MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - Marvel's mystery Oil

I've seen Marvel's mystery oil recommended for dash pots on several occassions, but when I go to the store Marvel's Mystery Oil has several different products.

Which specific product should I be using.

Thanks
tysen

engine oil, which then would have been straight thirty weight if memory serves.
BOL,
Doug
D Sjostrom

http://store1.yimg.com/I/rodi_1865_17736671
Jeff Schultz

Jeff,

That's exactly what freaked me out: it says "add to gas and oil"

Makes me think its some sorta detergent or something
Tysen

Tysen. Marvel's has some strong detergents in it, as does ATF. For the dashpots, straight 20 or 30 weight works just fine. On my 68BGT, I use the Castrol 20W50 with no problems noted over many years. In Wyoming winters, we used 20W20 in the dashpots. In Florida summers straight 30 weight worked fine. In either case, the same oil was used year round on cars that were daily drivers. I am not convinced that the exact oil, as long as it is not too heavy, makes any real difference and any of these should work fine for you. ATF and Marvels are about a 10 weight oil and should allow the pistons to rise slightly faster than a heavier oil. But, if the ignition system is in good order (main cause of "carb problems") and the carbs are needled correctly and adjusted and balanced, anything up to 30 weight should do fine.

Les
Les Bengtson

All,
Had a real educational summer when I installed a rich /lean oxygen sensor gage to enable needle selection and fine tuning my 1800, Sierra, MGA exhaust & Aircleaner set-up. This enabled selection of better needles plus showed me clearly that going from 20W to 30W improved a lean acceleration to slightly rich.

It would appear that adjusting damper fluid viscosity is the equivalent of setting the accellerator pump on a conventional carb. Thicker to richen, thinner to lean it out with the added advantage of self adjustment as the damper oil warms with engine & ambient temperature.
Doug
D Sjostrom

Doug, Nice to know that the theory and description of how the SU's are supposed to work are verified by 1990's technology.

The theory is that the damper fluid causes the air speed to increase across the jet causing more gas to be pulled from the jet, i.e. a richer mixture. This is a momentary situation as shortly thereafter, as determined by the viscosity of the fluid, the piston rises, lowering the rate of airspeed across the jet.

Chuck
Chuck Schaefer

This thread was discussed between 14/10/2005 and 15/10/2005

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.