2.8 V6 Carbed Cologne HELP
Discussion
Okay I have never owned a carbed car before so forgive my ignorance.
About a month ago I collected a Ginetta G28 (basically a plastic capri) that came with a carbed 2.8 v6. When I got it, it seemed to be down on power and didn't idle particularly well, I was told that it has a performance cam on it so figured that explained the lumpy idle.
After driving it for a while I thought I would give it a tune up, I took it for a decent drive to make sure it was properly warmed up, turned it off and went to adjust the mixture screws to find they were both wound right in??
I set the speed screw to 1/2 turn after contact and mixture screws to base mixture (1 turn out) Turned it on and it seemed to run loads better, the lumpy idle was gone and it had more power. Great I thought.
Still seemed okay the next day but the idle was a little lumpy which attributed to being cold. Over the week it slowly got worse and by the end of the week the idle was really rough and it hated driving at 1.5kprm very stuttery. Managed to use 45L in 110 miles... 10mpg
Went to give it another tune last night and the only way I could sort the idle out at all was to turn both the mixture screws right in again. I have since noticed that the vacuum gauge sits at around 10 inches which seems low to me and points the finger towards a vacuum leak?
Started up this morning a little lumpy, as the engine warmed up and I cruised at 60 it returned to being very happy and free revving then once I got into a bit of start stop traffic in town the idle got progressively worse until it would stall if I didn't keep the throttle open.
All help gratefully accepted
About a month ago I collected a Ginetta G28 (basically a plastic capri) that came with a carbed 2.8 v6. When I got it, it seemed to be down on power and didn't idle particularly well, I was told that it has a performance cam on it so figured that explained the lumpy idle.
After driving it for a while I thought I would give it a tune up, I took it for a decent drive to make sure it was properly warmed up, turned it off and went to adjust the mixture screws to find they were both wound right in??
I set the speed screw to 1/2 turn after contact and mixture screws to base mixture (1 turn out) Turned it on and it seemed to run loads better, the lumpy idle was gone and it had more power. Great I thought.
Still seemed okay the next day but the idle was a little lumpy which attributed to being cold. Over the week it slowly got worse and by the end of the week the idle was really rough and it hated driving at 1.5kprm very stuttery. Managed to use 45L in 110 miles... 10mpg
Went to give it another tune last night and the only way I could sort the idle out at all was to turn both the mixture screws right in again. I have since noticed that the vacuum gauge sits at around 10 inches which seems low to me and points the finger towards a vacuum leak?
Started up this morning a little lumpy, as the engine warmed up and I cruised at 60 it returned to being very happy and free revving then once I got into a bit of start stop traffic in town the idle got progressively worse until it would stall if I didn't keep the throttle open.
All help gratefully accepted
luke g28 said:
plasticpig said:
Do you know what type of carb it is? Pierburg Solex, Weber 38DGMS or 38DGAS or even a Holley 8007 are likely candidates. Is it manual or auto choke?
Weber 38DGMSIts a Weber 38 with manual choke, im pretty sure DGMS is manual and DGAS is automatic?
Well that rules out the Autochoke playing silly buggers. Do you have a K&N air filter housing by any chance?plasticpig said:
luke g28 said:
plasticpig said:
Do you know what type of carb it is? Pierburg Solex, Weber 38DGMS or 38DGAS or even a Holley 8007 are likely candidates. Is it manual or auto choke?
Weber 38DGMSIts a Weber 38 with manual choke, im pretty sure DGMS is manual and DGAS is automatic?
Well that rules out the Autochoke playing silly buggers. Do you have a K&N air filter housing by any chance?If the cam is non standard then the carb jetting could be all over't shop, however you say it ran ok for a while which means something is changing. Flooding float chamber would be a candidate.
At least do the basic checks - float level, float not punctured, needle valve not leaking, see what jets are in there and check them against the OE list, make sure the choke linkage is not sticking, blow out the jets.
Read this.
http://www.pumaracing.co.uk/diagnose.htm
Do a compression test and check the cam and ignition timing to first make sure you aren't chasing a mechanical problem.
If the cam is non standard it would explain the low vacuum reading.
At least do the basic checks - float level, float not punctured, needle valve not leaking, see what jets are in there and check them against the OE list, make sure the choke linkage is not sticking, blow out the jets.
Read this.
http://www.pumaracing.co.uk/diagnose.htm
Do a compression test and check the cam and ignition timing to first make sure you aren't chasing a mechanical problem.
If the cam is non standard it would explain the low vacuum reading.
Edited by Pumaracing on Tuesday 18th January 11:30
luke g28 said:
plasticpig said:
luke g28 said:
plasticpig said:
Do you know what type of carb it is? Pierburg Solex, Weber 38DGMS or 38DGAS or even a Holley 8007 are likely candidates. Is it manual or auto choke?
Weber 38DGMSIts a Weber 38 with manual choke, im pretty sure DGMS is manual and DGAS is automatic?
Well that rules out the Autochoke playing silly buggers. Do you have a K&N air filter housing by any chance?Two set of problems that I have experienced with the K&N. For whatever reason it seemed much more likely to produce carb icing. The second problem is that at low speeds it is drawing in hot air from the engine as it doesn't extend over the edge of the engine . The pan filter pulls in air from a far bigger area.
Pumaracing said:
If the cam is non standard then the carb jetting could be all over't shop, however you say it ran ok for a while which means something is changing. Flooding float chamber would be a candidate.
At least do the basic checks - float level, float not punctured, needle valve not leaking, see what jets are in there and check them against the OE list, make sure the choke linkage is not sticking, blow out the jets.
Read this.
http://www.pumaracing.co.uk/diagnose.htm
Do a compression test and check the cam and ignition timing to first make sure you aren't chasing a mechanical problem.
If the cam is non standard it would explain the low vacuum reading.
Thanks for the link ive been scouring google for relevant information but a lot of it tends to be a bit contradictory, hence posting on here.At least do the basic checks - float level, float not punctured, needle valve not leaking, see what jets are in there and check them against the OE list, make sure the choke linkage is not sticking, blow out the jets.
Read this.
http://www.pumaracing.co.uk/diagnose.htm
Do a compression test and check the cam and ignition timing to first make sure you aren't chasing a mechanical problem.
If the cam is non standard it would explain the low vacuum reading.
Edited by Pumaracing on Tuesday 18th January 11:30
The low vacuum reading isnt explained by the cam because when I first started driving it, it read circa 20 inches. Which as I said points to a vacuum leak. However I would have thought that this would give a very lean mixture whereas I seem to be suffering from a rich one? Judging by the mixture adjustments and mpg. I don't get lots of black smoke or any pops / bangs tho.
Im sure your basic checks are straightforward enough to do but having no experience of a carb im afraid they aren't obvious 30 second checks for me...yet.
Check the valley/inlet gasket very prone to failure on the cologne(goes hard & brittle then gets sucked down the inlet ports)kept me busy when the EFI version was in it's heyday 
symptom poor idle & blowing back through the intake 
seem to remember that putting youtr hand over the oil filler opening briefly improved idle when the problem was present 
but it was a long time ago now 
symptom poor idle & blowing back through the intake seem to remember that putting youtr hand over the oil filler opening briefly improved idle when the problem was present but it was a long time ago now Edited by Simon says on Tuesday 18th January 12:04
Simon says said:
Check the valley/inlet gasket very prone to failure on the cologne(goes hard & brittle then gets sucked down the inlet ports)kept me busy when the EFI version was in it's heyday symptom poor idle & blowing back through the intake seem to remember that putting youtr hand over the oil filler opening briefly improved idle when the problem was present but it was a long time ago now
Hmmm vacuum gauge is now ready 5 inches on a warm idle, pretty sure this means its a vacuum leak somewhere however I would expect this to make the car run very lean, not the other way around :S symptom poor idle & blowing back through the intake seem to remember that putting youtr hand over the oil filler opening briefly improved idle when the problem was present but it was a long time ago now Edited by Simon says on Tuesday 18th January 12:04
Also on further investigation the carb has a warm water feed so icing shouldnt be a problem.
Edited by luke g28 on Tuesday 18th January 14:59
Simon says said:
Check the valley/inlet gasket .....
I spent ages trying to figure out the problem with one I owned a few years ago, ended up buying a Crypton machine/tuner off Ebay for £50!
Found the problem in about 20 minutes.
I've still got the Crypton machine so if you fancy a trip up to Skegness......
skeggysteve said:
Simon says said:
Check the valley/inlet gasket .....
I spent ages trying to figure out the problem with one I owned a few years ago, ended up buying a Crypton machine/tuner off Ebay for £50!
Found the problem in about 20 minutes.
I've still got the Crypton machine so if you fancy a trip up to Skegness......
but i have 2 in the workshop that have not been booted up for ages as i don't get many dizzy cars in nowadays,the diagnostic scanner gets plenty of use though 
I still have a Sun MGA 1200 4 gas ex analyser too that's been superseded by later Crypton gear also luke g28 said:
Also on further investigation the carb has a warm water feed so icing shouldnt be a problem.
There should not be a water connect to a manual choke carb - the manifold is water heated not the carb - water connections to the carb generally indicate an automatic choke. As asked previously do you know what carb you have or are you just guessing? - The model is stamped on the side of the baseplate.Also where are you measuring vacuum - from the easy to access port on the carb or independantly to the manifold plenum because the carb port is sometimes "timed"
Andrew
Darkspeed said:
luke g28 said:
Also on further investigation the carb has a warm water feed so icing shouldnt be a problem.
There should not be a water connect to a manual choke carb - the manifold is water heated not the carb - water connections to the carb generally indicate an automatic choke. As asked previously do you know what carb you have or are you just guessing? - The model is stamped on the side of the baseplate.Also where are you measuring vacuum - from the easy to access port on the carb or independantly to the manifold plenum because the carb port is sometimes "timed"
Andrew
Tbh I am taking vacuum from the vacuum gauge on the dash I haven't resolved where that is plumbed in as yet.
As I said its the first time ive been under the bonnet on a carbed car, the main issue is to sort out the fuel consumption then I can worry about getting the most out of it
oakdale said:
Does the carb have a fuel return to tank pipe as well as the feed pipe?
You say it has a DGMS carb, I doubt it would have come with this so it will be a replacement one, is it a Spanish made one?
I'll try again but word it differently.You say it has a DGMS carb, I doubt it would have come with this so it will be a replacement one, is it a Spanish made one?
Is it a replacement Spanish made DGMS?
Is there a fuel return pipe from the carb?
oakdale said:
oakdale said:
Does the carb have a fuel return to tank pipe as well as the feed pipe?
You say it has a DGMS carb, I doubt it would have come with this so it will be a replacement one, is it a Spanish made one?
I'll try again but word it differently.You say it has a DGMS carb, I doubt it would have come with this so it will be a replacement one, is it a Spanish made one?
Is it a replacement Spanish made DGMS?
Is there a fuel return pipe from the carb?
How do I know if the carb was made in Spain or not? Or are all 38 DGMS Spanish?
There looks to be 2 fuel pipes connected to the carb, I don't *think* they both run to the fuel tank but I will have a look to resolve.
If it's got two pipes, it most likely one is a return pipe.
The reason I ask is because the Spanish made one I had would flood all the time when used with a fuel regulator instead of a return pipe.
I think your problem is flooding caused by the float valve allowing too much fuel into the float chamber, so I'd look at that first.
The two Spanish ones I have seen have solid brass float valves (the inner part) with no coating on the tip and these give trouble, if you've got on of these, try to source one with a coated tip.
The reason I ask is because the Spanish made one I had would flood all the time when used with a fuel regulator instead of a return pipe.
I think your problem is flooding caused by the float valve allowing too much fuel into the float chamber, so I'd look at that first.
The two Spanish ones I have seen have solid brass float valves (the inner part) with no coating on the tip and these give trouble, if you've got on of these, try to source one with a coated tip.
luke g28 said:
plasticpig said:
Do you know what type of carb it is? Pierburg Solex, Weber 38DGMS or 38DGAS or even a Holley 8007 are likely candidates. Is it manual or auto choke?
Weber 38DGMSIts a Weber 38 with manual choke, im pretty sure DGMS is manual and DGAS is automatic?
Weber 38DGAS with a 30 offset underneath.
So I guess that makes it a dgas but it definitely has a manual choke and I have noticed quite alot of brown staining on the inlet manifold. Does this suggest air/fuel is being blown out of the inlet manifold? Even so it would have to be a vast qty to explain the current consumption.
Pics to follow when I find a cable.
Edited by luke g28 on Thursday 20th January 14:05
Carb stamping and also my mixture screws that dont look like any other pictures ive seen of a 38 dgas ??
This appears to be some sort of breather going into the passenger side rocker cover, not sure if this crack is a problem or not.
This is on the end of a vacuum pipe, I dont know what its for or what it does but did notice some sort of smoke / steam / gas coming out of the other night. You can just make out a wisp of it in the picture.
Edited by luke g28 on Thursday 20th January 20:32
Carb is a 38 DGAS 3C - the 3C indicates the model and the various jets installed - fitted with aftermarket manual choke kit by the sounds of it
Breather would have gone to the original air cleaner - As its venting it indicates a tired engine
The carb isolator - the black bit under the carb - looks very tired.
Carb bases can warp with age causing air leaks
Your issues could just as well be electrical though.
Andrew
Breather would have gone to the original air cleaner - As its venting it indicates a tired engine
The carb isolator - the black bit under the carb - looks very tired.
Carb bases can warp with age causing air leaks
Your issues could just as well be electrical though.
Andrew
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