Guys, I have an 85 Alto Van F5a engine.......when my mechanic fitted the new motor, he told me the second stage of the carby was not opperating, this has been confirmed by a second mechanic.
How do I rectify this problem to get the full power of my massive F5a.
Any hints will be welcomed.
Thanx.....Greg.
Carby Question
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turbo-hatch
- Posts: 11
- Joined: Sun Jun 05, 2005 8:33 pm
- Location: adelaide
take the pipe off that feeds the second avccum diaphram and suck on it with the throttle held open. it should move. hold the suck on it and see if it stays open. if not diaphram is toast. need to be replaced. been told that sigmas have the exact same diaphram
size doesnt count for nothing,if ya not gettin BLOWN!
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turbo-hatch
- Posts: 11
- Joined: Sun Jun 05, 2005 8:33 pm
- Location: adelaide
standing in front of the car looking at the carby, on the left hnad side front of thecrab. looks like a little flying saucer. abouth the size of a buscuit.has a small spring loaded arm the comes off of it that likhs don to a linkage for the second butterfly on the carby
size doesnt count for nothing,if ya not gettin BLOWN!
Thanks to everyone who has helped me with my carby problem.......I have found the diaphram and snapped off the perished hose ( accidently of course ) I have then taken it for a run without the hose and it makes absolutely no difference in performance.
Could this be the tell tale sign that the diaphram is buggered ?
If so, how do I get it out of that little round housing.
Thanx.....................Greg.
Could this be the tell tale sign that the diaphram is buggered ?
If so, how do I get it out of that little round housing.
Thanx.....................Greg.
Didn't I used to be somebody once !
If the diaphragm is damaged the whole unit must be replaced. Sigma carby's sure the same one so head to the wreckers.
Once you've replaced the diapragm check that the secondary throttle hasn't siezed shut. Check this by manually opening the primary throttle, then while it is open try and turn the second throttle manually open as well. If it won't budge then you'll have to pull off the carby and rebuild it, freeing up the secondary throttle butterfly while you're at it.
If you do a search on "Carby" then you'll find a number of threads discussing this problem and possible solutions, including making a manual linkage - it is probably the most common fault on the F5A/F8B.
Once you've replaced the diapragm check that the secondary throttle hasn't siezed shut. Check this by manually opening the primary throttle, then while it is open try and turn the second throttle manually open as well. If it won't budge then you'll have to pull off the carby and rebuild it, freeing up the secondary throttle butterfly while you're at it.
If you do a search on "Carby" then you'll find a number of threads discussing this problem and possible solutions, including making a manual linkage - it is probably the most common fault on the F5A/F8B.
F8B EFI turbo - Three pots and a snail.
Brayden....thanx for your help and suggestions, I am just unsure what is happening. I have tried the sucking pipe thing and the secondry does work, there is just no difference whether this vacume hose is on or off, really weird shit,
Thanx to everyone......it's sites like these, that make owning a Suzi a joy.
Seeya......Greg.
Thanx to everyone......it's sites like these, that make owning a Suzi a joy.
Seeya......Greg.
Didn't I used to be somebody once !
If you've got some spare time mate, then have a crack at making a mechanical linkage for the 2nd throttle - trust me, you'll notice a difference then!
F8B EFI turbo - Three pots and a snail.
Guys, I hate to be a pain in the arse, but my analysis of the problem is this.......The secondary stage opens when I run a hose off the diaphram and suck with my mouth, but there is absolutely no suction what so ever coming out of the carby to activate the diaphram, hence it can't possibly open.
What does this mean ?
The car runs fine on 1 throat, but if there is more to come from this second stage.....I want it.
Help.
What does this mean ?
The car runs fine on 1 throat, but if there is more to come from this second stage.....I want it.
Help.
Didn't I used to be somebody once !
How did you diagnose the lack of suction from the carby? The vacuum is created only when the engine is under load, for economy purposes.
So if the vehicle is stationary and you give it a good rev, the secondary will not open. Only, say, when you're going up a hill.
That being said, if you are sure there is no suction at ANY time, then the carby will need to be stripped down, cleaned and rebuilt.
Some people are crazy enough to bay $300+ to have the job done, but anyone with some turps, a phillips head screwy and a rebuild kit (~$70) can do the job in an hour or two.
So if the vehicle is stationary and you give it a good rev, the secondary will not open. Only, say, when you're going up a hill.
That being said, if you are sure there is no suction at ANY time, then the carby will need to be stripped down, cleaned and rebuilt.
Some people are crazy enough to bay $300+ to have the job done, but anyone with some turps, a phillips head screwy and a rebuild kit (~$70) can do the job in an hour or two.
F8B EFI turbo - Three pots and a snail.
Thanx Brayden.........What I did was run some vacume hose from the outlet on the carby and rev the engine to around 5,500 to 6000 whilst putting my finger over the open hole at the other end of the hose......and there is zero suction, not even a hint.
As I said earlier, when I run this hose straight from the diaphram I can open and close the secondary chamber, and if I leave the Vac hose off altogether ther is absolutely no change to the engines performance.....hence my deduction that the secondary isn't getting enough suction to open it at all.
Any more info is very welcome.
Thanx heaps....Greg.
As I said earlier, when I run this hose straight from the diaphram I can open and close the secondary chamber, and if I leave the Vac hose off altogether ther is absolutely no change to the engines performance.....hence my deduction that the secondary isn't getting enough suction to open it at all.
Any more info is very welcome.
Thanx heaps....Greg.
Didn't I used to be somebody once !
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turbo-hatch
- Posts: 11
- Joined: Sun Jun 05, 2005 8:33 pm
- Location: adelaide
just tried some thing today in regards to a manual linkage secondary.and it works like a treat
here goes....
found a old spring that the use for the secondary butterfly to hold it closed.
bent one loop end so that is perfectly flat towards the out side of the spring ( running parallel with the out side orf the spring) and the other end so that it was 90 degrees to it orginal position.
then if ya look at the side of the carby where the vacum linkage for the secondarys are there is a small spigot that come off of it that does nothing( just about the other spigot that holds the acuation arm for the secondary diaphram). you place the end of the spring that is bent over parrlel on this spigot. push the rest of the spring behind the linkage so that is on on the side closest to the carby body.
the other end of the sprong, ( the one bent 90 degrees) you hook onto the primarly butterfly linkage....
the position is..... looking at the botom half of the primarly linkage, there is a small arm that looks like a bootom half of a roosters foot( where the spur is) you will see something that resembles a spur tah pints downwards. fit the other end of spring on this so that the spring body is also on the inside closest to the carby.
and there ya have it..... when ya acuate the primary butterfly,,,,, one it has gotten past the point that it allows the secondary to move if the vaccum doiesnt pull it, the spring tension will. if you have it right you will see the secondary arm move one the primary is cracked open about 2/3 of the way......
it seems to work like a treat and is very cheap to do...
will get admin to post a pic so that you can see what i mean.
AND YES, YOU CAN FEEL THE DIFFERNCE WHEN THE SECONDARY DOES OPEN!
here goes....
found a old spring that the use for the secondary butterfly to hold it closed.
bent one loop end so that is perfectly flat towards the out side of the spring ( running parallel with the out side orf the spring) and the other end so that it was 90 degrees to it orginal position.
then if ya look at the side of the carby where the vacum linkage for the secondarys are there is a small spigot that come off of it that does nothing( just about the other spigot that holds the acuation arm for the secondary diaphram). you place the end of the spring that is bent over parrlel on this spigot. push the rest of the spring behind the linkage so that is on on the side closest to the carby body.
the other end of the sprong, ( the one bent 90 degrees) you hook onto the primarly butterfly linkage....
the position is..... looking at the botom half of the primarly linkage, there is a small arm that looks like a bootom half of a roosters foot( where the spur is) you will see something that resembles a spur tah pints downwards. fit the other end of spring on this so that the spring body is also on the inside closest to the carby.
and there ya have it..... when ya acuate the primary butterfly,,,,, one it has gotten past the point that it allows the secondary to move if the vaccum doiesnt pull it, the spring tension will. if you have it right you will see the secondary arm move one the primary is cracked open about 2/3 of the way......
it seems to work like a treat and is very cheap to do...
will get admin to post a pic so that you can see what i mean.
AND YES, YOU CAN FEEL THE DIFFERNCE WHEN THE SECONDARY DOES OPEN!
size doesnt count for nothing,if ya not gettin BLOWN!
Turbo Dude..........you the man......thanx shitloads......if you've got pics, that's awesome.
I am capable of doing the Mod, if I can see exactly what needs doing.
You're a Champion.
Thanx Mate..........Greg.
I am capable of doing the Mod, if I can see exactly what needs doing.
You're a Champion.
Thanx Mate..........Greg.
Didn't I used to be somebody once !