Carbs From a 1970 MGB

[Kameron M]

Hello All,
A friend of mine gave me a set of SU carbs from a 1970 MGB that are in a bit better shape mechanically than my SU H2 Units. What I was wondering is if these would fit in onto the XPAG without too much trouble. I'm going to keep my carbs, probably restore them, but it would be nice to have a running motor sooner than that if these will fit right up.

Any of you know?

He said it was off of one with a 1.8 liter engine.

[stephen stierman]

They will not fit, 1 1/2 vs. 1 1/4, also not jetted correctly. Put seal kits in your old ones and they will work properly.

[Kameron M]

Okie dokie. Guess I'll give them back then.

[frenchblatter]

SU's can be renovated in a matter of hours, including replacing the throttle spindles.

However, you need to know how to do it so get a book as well as the two overhaul kits.

[Julian Evers]

The other problem with putting 1 1/2" carbs on an XPAG is that they will be too big unless you seriously uprate the engine, this effect being particularly apparent at lower revs. That is to say the air being drawn into the engine will be going too slowly to properly draw the fuel in off the bridge to give a proper mixture and, I think, the faster moving air through the 1 1/4" will set up a venturi effect to draw more air in.

I run a 1366 engine, Laystall head and high lift Crane cam (the middle one!) I still use the original well refaced carbs and the original air trunking. However I have replaced the original air filter with a K&N. When the car was set up on a rolling road the trunking helped the air flow, 2 carbs drawing through a single large hole helped keep the air moving but the air filter was a disaster, note the four holes the factory added to the bottom of the trunking, they must have realised the air filter restricted the air flow. By the end of the exercise I had 87 bhp.

Best regards

Julian