No power with secondary

[Shaun1305]

Got my ignition problems figured out....mostly. The car runs fantastic under 1/2 throttle. As soon as the secondary opens up it's got nothing. Could this be timing or carb related.....either adjustable screws or a plugged orifice? I just had the entire thing off the car and blew out every port I could see. 1978 1.8L, electronic ignition, free flow filter, all smog removed

[18Fiatsandcounting]

Which carb do you have? 32 ADFA or some version of that?

When you say "it's got nothing", do you mean the engine power just tails off, it won't rev, or ?

-Bryan

[Shaun1305]

32afda no power, it will rev but barely. Feels like no power behind it. I blocked off the 3 lower ports I believe....

[18Fiatsandcounting]

With the car in neutral, the engine should be able to rev all the way to redline on just the primary barrel of the carb. If it can't, it sounds like one of several possibilities (in order of likelihood):

1) Ignition timing is wrong. Do you have a vacuum advance for the distributor, and did that vacuum line get disconnected?
2) Big vacuum leak somewhere.
3) Plugged up carburetor (jets, fuel filter, etc.)
4) Plugged catalytic converter (but only if you have one of course). Or simply a plugged exhaust system.

-Bryan

[Shaun1305]

Bryan,

Let me first thank you for being so responsive. The distributor on this car doesn't have a vacuum advance. Maybe some years didn't have this? Or maybe someone in the course of owning this particular car swapped it out incorrectly? I'll check timing. Should I check this weighted timing advance I keep reading about? I'll check for a vacuum leak in the meantime.

Thank you!!!

[18Fiatsandcounting]

You're welcome. Not all spiders had a vacuum advance, so yours might not have one. Regardless, if you put a timing light on the car, the advance at idle should be around 0 to 10 degrees BTDC, and as you rev the engine, it should increase to a total of somewhere around 35 degrees. I know there are no marks for these higher values, so just estimate as best you can. At 3000 rpm, the advance should stop increasing and level off, so no need to go any higher. Unless it continues to advance in which case you've got a different problem.

While you have your timing light out, I'd also put the pickup on the single wire from the coil to the distributor center. You should get an almost continuous set of flashes, and as you rev the engine, look to see that the flashes are steady with no gaps or "blank spots". Up and down the rpm range.

Also, with the car in neutral, slowly increase the revs just on the primary barrel of the carb. Does it seem smooth, or does it seem to falter once you get to higher rpms? Now open the throttle quickly (from idle) so that both barrels are all the way open but the engine speed is still low. Does the engine speed increase rapidly, or does it seem to bog or stall out immediately after you open the throttle? If the latter happens, that would seem to indicate a fuel issue as the engine speed hasn't increased yet at that point for the ignition timing to have much effect. If it does bog down, it could be that secondary butterfly valve is opening to let plenty of air in but no fuel is entering through that circuit so the engine goes way lean and stalls out.

Lots of questions, sorry about that!

-Bryan

[18Fiatsandcounting]

PS:
https://motofaction.org/mechanical-101/ ... main-jets/
I know it's not a great picture, but take a look at the top photo. See those 2 strut looking things going diagonally across the primary and secondary barrels? They can be taken out, and they can be installed backwards so that no fuel can flow into the barrel if they are. Sometimes they are staked in, but you can shoot carb cleaner or the like into the main fuel jet and you should see it come out of both the air corrector jet (cover your eyes) and out of these "strut like things" at the bottom.

Anyway, check and see that the secondary one isn't installed backward.

[Shaun1305]

So the timing was waaaayyyy off. That being said, do I need the plastic timing cover to set the timing? The one on my car was pretty mangled. Otherwise I don't see any timing marks to go by...been driving it and doing it by ear and seeing what makes it run the best

[18Fiatsandcounting]

Yep, timing being waaaay off would do it. No, you do not necessarily need the timing cover to set the timing, and here's how you can get the timing pretty close by using the marks on the camshaft pulleys.

Put the timing light pickup on the #4 spark plug wire. Run the engine, and shine the timing light on the backside (facing the engine) of the two camshaft pulleys. There is a hole in each camshaft pulley, and it should be in close proximity to the nub/ridge on the camshaft housing. Both intake and exhaust housings have these nubs. Some engines also have a timing pointer for the cams that you can use. Zero degrees TDC would be when the holes/marks are aligned, and you can advance the timing by turning the distributor so the light flashes just prior to side by side alignment of the marks. Same as you would with the crankshaft/timing cover, but the camshafts turn at half the speed of the crankshaft so the "marks" are compressed by half. Hope all this makes sense...

Anyway, you can time against these camshaft marks and, while not as accurate as the marks on the crankshaft/timing cover, it can get you pretty close. Just be sure to use the #4 sparkplug for the timing light pickup, not the #1.

-Bryan

[SteinOnkel]

Also, newer, fancier timing lights have a value you can set them to but they will flash at TDC (if that makes sense).

So, time it statically like Bryan described and make a new mark you can get to with your light. A piston stop is your friend. Furthermore, the stock timing marks on engines are usually a bit iffy, don't expect it to be 100% perfect. Anyway, run the engine. Set the timing light to whatever max advance is for your year (probably somewhere around 36 degrees total advance, somebody here will tell you exactly what). At idle, it will flash way before TDC. Get a helper to rev the engine to 3500rpm and hold it there, then rotate the dizzy until the light matches up with your TDC mark. Done deal.

Cheers
Steiny

[Shaun1305]

You guys are the best! I'll report with my findings!

[wetminkey]

I do not change my timing light - I simply marked new markings on the metal engine cover. They align with the indents in my crank-pulley edges (passenger side). This is TDC.:

I measured to find and mark 10 and 20 degrees BTDC,...(distance along the pulley's circumference). Works great, and it's easy to use the marks on the passenger's side,...

[SteinOnkel]

Why did you use 10 and 20 degrees?