View Full Version : Old school carbs..
Okay,
My dad and I have pretty much finished his build of his mg midget. The problem he is having is balancing of the dual carbs on the 1275 A-series. Does anybody know of anybody within the northampton area who is capable of doing this properly. Last time my dad took the initiative and took his car to a garage without asking me, they charged him £300 to swop the intake manifold and a bolt.
After having rebuilt the engine from scratch, I'd rather someone with carb experience do the final tweak.
Thanks
Is he a member of any MG forums? Sure that could be a good place to start.
Is he a member of any MG forums? Sure that could be a good place to start.
He is a member of an mg board, but from what I've seen they certainly don't have the same spirit at has been shown here. People on there are more than happy to shift bits, but my dad isn't clued up enough to ask on the forum and stuff like that. My dad isn't a technophobe, but a little bit of tech (ie computer) and it gets dangerous *grin*... He has just gotten to grips with sending me pictures via email... (Was yelling at him over the phone in Tescos the other day, because he wouldn't listen to me when I was explaining how to resize photo's to email them to me)...
Spent ages rebuilding the engine, rebuilt gearbox. Just getting the last bit done... I've done the timing for my dad and it is spot on, just the carbs to do, but I've had 0 experience with carbs apart from tweaking the odd single one, balancing duals is a bit trickier I assume.
Attached, my dad the old-boy racer *grin*
There is a tool for this and its a simple theory from what i can remember. Something like long tubular vac tubes. I will have a lookski
There is a tool for this and its a simple theory from what i can remember. Something like long tubular vac tubes. I will have a lookski
Hmmm, I bought him a carb balancer off ebay and dropped it off one day with a note saying 'If it had FI I would do it, but carbs, here you go...'
Might look for a how to for him... but I think he is at the stage where it is the last thing to do and he would rather just get it done now, I live 2 hours away so can't just constantly drive up to him to tweak it...
Sympathise with you mate, balancing those carbs is an art form in itself. And a dying art at that. Not sure you can even get the required vacuum gauges either.
I'll have a looksee. :)
northamptonmotorsport.com looks just what you need fella. If he can do Webers he can do anything. They were always a bitch to set up. Lol.
northamptonmotorsport.com looks just what you need fella. If he can do Webers he can do anything. They were always a bitch to set up. Lol.
Cheers for that, it is a good start, I'll get him to get hold of them on tuesday, and see how it goes.. Will let you know. :thumbs:
Cheers for that, it is a good start, I'll get him to get hold of them on tuesday, and see how it goes.. Will let you know. :thumbs:
Thanks mate. They've got a good website, very informative, almost always a good sign.
Hope it turns out ok. :)
This any good?
http://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/basic4.html
This any good?
http://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/basic4.html
Sent over, cheers for this as well dude.
SUPRALOOPY
28-05-07, 11:12
You can do it by ear with a stethascope
You can do it by ear with a stethascope
Yep, it's the only way I've ever set up my twin webers along with a colour tune kit. You can fine tune with a manometer but not sure where to buy one.
I'm not looking forward to setting up the dual choke twins on the new vdub engine when I finally round to it. :)
SUPRALOOPY
01-06-07, 21:33
And I thought peeps would call me a cnut for posting that!! THANKS!!
Lovely looking car, just the kind of thing I would like as a project:)
Chris Wilson
06-06-07, 00:24
I can still do carbs properly, and have all the right gear :)
thanks for the link to northampton motorsport, I know where that is. ill give them a go for my next service or pop in and have a chat when i next have a chance see if they have done any supes before and let the locals know :)
Sounds like they know what there doing. and have a rolling road :)
I have used Northampton Motorsport in the past when i had my Lotus Esprit. They stripped, cleaned and rebuilt the carburetor. The car was perfect after that. They were very reasonable with there costs to.
I can still do carbs properly, and have all the right gear :)
I shall have a word with my dad, see if he would travel that far, but it would be an option I'd like. Cheers for that.
i see a red esprit arround northampton quite a lot. coming too and from work.
thanks for the link to northampton motorsport, I know where that is. ill give them a go for my next service or pop in and have a chat when i next have a chance see if they have done any supes before and let the locals know :)
Sounds like they know what there doing. and have a rolling road :)
Would you mind asking them for a rough cost on balancing dual carbs on a 1275cc a-series engine?
i see a red esprit arround northampton quite a lot. coming too and from work.
Mine was white and was sold to a guy in Wales about 5 years ago :)
Would you mind asking them for a rough cost on balancing dual carbs on a 1275cc a-series engine?
I will try and pop in tomorrow if i get the chance.
What make carbs are they and any other details they might want to know?
:)
Mine was white and was sold to a guy in Wales about 5 years ago :)
I will try and pop in tomorrow if i get the chance.
What make carbs are they and any other details they might want to know?
:)
SU carbs... 1 1/4 (I think), on a standard a-series 1275cc engine in a mg midget mk3 1972 RWA.
Thanks dude
dangerous brain
06-06-07, 21:25
Oh the big downfall of the twin SU. Problem with them is they need constant fettling to keep them running good. Hows about a bigger single carb?
Oh the big downfall of the twin SU. Problem with them is they need constant fettling to keep them running good. Hows about a bigger single carb?
The old man is a bit of a purist, wouldn't entertain changing them unless there was a DAMN good reason (and not being able to set them up isn't good enough in his book)... If it was me, I would have ripped them off and gone fuel injection... but parents are funny things...
dangerous brain
06-06-07, 21:48
U didnt say injection just a less complicated single carb :D
Kind of off topic I know but does anyone know the difference between IDF's & IDA's or ICT's. All I know is Weber IDA's are rare and cost a fortune lol.:)
Would you mind asking them for a rough cost on balancing dual carbs on a 1275cc a-series engine?
im not going to be able to go in for at least 3 weeks m8. best phone them
Oh the big downfall of the twin SU. Problem with them is they need constant fettling to keep them running good. Hows about a bigger single carb?
That's just not true - that's one of the typical "myths" banded around by people.
I run twin 1.5" SU's on one of my cars and have no problems with them "going out of tune" - I've never had to fiddle with them to retune once they are setup. I've been using them on the same engine for over 9 years. I have two wideband sensors installed in that car and I know 100% what the mixture should be and would definitely notice any "going out of tune".
Get yourself a synchrometer and you can set them up yourself (assuming they already have the correct and identical needles and all you want to do is balance them).
You have to take your time, slacken the linkages off, adjust each one till their sucking the same then tighten the linkages back up and check both are engaging at exactly the same time. You need to set something the same on both to start with - let's say the jet height at somewhere sensible and make it the same both sides. Then balance the airflow on both carbs, keep adjusting the idle speeds and readjusting the mixture screws to allow for more/less airflow. You'll probably find you can close the butterflies a fair bit from when you started by constant retrimming of the mixture to suit - if you have a vac gauge you'd see the engine pulling more vac at idle than when you started the tuning/balancing.
I find the large bore A series engines idle best around 12.5-12.8:1 if they've got anything hotter than a 276 cam in - anything like stoichometric is a no no! They can obviously run much leaner once on the move/cruise etc
:) It's not difficult - just take your time.
If you need to start custom profiling your own needles then I agree to a point with DB - twins become more tricky as getting two very close needles takes time. Been there and done that more times than I care to recall :)
Do you have a wideband in any of the manifold branches?
Do you have a wideband in any of the manifold branches?
Cheers for that
Just sent all of that over to the old man, hopefully he reads it and tries it before spending money, I bought him a carb balancer for his birthday, hopefully gives him incentive to try it.
I've lent him my LM-1, so he has been using that. (Lets not even go into how much bother it was trying to explain what to do with it)....
RobSheffield
07-06-07, 00:05
My dad runs twin SUs on 3 cars, 1500 and 1800 4 cylinder and 3500 V8.
All balanced by hand/ear but we are a bit far away to help :p
Chris Wilson
07-06-07, 00:37
Dandan speaks good advice :)
mikeyb10supra
07-06-07, 08:54
You can do it by ear with a stethascope
you sure can, used to do it on my old 1.9 205Gti the 45's used to sound awesome but always needed a little tweek every couple of months, the car was running to the absolute limit of what was possible power wise, I remember someone messing with the mixture screws on mine when it went in for a service and came out running like a bag of shite, took me ages to get it back to normal
You have PM Pheonix-One :)
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