Whether it's my "ignorance is bliss" nose or not, whenever friends ride in my '70 Austin they point out how bad the fumes are, and slide the windows open. OK, I admit there are fumes to be smelled (compared to a newer "regular" car), but is this somewhat normal or might there be something wrong? It has a pieced-together RC40 muffler that's a bit loud. Would replacing it help?

 

gasoline and exhaust don't smell alike (unless you are running SUPER rich)

if the smell IS gas then a leak is VERY suspect and since the carb and fuel lines tend to be VERY close to the HOT exhaust I'd be looking.

places I'd start:

- if you still have a mechanical fuel pump mounted to the block they will fail around the seam. Some models come apart & there is a rebuilt kit ... others are sealed. It is probably easier to just replace the pump either way altho the clearance to get the bolts out is TIGHT unless you pull the exhaust manifold first. I did mine, but it took buying 3 different wrenches outside of the ones I already owned!

- check all the fuel lines ... the rubber ones and their clamps. You COULD be on originals; cracked and leaking.

- if the carb seals are failing you could have drips there . . .

when everything is 'right' in my 79, 1275, hif-6 SU / K&N, LCB and Play Mini DTM ... I get ZERO fumes ... NOW ... when I first got it the fuel system leaked fm the 3 sources I described. First night I parked it in the garage, when I went out in the morning I was worried the fumes would cause the place to blow up!!!!

IF your exhaust smells strongly of fuel ... you need a major tune . . .

 

If the pump is good you might also have a stuck float on the carb. The next time you experience the smell give the float bowl a light rap with the handle end of a screwdriver. If the smell stops you may have found the culprit. Also a '70 will probably have a vent line on the gas tank. Check to see if it's secure and the tubing goes through the boot floor. Good luck!

 

good point and actually the entire piston could be stuck in the pot

when's the last time you checked the oil level IN THE CARB?????

(u know what I'm talking about don't you??)

There is a button on the SU carb that allows you to bounce the piston and ensure it is moving freely. I find I need to remove the entire piston housing and clean things up once a year; even using quality fuel and an ethanol compensation additive, the surfaces develop a shellac like build up which can make the piston hang up ... easily cleaned with a little carb cleaner.

Need detail? PM me.

 

I would also check that the vent tube on the gas tank has not come off or is seeping fumes into the boot.

 

Thanks for the suggestions. Being a newbie about this vehicle means I'll need to get together with someone local to work through your ideas with. I'll post what I find.