hey all

 

ok i've just put a dellorto 40 sidedraft on and its backfiring through the rear barrel.also the gasket of the rear two cylinder is soaked with fuel as well.

 

now the engine seemed to be running fine with the stock carby on it, a little rough at idle, but i put that down to having a stock carby on a sligtly worked 5K. putting this new carby on, i don't know if the engine is now showing the symptons because of the sidedraft and it now has two barrels so u can see that its got a problem, or there is something wrong with the carby.

 

from what i know, i'm guessing its the engine, however i don't get why its running shit one one of the last two cylinders and not all of them. if it was a timing problem, i would of said all cyclinders would be firing in correct!

 

 

hope this makes sence, any help would be great, i'm nearly ready to just sell the whole project!

 

cheers

 

Steve

It could be a number of problems.

 

1. Timing.

2. Carby tuning.

3. Motor needing rebuild/fixing

4. Filters.

5. Something else!

 

I suggest you take it to someone with experience with these sort of motors/problems and/or a mechanic and

get them to give it a diagnosis.

 

ps. Fuel shouldn't be running through the gasket on the rear 2 cylinders..... Replace!

Edited July 26, 200917 yr by seabiscuit

Backfiring through the carb usually signifies running lean. Is the carby rebuilt, jetted correctly etc?

 

I'd get it to a dyno tuner. It will be the money well spent.

Did you replace the manifold gasket?

or the "O" rings between the carbys and the manifold?

 

could be an air leak

Edited July 29, 200917 yr by TRD ke70

yeh i think i've narrowed it down to way to much fuel, i took the carby off after a run, and fuel was just sitting in the manifold. plus i could hear it sizerlying after i turned the car off. so i will play with the float level. still don't know why it blows back through the carby sometimes tho!

 

however, the vacum in the distributer block is going syco! that little adjusting knob which is covered by a see through plastic case, that knob is going in and out and makeing a pretty loud tapping noise! This has got me pretty stumped!! any ideas?

however, the vacum in the distributer block is going syco! that little adjusting knob which is covered by a see through plastic case, that knob is going in and out and makeing a pretty loud tapping noise! This has got me pretty stumped!! any ideas?

 

you have the vacuum advance hooked up?, Dellorto's don't have a vacuum advance tube, disconnect it!!!

this could be your problem, the vacuum advance is changing the timing at idle, the vacuum advance should only work under hi vacuum, lite throttle conditions, not at idle.