Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing SU carburetor advice needed

Interesting in that a MGBGT I once owned had warn spindle shafts. This manifested itself in a high idle rpm that could not be adjusted. Diagnosis was a drop of oil on the shafts. Rpm would then drop & become adjustable, but only for about 30 seconds. Then revs would increase again to around 1200 rpm.

This is a link to their website ...

They are in Salisbury, UK and before becoming owners of the SU, AMAL and other British Carburetors were a Morgan dealer!
The owner, John Burnett, has retired but the owners son has taken over and he is a total petrol head!

New SUs are now made using modern materials and CNC machining, they are alcohol in fuel proof and polished look fantastic. Chromed dashpots are available...

Contact them for advice, but in general once the body of an old carb is worn to the point that the butterfly spindle needs bushing other internal parts and passageways will be worn and the thing needs replacing, not repairing.

I'd get in touch with Joe Curto

and I would stay as far away from Dana Britton as possible (SUCARB.com)

Spindle wear is a common problem on SUs. You used to be able to buy a an oversize shaft which could be fitted by reaming the holes. But in my experience most people opted for buying an exchange unit.

It turns out that .006" clearance on the throttle shaft isn't much of a problem. I learned a lot about SU's, probably fixed some minor carburation problems but didn't solve my poor running at low speed. I started back at square one yesterday and replaced my pertronix ignition with the original breaker points. With the original point installed I couldn't get any spark at all. After a little diagnostic work, I concluded that I had a bad condensor coil. Replaced the condesor, set the timing, and the engine runs like a champ.

The new Pertronix III unit doesn't work for me. It's great for starting, but the car runs very poorly at low speeds. I'm sticking with points igntion for now.

When you ran your Pertronix III did you upgrade your distributor wires to something that blocks electromagnetic interference? If not, that may have been the trouble.

I too have given up on Pertronix. Not because it doesn't work, but I have had trouble diagnosing. With points it is bloody simple. I used to use a CD ignition MSD 6A. However now I have replaced the MSD unit with a Winterburn CD. Designed & Made by a Morgan Owner in Ontario, Canada. Seems to do a better job than the MSD 6A. Starting is a WHIZ! Plugs look like they should. Nut Brown. I am using MSD 7.5mm ignition wire. Not sure if I need to but that is what I am using. As this is a TR engine I have stuck with Champion Spark Plugs. BTW: This is a '63 +4-4Str. It is the Morgan I drove to Key West from Seattle and back. Also My choice for shipping it to the UK to enjoy the 50th of LeMans and the 40th Party at Assen, Holland then back to Boston for a drive across the U.S. to Seattle. It will also be My choice for a trip to New York in the Fall as well as a "Pub Crawl" in Maryland, and Virginia then back thru Memphis, Tenn., and Seattle. These long trips are not trouble free, as this Morgan is 55 years old. But there are a lot of modifications to make it reliable and comfortable. No it does not have air conditioning other than a Roadster. Also the engine is stock. No special cam etc. I have learned by lesson on engine modifications.

Button
Seattle

I have a Winterburn too in my old 4/4. Button, have you registered any change in acceleration or petrol (gas) consumption? In my car it made no difference apart from the much better starting.

Frank

No. But after pulling the spark plugs I noticed they were the color they should be and clean. Nut Brown. As for performance improvement, other than quick starting and smoother engine running, I have not enough miles on it to judge.

Button
Seattle

I did change out the plug wires to a suppression type. Pertronix Pertronix was pretty clear on the head to use suppression wires. While I've given up on the Pertronixunit for now their customer service is excellent. I've had this unit sitting on the shelf for six months and they offered diagnose it on the distributor (I can't part with it over the summer), replace, or refund it. I asked them to diagnose my parts, and send a second generation unit as a replacement.

Do you happen to remember who the gentleman is who makes the Winterburn CDI? I remember Richard Winterburn as a long time Morgan owner but believe he passed away a few years ago.