Setting V6 ignition timing - Alfa Romeo Bulletin Board & Forums
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post #1 of 19 (permalink) Old 04-30-2018, 07:10 AM Thread Starter
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Setting V6 ignition timing

I'm curious to read how folks on the AlfaBB set their ignition timing. 3.0L 10:1 Verde with C&B road medium cams, so a mildly upgraded engine.

The manual states that when installing a distributor, one should align the rotor with the marking on the distributor while the front cover indicator points to the crankshaft hub "F" marking. Then, for the 3.0L, the ignition advance is listed at 7 degrees +/- 1 degree BTDC. This should be conducted on warm engine, with vacuum advance hose unplugged (according to the book. I have also heard that it should instead be pinched with clamp), and the idle at 850RPM, which is adjustable on the intake manifold.

When checking with timing light, I dial in 7 degrees of advance, and check static timing as seen above by pointing light at hub. Should I base off of the "P" or "F" mark when setting static timing?

Any recommendations outside of this? I know that some folks deviate from the prescribed 7 degrees. I'm in the process of dialing in timing and would like to get some confirmation (or correction) on my process, as well as hear advice from others.

Thanks!

Graham
88 Milano Verde, 13 500 Abarth, 04 Used Maserati Coupe GT
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post #2 of 19 (permalink) Old 04-30-2018, 08:02 AM
But Mad North-Northwest
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The F mark is at 7 degrees, the P mark is TDC. To set your car to stock you just set your timing light to zero advance and adjust to the F mark. Alternatively you could dial in 7 degrees on your timing light and time to the P mark...should get you to exactly the same place.

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post #3 of 19 (permalink) Old 04-30-2018, 08:19 AM
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Agree with Tom. You should pinch the vac hose when you disconnect it. Both my distributors have failed vac capsules so in my case it was never necessary to disconnect it.

Ed Prytherch
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post #4 of 19 (permalink) Old 04-30-2018, 09:34 AM
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I think that bit in the manual about the vacuum line is a holdover from the older V6 cars that had the vacuum hose connected to manifold vacuum. On the Milano they switched to port vacuum, so there is no vacuum on that line with the throttle at idle (you should see vacuum on the line as soon as you open the throttle plate.)

So on my old Milano 2.5, at least, there was no need to disconnect or pinch the line or anything to set static timing at idle.

Tom

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post #5 of 19 (permalink) Old 04-30-2018, 11:15 AM Thread Starter
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Thanks for the input, Tom and Ed!

On stock L-jet, are people generally satisfied with setting to 7 degrees static? Any success in deviating from that?

Looks like the BB member adjusted springs in distributor to increase static advance without going too far on max/vacuum advance: http://www.alfabb.com/bb/forums/alfe...ml#post4822058

Graham
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post #6 of 19 (permalink) Old 04-30-2018, 11:53 AM
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Quote:
I think that bit in the manual about the vacuum line is a holdover from the older V6 cars that had the vacuum hose connected to manifold vacuum. On the Milano they switched to port vacuum, so there is no vacuum on that line with the throttle at idle (you should see vacuum on the line as soon as you open the throttle plate.)
That shows how long I have been in Megasquirt mode

The advance curve is not controlled by the distributor but by the advance computer so you cannot change it. You can shift the whole curve by rotating the distributor. I don't remember what the max advance is but I can tell you that on a dyno my 3L motor with "S" pistons made max power at 34 degrees. A lower compression motor might need a shade more. You should not run into starting problems if you keep the static below about 12 degrees.

Ed Prytherch
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post #7 of 19 (permalink) Old 04-30-2018, 12:18 PM Thread Starter
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Originally Posted by alfaparticle View Post
That shows how long I have been in Megasquirt mode

The advance curve is not controlled by the distributor but by the advance computer so you cannot change it. You can shift the whole curve by rotating the distributor. I don't remember what the max advance is but I can tell you that on a dyno my 3L motor with "S" pistons made max power at 34 degrees. A lower compression motor might need a shade more. You should not run into starting problems if you keep the static below about 12 degrees.
Good to know with the 34 degrees - thanks for divulging . I'm running 10.1 i.e. "S" pistons.

I guess adjusting springs 'inside the distributor' was referring to adjusting the springs in vacuum advance bit so that the signal to the ignition computer is altered.

Based on the ignition advance curve, looks like static advance would be 34-(12+/-2) = 10+/-4 degrees. Add in 12 degree static constraint and that's 10+2/-4 degrees. I'll do some acceleration runs and see what seems to stick



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post #8 of 19 (permalink) Old 04-30-2018, 06:27 PM
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I think that if you disconnect the vacuum hose from the distributor you can measure the max advance by using an adjustable strobe on the P mark with the engine at 5000 rpm. If for example it is 30 degrees when your static is 7 degrees then you would move the static to 11 to get 34 degrees max advance.
Also, the manual says disconnect the vacuum hose to check the static timing.

Ed Prytherch
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Last edited by alfaparticle; 04-30-2018 at 06:29 PM.
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post #9 of 19 (permalink) Old 04-30-2018, 07:13 PM
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Originally Posted by fourmotioneer View Post
On stock L-jet, are people generally satisfied with setting to 7 degrees static? Any success in deviating from that?
I find that you will get noticeably better throttle response by bumping the timing a few degrees. At high altitude we use 12 degrees, but at sea level I would gradually work up from the stock 7 degrees and make sure you don't get any pinging.

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post #10 of 19 (permalink) Old 02-22-2019, 05:33 PM
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I find that you will get noticeably better throttle response by bumping the timing a few degrees. At high altitude we use 12 degrees, but at sea level I would gradually work up from the stock 7 degrees and make sure you don't get any pinging.
How about the stock 2.5 V6? Does it benefit from slight advance of the timing from stock?

I just checked and adjusted my timing in preparation of a smog test and I found the timing to be too advanced so I dialed it back to 7 degrees and now the car seems a little less happy to rev. I think I'll be advancing again once it passes smog but do you have any suggestions for optimal timing for this engine?

Thanks and thanks, Joe, for the recent quick shipping of my parts....

bob

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post #11 of 19 (permalink) Old 02-22-2019, 05:47 PM
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My 3L motor has S pistons and it made best power with 34 degrees max advance.

Ed Prytherch
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A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
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post #12 of 19 (permalink) Old 02-22-2019, 06:08 PM
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Quote:
Originally Posted by superloaf View Post
How about the stock 2.5 V6? Does it benefit from slight advance of the timing from stock?

I just checked and adjusted my timing in preparation of a smog test and I found the timing to be too advanced so I dialed it back to 7 degrees and now the car seems a little less happy to rev. I think I'll be advancing again once it passes smog but do you have any suggestions for optimal timing for this engine?
Stock advance on the 2.5 Milano is 2 degrees, not 7. Look for the mark on the pulley. If you set it to 7 you won't pass the smog timing check (assuming they do it.)

My old Milano 2.5 was definitely a bit more peppy at 7 static. I didn't go higher than that as I didn't want to risk pinging.

Tom

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post #13 of 19 (permalink) Old 02-22-2019, 06:11 PM
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Also, if it was that far advanced I'd disconnect the distributor vacuum line and see if the timing changes (it shouldn't on an '87 Milano.) If it does it's possible someone adjusted the idle with the throttle plate rather than the idle bypass, such that you're getting ported vacuum to the distributor at idle (which, again, you shouldn't.) If that's the case you've seriously retarded your static timing, which would explain the sluggishness.

Just trying to think of reasons it would be that far advanced at idle.

Tom

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post #14 of 19 (permalink) Old 02-22-2019, 11:44 PM
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Here's an interesting discussion with some useful info about ignition timing and ported vs. manifold vacuum.

https://bangshift.com/forum/forum/ba...vacuum-advance

My 3.0 with standard compression and S like cams is now set at 11BTDC at 900rpm, vacuum off. Also, moved distributor to manifold vacuum resulting in much smoother idle and responsiveness.
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post #15 of 19 (permalink) Old 03-11-2019, 01:30 PM
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Thanks for the additional timing info and thanks for the 2 degree correction. I readjusted my timing to the correct 2 BTDC and the car passed smog easily. I think i'll probably bump it up a bit as it seemed a little peppier with the advanced timing before i adjusted it. At least i think it did....Not really sure but I'll give it a try and see what happens....

bob

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