How to tune a 2lt

[joestram]

Hi All,

I have tried and tried again to tune my engine with no success.

I feel like groundhog day every time I try.

Are there any mechanics that do home visits or any courses I can do on how to tune a carburettor engine?

I am also willing to pay someone to come and teach me whilst they tune my car.

The car has had some work done to the engine so I am wondering if this is making it more difficult.

Thanks

Joe

[carlo rossi]

take it to benincas dyno
they know alfas back to front
the basics are once you think you have no leaks air or fuel
screw one of your idle (mixture)screws gently in ( clockwise ) and count the turns
once you have established that screw it out again to the same number
do the same to the other 3 so they are all the equal to the first one
You have established a base
start the engine with a higher than standard idle 1200rpm
get a piece of tube put one end in your ear the other near the opening of number 2
then compare to number 3
adjust the central balance screw ( on the throttle ) until they sound the same
now you have balanced carbs
now adjust each idle screw 1/4 turn anti clock wise to each one whilst running
did the idle go up or down
if it went up go again if it went down turn 1/4 turn the opposite way and then 1/4 again ( clockwise)you are now 1/4 turn clockwise from start
until you get the highest idle then turn them 1/4 turn Anticlockwise so that it doesnt run too lean
so play around equally until you find the best idle
then adjust you idle screw down to 800rpm
carbys 101
this assumes it was going originally

[105greg]

I have had success with a device called a colour tune. Google it they are made in England and are relatively cheap.  The idea behind it is you screw the device into the plug and when the colour turns blue the mixtures are correct.   Anyway google it to find out more.  Cheers. 


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[bonno]

Hi Joe
Check that it's not leaking at carburettor mounting blocks , ie; not split or damaged. If, OK adjust carburettors as previously described by Carlo above. A tool to balance carbs is available through e-bay, if the screwdriver, tube and sound method is not your cup of tea.   

[Alfapride]

I saw your previous posts are you sure you have 45mm carbs? 40mm original are best on this engine this could be a situation where you have he wrong pair fitted incorrectly jetted my advice would be to go back to stock carbs and have tuned properly and you'll have no dramas after that

[joestram]

Hi All,

Thanks so much for your feedback!

Carlo - I have no problem taking it to someone and I have heard good things about Beninca, I would just like to learn how to do it and I won't be able to learn if I take it there.

I have tried a few different methods with no success and I am not sure if there is something wrong with the timing or something else.

105greg - Thanks, I'll check that out.

Thanks Bonno - I'll re-check the gaskets etc.

Alfapride - Thanks for remembering. I think they are 40's, however, they have been rejetted or something.

Apparently the car has some PACE street cams and has been re-jetted with a electronic fuel pump.

Not quite sure how that effects tuning, however, I have never had it running smooth in 2 years!

[bonno]

Joe
Thanks for the acknowledgment  and would be of interest/helpful to forum members on the final outcome.

Cheers
bonno

[Duk]

It would be interesting to use a K type thermo couple with a suitable multimeter to measure the temperature of the exhaust runners near the head and see how much of an effect changing the idle mixture screws has on exhaust pipe runner temperatures.
Probably not as accurate as having sensors inside the pipe and directly measuring the gas temperatures and the changes would be slower to show as the pipes would have to heat up or cool down with the different gas temperatures as a result of mixture changes, but it should give some decent information about individual cylinder tuning.

[bonno]

Hi fellow Alfisti's
You can buy a unit for balancing multiple carburettors on e-bay for under $100AUD.  I am still not convinced that the use of carburettor balancer will fix the problem, ie; process of elimination of possible causes identified in the message thread.
Regards
bonno

[carlo rossi]

No it may no entirely fix it
but you have to reduce the variables
once you have acheived this
then you adjust the idles as previously described
then if youi have misses around 2000 to 3000 we can fix this
tell me what jets emulsion idles are in it
what chokes and is it 40mm dellortos
then take the cam cover off and tell me whats the numbers on the cams
then we can tune it right

[Duk]

Wide band air/fuel ratio meters are well priced now, so I'd suggest getting 1, installing it and monitoring it during a test drive or 12.

Also make sure that the advance mechanism in the distributor is free to move and the ignition timing is correct.

Welcome to modifed carby cars............. Where, apparently, they are easy to tune, but you don't actually have the means or the huge selection of parts to actually tune them.
Or their ignition timing.

[Mick A]

Hi Joe, I'm surprised nobody has suggested this yet.

First thing to do would be to do a compression and leak down test on the engine.

Could possibly have a burnt out valve, or even a broken piston or piston ring. Will make it impossible to tune if this happens to be the case.

Mick.

[bonno]

Hi fellow Alfistis
I think Joe has a lot of work to do, to establish the root cause of the tuning problem initially described. The difficulty I see is the lack of detail with what the car is doing at idle and whilst being driven, ie; rough idling, lack of power through the rev range, misfire, etc, etc. Sure the condition of engine should be the first thing of the fault finding process and all the others identified in the thread would then follow by the process of elimination. Like a former Prime Minister once quoted "Life wasn't meant to be easy".

cheers
bonno

[joestram]

Hi all, thanks for all the replies and feedback. I finally had some time to inspect the car and have some more info. Here is what I found:
Choke emultion 7482.3
Choke jet 80
Main emultion 7772.8
Main jet 145
Idle jet 55
Cams: Pace 2229
While I was checking things I noticed the top of the main and idle emulation tubes were very black which didn't seem normal. I will post some pictures. Thanks guys


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[joestram]

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