to get it to run successfully but just isnt quite happening
origionally it was over fueling terribly as discussed in another thread
http://www.ozrodders.com/forum/viewtopi ... =5&t=65342
but now i have this issue, i will go looking for vacuum leaks soon,
the rear carb is sucking its nuts off and the front hardly anything, so i swapped the carbs around and same thing, back is good front not so.
years ago in my build thread i had photos of how i made the manifold and the internals (set it up with 2 seperate chambers and a ballance passage between them) unfortunatly all those pics are now gone and i cant get them back from imagecrap.
i am wondering if it was just one big open chamber would tht help resolve this but unsure
cheers
its a 265 hemi with dual carter BBD carbs, i have been going through some stuff trying to get it to run successfully but just isnt quite happening
origionally it was over fueling terribly as discussed in another thread
http://www.ozrodders.com/forum/viewtopi ... =5&t=65342
but now i have this issue, i will go looking for vacuum leaks soon,
the rear carb is sucking its nuts off and the front hardly anything, so i swapped the carbs around and same thing, back is good front not so.
years ago in my build thread i had photos of how i made the manifold and the internals (set it up with 2 seperate chambers and a ballance passage between them) unfortunatly all those pics are now gone and i cant get them back from imagecrap.
i am wondering if it was just one big open chamber would tht help resolve this but unsure
cheers
Remember : Manners Cost You Nothing but Get You Everything ....
- turns
- Old Hand
- Posts: 2925
- Joined: Mon Dec 17, 2007 8:23 pm
- Location: Sydney NSW
Re: Vacuum issues dual Carburetor
Hi Dumprat
Firstly, it is super difficult to diagnose this stuff on a forum
I will assume that you have checked all the usual stuff like fuel pressure, float bowl levels and much more.................
Vacuum leaks are common and can be easy or difficult to find. Everyone has their favourite techniques but I mostly use a length of hose as a stethoscope i.e. one end in a clinched fist near my ear and the other end around possible areas of vacuum leakage on the engine. You will hear a leak quickly.
The red flag I saw when reading your post was "how I made the manifold and internals". It's hard without pics but I would be having a real close revisit on your manifold design and fabrication as a source of your running issues. If you still have the factory manifold maybe swap it back and see what happens.
Good luck with sorting it out
Cheers Turns
Firstly, it is super difficult to diagnose this stuff on a forum
I will assume that you have checked all the usual stuff like fuel pressure, float bowl levels and much more.................
Vacuum leaks are common and can be easy or difficult to find. Everyone has their favourite techniques but I mostly use a length of hose as a stethoscope i.e. one end in a clinched fist near my ear and the other end around possible areas of vacuum leakage on the engine. You will hear a leak quickly.
The red flag I saw when reading your post was "how I made the manifold and internals". It's hard without pics but I would be having a real close revisit on your manifold design and fabrication as a source of your running issues. If you still have the factory manifold maybe swap it back and see what happens.
Good luck with sorting it out
Cheers Turns
"Normal is an illusion. What is normal for the spider is chaos for the fly"...............Morticia Addams
- Sudsy
- Senior Member
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- Location: Lower Mid North South Australia
Re: Vacuum issues dual Carburetor
Spray some brakeclean or similar on all the jointing surfaces while motor is running. Motor will pick up in revs wherever it sucks through the joint. That should tell you where it's leaking
Regards Bob
- FRANK BASILE
- Old Hand
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- Joined: Wed May 07, 2003 3:14 pm
Re: Vacuum issues dual Carburetor
Did this get fixed?. Something else from my Valiant days had that carby particularly prone to air leaks due to warping distortion of the top cover when over zealous with tightening the screws. In this case though the carbs were swapped and the condition existed still in the same position. Me thinks still a manifold/engine issue.
OZ-E-Rodders Rod and Kustom Club Member #31
- DumpRat
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- Joined: Tue Nov 02, 2010 10:59 am
- Location: T-Ville NQ
Re: Vacuum issues dual Carburetor
update
we have it idling ok now just trying to get it to not die out under throttle, man these are some interesting carbs to work on
trial and error will find a solution eventually
hahah
cheers
we have it idling ok now just trying to get it to not die out under throttle, man these are some interesting carbs to work on
trial and error will find a solution eventually
hahah
cheers
Remember : Manners Cost You Nothing but Get You Everything ....