81 Spider Firing Issue - Alfa Romeo Bulletin Board & Forums
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post #1 of 5 (permalink) Old 05-13-2018, 07:20 AM Thread Starter
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81 Spider Firing Issue

Hello,

So I've been getting mixed answers as to what the proper firing order for an 81 Spider 2000 (dual Solex carbs) is. I've attached an image of my engine bay for reference. I believe, according to the manual, that the firing order on the engine is 1-3-4-2, from the front side (radiator) going back. I also believe that the order on the distributor cap should be A=1, B=2, C=3, D=4, going clockwise.

The problem is when I hook it up in this order and try to start the car I hear low popping noises in the exhaust and the car does not start. Also, when I give it a bit of gas while starting, higher popping noises come from the carb intakes and white smoke comes out of them (this I suspect is because the spark plug is sparking while the intake valve is open, but I do not know for sure).

Has anyone else had similar issues to this, or know if the firing orders are correct?


-Nick
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1981 Alfa Romeo Spider (Dual Solex C40 ADDHE)
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post #2 of 5 (permalink) Old 05-13-2018, 07:37 AM
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The cylinder at the front - closest to the radiator is #1 - moving back they are numbered in order: 1, 2, 3, 4

The distributor rotor turns clockwise. By convention location A in your picture is for #1 (but it is possible for it to be any of the other positions if the drive gear was not oriented correctly when the engine was assembled). Best is to confirm that #1 is at TDC on compression (remember that is a four cycle engine he piston goes to TDC twice in one complete cycle). Either remove the cam cover and turn the engine until the #1 cylinder's cam lobes are facing away from each other -or- remove the spark plug and turn the engine in the forwards direction (put in 4th gear and roll the car) with your finger over the spark plug hole. As the piston comes up on its compression stroke your finger will get pushed out. Move it a little more until the P mark on the crank shaft pulley aligns with the pointer. #1 is now at TDC on compression. Note where the rotor is aimed. The #1 spark plug wire must attach to the cap there. The remainder are connected in the firing order (1-3-4-2) going clockwise around the cap.

If position A is correct for #1 then B= 3, C = 4, D = 2.
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- - Eric
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~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
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Last edited by ghnl; 05-13-2018 at 07:44 AM. Reason: add photo of correct cylinder numbering
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post #3 of 5 (permalink) Old 05-13-2018, 07:43 AM
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Quote:
Originally Posted by alfaspidernick
Has anyone else had similar issues to this, or know if the firing orders are correct?
You´re asking for advice not knowing what had happened in the last 37 yrs to your motor.

If somebody had the head off and didn´t install cams like before it might be 180° wrong at the dizzy rotor.

If somebody took off the oil pump and did refit it by chance, it might be totally different.

But it´s quite easy to check:

- take off dizzy cap
- take out plugs
- take off valve cover (or you´re able to spot both valves overlapping at CYL. 4 (!) when cylinders 1+4 are @ TDC - it´s possible !)
If you aren´t able to spot overlap @ C4:
- with 5th gear engaged, push the car forward until 1st cyl. cam lobes point BOTH OUTWARDS @ TDC marking. This position indicates Cyl. 1 at firing order NOW - also at your dizzy rotor !

Now check out position of dizzy rotor in relation to cap; you´ll need to regroup the leads starting with C1 clockwise 1-3-4-2.

Then refit all bits and start your car.

Last edited by hunttheshunt; 05-20-2018 at 04:59 AM.
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post #4 of 5 (permalink) Old 05-14-2018, 07:25 PM Thread Starter
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Thanks for the responses and tips Eric and hunttheshunt. You both hit it on the mark exactly. It turns out the correct order on my distributor cap was 180 degrees off of what it should be (for me it's A=4, B=2, C=1, D=3). She started up right away in that order! So yes, I'm guessing at some point in the car's history someone didn't put something back correctly. What I ended up doing was wiring up the "correct" order, then try to start the car. If it didn't work, rotate the configuration on the distributor cap by 90 degrees clockwise.
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Nick
1981 Alfa Romeo Spider (Dual Solex C40 ADDHE)
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post #5 of 5 (permalink) Old 05-14-2018, 07:35 PM
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My guess is about half the Alfa's out there have their distributors 180 degrees 'off'. As long as you get the firing order correct it'll run fine.
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- - Eric
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~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
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