21 replies to this topic

[classicoop]

 

No, I can't see why too lean would cause backfire through carbs...timing a mile out would though. 

 

Too retard or advance?

 

I read somewhere lean causes carb back-fire.

 

Sidenote: No way is carb tuning easier than EFI tuning.

[Captain Mainwaring]

Now you're asking....but since I've been on Triumph Bonnie ignition this morning (and that's a dark art if every there was one) - I'd say you were running too retarded. Both too far advanced or retarded can cause overheating and in my case bluing of the exhausts.

You've got to bite one bullet first or you'll go around in circles. My suggestion to you is to thoroughly check the ignition system and set to standard before you play with mixture.

 

Actually once you have the knack, carb tuning is easy, I can't say easier because the only dealing I have ever had with EFI is setting TPS and throttle body, after that it tunes itself.

 

Remember, with an engine running miles to rich, you can get away with timing well away from where it should be.....oh and you mentioned about hesitation above 4500rpm - check that your fuel supply is good - you could have a low float height or blocked metering jet, filter or low pump pressure - this wouldn't stop the car guzzling fuel because it's running rich, but it could cause it to hesitate at high speed.

[classicoop]

Ignition was set and checked to be around 6deg @ 1500rpm, accdg to Haynes this is standard, but everyone keeps saying this isn't enough. So gona raise it little by little, that's if I get to remove the bolt/clamp holding the dizzy, it's on way too tight.

 

It isn't hesitation that's jumpy. It just loses all power. POWER >POWer > Power > no power.

 

by the way, what's the symptoms of a torn mechanical pump diaphragm?

[Captain Mainwaring]

it leaks fuel....... into the sump.....but maybe through the weep hole.....pump it up with the engine off and come back in an hour and see if it needs pumping again. Either that or leave the car for a while and pull the fuel feed off the carb and see if it squirts fuel in your eye - you could also make a plastic tube manometer and leave it over night or if you can find a pressure gauge and stick that in the hole. 

if it's leaking a lot, then the oil will stink of fuel....I tend to remember them outright failing rather than slow leaks.

[minidaves]

what rev counter you got fitted? not one from an injection car?

[classicoop]

it leaks fuel....... into the sump.....but maybe through the weep hole.....pump it up with the engine off and come back in an hour and see if it needs pumping again. Either that or leave the car for a while and pull the fuel feed off the carb and see if it squirts fuel in your eye - you could also make a plastic tube manometer and leave it over night or if you can find a pressure gauge and stick that in the hole. 

if it's leaking a lot, then the oil will stink of fuel....I tend to remember them outright failing rather than slow leaks.

 

The engine bay does stink of fuel lol. Oil not so sure, any used oil smells like fuel to me (even from other cars).

 

what rev counter you got fitted? not one from an injection car?

 

Smiths gauge, it free revs fine to 6k. Doubt that it's set wrong. 12k = valve float?

[minidaves]

ok just the mpi one reads wrong on a normal car