Gasket and belt recommendations?

[18Fiatsandcounting]

I know there is confusion on lining up all the marks, but below is how I look at it. I can't say that this applies to all Fiats, but it certainly has applied to all the DOHC 124 spiders in the model years I've had.

When the crankshaft pulley mark is lined up with its indicator (whether on the plastic timing belt housing or elsewhere), cylinders #1 and #4 are at TDC, and cylinders #2 and #3 are at BDC. With the crankshaft pulley lined up like this, both camshaft pulley holes should be lined up with their marks (either the tabs on the camshaft housing or the metal pointer mounted on top of the thermostat housing). In addition, the hole in the pulley for the auxiliary shaft should be pointing roughly in the direction of the idler wheel center stud. This last one isn't too critical and it's OK to be off by a few teeth.

OK, in this configuration, the engine is ready to fire on cylinder #4. NOT cylinder #1 as is often assumed, and hence the confusion. So, for engines with distributors, the distributor rotor should be aligned to aim right at the distributor cap post that goes to the 4th sparkplug wire. In some engines, the distributor rotor should be slightly past the #4 cylinder as that spark plug should have already fired at TDC, that is Before TDC. Usually, to get the engine started, you don't need to be this accurate on initial setup though.

That's pretty much it. Basically, when all pulleys that are driven by the timing belt are lined up, cylinder #4 is the one that is firing.

Also keep in mind that the camshafts and auxiliary shaft rotate at half the speed of the crankshaft, so if everything is lined up, you would have to rotate the crankshaft two full turns before everything is lined up again.

-Bryan

[wetminkey]

OMG!!
NO WONDER there's confusion! I have NEVER run across ANY type of engine that fires on a different cylinder than #1 when timing marks are set at their indicators. Not V8s, not opposed fours, not two cylinders (straight, OR horizontal), not even rotary. That is SO BIZARRE,...
Anyway, now I understand initial engine timing setup perfectly, THANKS! I'm REALLY glad that I asked!
Another 'mystery of the universe', explained. I'll make a note in the shop manual for a future owner, or mechanic,...

[bobplyler]

Because the crankshaft revolves at twice the speed of the camshafts/distributor,. you can set timing on either cylinder 1 or 4.

[18Fiatsandcounting]

Because the crankshaft revolves at twice the speed of the camshafts/distributor,. you can set timing on either cylinder 1 or 4.

Correct, and in fact, I often just put my timing light across the wire from the coil to the distributor. The timing light flashes 4 times as much as needed, but this method is also a good check of how consistent your sparking is. When the engine is revved, the timing light should be almost continuous, and "hiccups" in the light could indicate a spark plug that isn't firing consistently. The challenge of course is to find out which one.

-Bryan

[wetminkey]

Well,...the nice thoughts about "not having to remove the crankshaft pulley" are wrong - if you have the original timing belt shields,...!
So, I need to block the crank to remove the crankshaft pulley bolt. What are your suggestions, guys? It's an automatic,...
I hate to shove a screwdriver into the flexplate again,...

[18Fiatsandcounting]

EDIT: Ignore my post at the bottom, as somehow this forum mixed up my responses with something else (AKA user error).

I have never, repeat never, had to remove the crankshaft pulley to replace a timing belt, and I've had all of the variations of the DOHC engines. The belts have always been able to slip onto the crankshaft pulley if you turn the belt sideways and gently guide it into the space behind the crankshaft pulley and whatever else is behind it. Sometimes it has helped to slowly turn the crankshaft pulley as you're pushing on the "sideways" belt, thus allowing the belt to slip through.

So, I'm not understanding something by your latest post about removing the crankshaft pulley. The only time I've needed to do that is to replace the front crankshaft oil seal.

-Bryan



[Erroneous Post]: When the crankshaft timing marks on a Fiat 124 engine are lined up with the TDC pointer on the plastic timing belt cover, cylinders #1 and #4 are at TDC. Cylinders #2 and #3 are at the opposite cycle of rotation (Bottom Dead Center, or BDC). However, and this seems to be particular to Fiats, when the crankshaft is at TDC for cylinders #1 and #4, and the small holes in the two camshafts are lined up with the pointer, the engine is now set to ignite cylinder #4, NOT cylinder #1. That is, the distributor rotor should be pointed towards the #4 spark plug connector on the distributor cap. Don't ask me why Fiat did it this way; they just did.

-Bryan

[wetminkey]

I'll post a pic of the lower timing belt shield installed on the car manyana,...
My Fiat Shop Manual states removal, due to the shielding,...impossible to remove the belt from behind the lower shield, otherwise,...see official Fiat Shop Manual.
That's the way I had to do it before.