help needed fellow alfanatics :)

[alfa331.7]

today i have recieved my car back from the mechanic a mate of mine who had done his apprentiship 30 yrs ago on fiat alfa lancia

i had done to it

ignition timing set at 8degres
engine mounts
had an xhaust made up front to back 1 and 3/4 inch into 2 inch
idle adjusted
new dizzy cap and thats about it

the 33 runs on a 4 cyclinders with 180 compression each one(he done a compression test and timing is spot on he done it himself and checked it a few times

now i mentioned in earlier post my car had been running really bad well guess what still is
still knocking no power flat spots then little backfire and always does a littl back fires on first crank
he tells me my carbys need a good tune up and im getting way way to much fuel on the passanger carby  and i need a new rotor button and my alternator rconditioned as it charged only till 11.9 ?

im going nuts with this car can anyone give my good help and advice

thank you alf

[colcol]

Where do i start, get a new rotor button, check the distributor cap for burning and arcing, if in doubt, replace it, have a look at the spark plug leads in the dark, if you can see any of the leads shorting out while the motor is running, get some new leads, i once checked the original Alfa leads this way and they were putting on a light show!, on the carbs, check the needle and seat for correct sealing and check the floats for any leaks, and check the float height for correct specifications, then remove all the jets out of the carbys and blow them out, and hold them up to the light, to make sure you can see through them, some times when you blow compressed air through them, you are just moving rubbish around, so blow them out from both directions, and then check the petrol filter for being blocked up, just blow through with your mouth from the tank side of the filter, sometimes with an arrow or 'in' mark,  if it seems blocked, just replace it, Colin.

[alfa331.7]

gday colin thanks for your help

my dizzy cap is new got it when i rebuilt the heads..
spark plugs are 3 months old and my sparkys were new

but i know my rotor arm was a bit black but i lighly sanded it would having a lighly black rotor arm affect the driving

im not to good with carbys i can out them on but i wouldnt know how to tune them or take them appart bit by bit
ill think ill have to leave it to a carby whiz in sydney

colin what other issue do you think can cause this?nothing really ay mate

regards alfio

[alfa331.7]

colin could it be a worn crackshaft ? or camshaft or im thinking a coil issue seeing my coil is 15 yrs old

[colcol]

Coils either work or don't work, mine is the original coil Alfa put in in 1984, worn crankshaft will cause knocking, worn camshafts will cause lack of power, you can check the cams by removing the cam covers and sucking out the oil with a big oil gun, then have a look at the camshafts and look for roughness and metal pickup, this is not a problem area for these motors, thats if yours is a pre 87 leaded 33, after that they went to hydraulic tappets, and they had sealed cam housings, you might say that the solid lifters may need reshimming, as the valves are not closing, but you said it had good compression, i would look at the carbs, take it to an Alfa specialist who knows Weber I.D.F.'s, they would have done it a million times before, Colin.

[alfa331.7]

cheers colin

yeah i had a think and it wouldnt be the cam or crank as they were fine before hand so that cant be the problem

its a 1988 1.7 hydraulic so bit of work to take heads off and put them back on done it twice wont do it a third time haha 

i have had the heads valves valve spring hydaulic tappets all done so im 100 certain it aint them

iv booked it in on tuesday for a carby tune so im praying it just the carbys

il let you know tomorow how i go colin as im going to have a fiddle around with the car

[Frank Musco]

Take the hats off the tops of both carbys. The alloy part which connects them to the air box.

Start the car and let it warm up until the idle settles.

Look down into the carbys. BE CAREFUL. I don't want it to backfire into your face, so keep your distance!

You want to find that the throttle valves look dry while the engine is operating at idle speed (the part that opens and lets the air in).

If you have backfire, you should find that one carby looks wet from excessive fuel being draw into the venturi/throats. You may find only one venturi wet.
 
Both venturi wet  in one carby could be a worn needle and seat, or bad float adjustment.
Only one venturi wet per carby could be a bad seal around the accelerator pump jet. Could be both though, usually happens when car has been sitting for a long time and the old o-ring seals dry up.

These problems can cause backfire and flat spotting because the cylinder will be getting too much fuel and momentarily putting the spark out.

You may also have a rip in the accelerator pump diaphram. This also causes flat spotting from not enough fuel delivered. Usually you will find petrol leaking from the outside of the carbys, from the pump cover. The part with four screws and looks square on the lower half, center of the carby.

Could also be very poor mixture adjustment. If your confident, with the engine off, gently screw the mixture screws in until they stop, then accurately give them 2 and a half turns out and start the car. Before you do this, get a piece of paper and write down how many turns each mixture screw is turned until it stops, so you can return them to the same position before you started if things go wrong. Since the heads have been done, and the cams are good and so on, you should find they are very close to each other with respect to number of turns. Once you've done this they should need less than half a turn to get a good mixture. Do this very slowly and listen very carefully, take note of engine speed and listen for the 'sweet spot'. One way the engine slows, then the other way and the engine goes too fast and you should note the engine is not smooth.

Not to sure what you mean by knocking either?
Do you mean tapping from a bad lifter?  OR is it just a worn piston, so when it warms up it goes away? OR is it louder and consistent, and every time you give it a rev it gets louder like a crankshaft big end bearing noise? OR is it pinging from a cylinder leaning out? OR...

Also, is the cam timing correct?  Sounds a bit like the car had these problems before the top end was done, and that job made no difference?