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MG Midget and Sprite Technical - Fuel and vent line connections

I am helping a friend with his 1962 Sprite. The Carbs have been changed out for what I believe are H2 AUD549's. No tags. I think they were used on the 1972 midgets. I need a photo from a 72 that would show how the fuel and vent lines were connected. Just want to make sure the lines are connected to the correct ports before going any further.
Thanks
B Stone

You need to bear in mind that even if the Midgets were 100% factory original there were many hundreds of variations on the car models between 1962 and 1972 and that is without the variations for different markets and 50+ years of owners' changes.

The venting for 62 was different to 72.

The fact that the carbs may be later models suggests IF the engine is 62 that the venting may be mix and match.

What else is non-standard on the carbs, their filters, and the engine.

Below is a 72-ish set up - hose from front chain canister to y-piece to carbs, plastic vented and filtered oil filler cap - (no valve, or hose to filter housing or rocker cover).

Chrome bling oil filler caps don't breathe as well as the original plastic.

Dissy vacuum behind/side of front carb, choke cable at rear carb, petrol (gas) to front carb then on to rear carb.

If you're able to put up a good photo of your friend's set up then others may be able to point out if there are other anomalies you need to take into consideration.




Nigel Atkins

Found a photo showing the fuel line connection port ,the connecting port to both carbs and the vent port that would normally go to the charcoal canister. Thanks for the your input.
B Stone

There you go charcoal canister - a variation, I did consider this but didn't think they were on 62 cars(?).

There are (John Twist) University Motors videos on YouTube, the relevant Driver's Handbook or factory Workshop Manual that will show the standard set-ups with charcoal filters/smog/emmissions.

Don't assume how the current set up is fitted is correct or fully functioning - although it might be.

Nigel Atkins

I looked at John's Videos didn't find one that showed this. Right, not correct or fully functional, but workable. Just wanted to make sure fuel line wasn't connected to vent etc.
B Stone

Fair enough.

Sorry I was wrong, just had a quick look and the JT vids refer to Bs and 1500s.

Pages 44-49 here might help - http://www.spridgetguru.com/DriversHandbooks/AKD7937.pdf
Nigel Atkins

Thanks for the Handbook link. That's a big help.My books are packed after a recent move. Didn't expect to be working on this car.
B Stone

No problem, I'm a big promoter of the Driver's Handbooks. :)

You might also find this page useful until you can unpack the more convenient, useable and reliable printed paper copies, it has DHs and factory Workshop Manuals to cover the years. -
http://www.spridgetguru.com/TchIndx18.html
Nigel Atkins

Have everything connected to the right ports. set idle screws in 1.5 turns, jets down two turns. car runs slow and then fast. Was able to get my air flow meter on. The back carb. It is in the middle of scale, of course it want's to pick up speed if I leave it over the intake for more than a second. The front carb. Airflow maxed out and very sensitive to speeding with air flow meter on, even when I back idle screw out.So I assume a vacuum leak with the front although everything looks good. These carbs. Do have the pop-off valves on the butterflies and the butterflies seem to be closing . I know some comments suggest timing issues can cause the fast and erractic idle. Haven't checked timing ( so darn hard to see) Wouldn't think it would run if it was too far off. What direction should I go other than the nearest bar.
B Stone

Car will run with lots of faults and missets, (even leads wrong).

As it's at least idling - if you've not already done so very recently, I'd go from the start, check the tappets, CB points, (rotor arm, dissy cap, HT lead set), plugs, timing and carbs last.

More technical stuff is well beyond me - other than, ALWAYS test your test equipment before conducting each test with it, and I think from what I've read valves on flies can be a PITA.

Some timing guns seem to be erratic and the bottom timing marks can be a pain so if you can accurately set your own above that might help.

I don't think you get the car fully set until it has been run regularly over reasonable length journeys so getting it to a reasonable running state first is acceptable to proceed from.
Nigel Atkins

I would check there are no air leaks. Is the manifold gasket in good shape? are all the inlet manifold nuts up tight. Are all the carb gaskets ok (they generally are)
What is the condition of the carbs, are the throttle spindles worn? I don't like the pop off valves as the are just another source of a problem but they closed and not leaking air.
yes check the rocker clearances are ok and the valves are closing. Have you done a compression check?
The other point is the carb needle. The '62 car has a 948cc engine but the '72 car is 1275cc. The needles are different so have they been changed to the correct ones?

Bob Beaumont

This thread was discussed between 17/08/2019 and 22/08/2019

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