Better timing reference mark

[sdebaker]

The timing marks on the plastic, cam-belt cover on my 1800 are quite nebulous. They are about an inch or more away from the notch on the crank pulley. Pretty hard to line them up with what I consider adequate accuracy. Anyone got a suggestion for improving this situation?

[BEEK]

the only other mark for tdc on the early engine is if you remove the crank pulley, there is a reference mark on the seal plate and a machined in mark on the cog.

you can also remove #1 spark plug and use a screwdriver to check tdc as well. but i have never seen a problem with the factory orientation on the timing cover , use the long line and all is good.

[BEEK]

the only other mark for tdc on the early engine is if you remove the crank pulley, there is a reference mark on the seal plate and a machined in mark on the cog.

you can also remove #1 spark plug and use a screwdriver to check tdc as well. but i have never seen a problem with the factory orientation on the timing cover , use the long line and all is good.

[sdebaker]

the only other mark for tdc on the early engine is if you remove the crank pulley, there is a reference mark on the seal plate and a machined in mark on the cog.

you can also remove #1 spark plug and use a screwdriver to check tdc as well. but i have never seen a problem with the factory orientation on the timing cover , use the long line and all is good.

The problem is the opportunity for parallax error, which increases with the distance between the object and the reference point. I'm interested in better-than-shade-tree-mechanic accuracy in timing. Most other engines with which I work have the timing-reference mark or pointer much closer to the pulley mark. Hence, the relationship between the two is much clearer and opportunity for parallax error reduced.

I understand, and use, the method of finding TDC by measuring piston position (which I do with a dial indicator). But, if I determine that within one-trillionth of a second, how can I clearly relate that, accurately, to the timing marks on a running FIAT engine?

I time to total advance, not idle advance.

[SoFlaFiat]

"Shade tree mechanic"
What the heck does that mean?
Sounds insulting to me....
TDC IS TDC, by what ever means you find it! Don't trust the timing marks because they are too far from the pulley? Pull the plug and use anything you like to get #1 to the top and go from there. What's shade tree about that? OR, get new glasses!!!
Sorry!!! But sometimes it amazes me what people say!

[fiat218]

"Shade tree mechanic"
What the heck does that mean?
Sounds insulting to me....
TDC IS TDC, by what ever means you find it! Don't trust the timing marks because they are too far from the pulley? Pull the plug and use anything you like to get #1 to the top and go from there. What's shade tree about that? OR, get new glasses!!!
Sorry!!! But sometimes it amazes me what people say!

You are shade tree

[DocGraphics]

So here is what I did last year when I decided to run wihtout a timing belt cover after replacing all belts & seals in the front of my 1800 (1978 1756cc 132.A1.040.6).

I Aligned the crank to TDC using the mark behind the crank pulley (verified with a wood dowel down the spark plug hole to be sure was TDC) Reattached the pulley & marked the timing mark on it with yellow paint, as I was not putting the timing cover back on I Fabricated a marker which bolted on with a couple of the lower cover bolts (slotted for adjustment).

I printed out a timing degree wheel to the same size as the crank pulley & mounted it with tape & marked on the timing marker the associated 0*, 5* & 10* spots & cut those spots into timing marker as points that floated just above where the timing point is on the crank pulley.

This turned out real good, looks real nice & is real accurate but was alot of fab work to make it happen right.



I know that the stock timing marks (on the plastic cover) are a ways away from the mark on the pulley but as you are looking inline with them from the drivers side fender area (with a timing light) they should appear to be directly above the crank mark. Does that make sense?

Cover accuracy ehh.. close, find YOUR TDC & look from the angle the timing light would come in at & see actually how close the stock cover markings are. (my stock cover was so warped & cut into but the fan belt it was useless)

For total advance timing you could uses the degree wheel to place a second mark on the crank pulley (different color at specific timing) to line up with the 0* mark (was my plan to mark mine at 35* total advance but forgot...so far)

[rja]

some of those old a-series english cars...you had to crawl under them to reference the timing marks. plus, i was always more worried about the "lacks-a-pair" error than any of that other stuff he was talkin' 'bout!

[SoFlaFiat]

Damn rja!!! Another great signature!!! Happy new year!!!

[rja]

Damn rja!!! Another great signature!!! Happy new year!!!

here's another. i never finish anyth

[sdebaker]

"Shade tree mechanic"
What the heck does that mean?
Sounds insulting to me....
TDC IS TDC, by what ever means you find it! Don't trust the timing marks because they are too far from the pulley? Pull the plug and use anything you like to get #1 to the top and go from there. What's shade tree about that? OR, get new glasses!!!
Sorry!!! But sometimes it amazes me what people say!

Didn't mean to insult anyone. Just mean the alignment of the pulley notch with the marks on the distant timing cover is not very visually precise. Add that error opportunity to the rather casual way the plastic timing-belt cover is attached to the engine, and it is even less likely that I can hit the correct timing using the existing references.

Since I time the engine for max advance with it running, using an adjustable-advance timing light, the screwdriver or dowel in the spark-plug hole is not practical for determining TDC as a reference point.

[sdebaker]

So here is what I did last year when I decided to run wihtout a timing belt cover after replacing all belts & seals in the front of my 1800 (1978 1756cc 132.A1.040.6).

I Aligned the crank to TDC using the mark behind the crank pulley (verified with a wood dowel down the spark plug hole to be sure was TDC) Reattached the pulley & marked the timing mark on it with yellow paint, as I was not putting the timing cover back on I Fabricated a marker which bolted on with a couple of the lower cover bolts (slotted for adjustment).

I printed out a timing degree wheel to the same size as the crank pulley & mounted it with tape & marked on the timing marker the associated 0*, 5* & 10* spots & cut those spots into timing marker as points that floated just above where the timing point is on the crank pulley.

This turned out real good, looks real nice & is real accurate but was alot of fab work to make it happen right.



I know that the stock timing marks (on the plastic cover) are a ways away from the mark on the pulley but as you are looking inline with them from the drivers side fender area (with a timing light) they should appear to be directly above the crank mark. Does that make sense?

Cover accuracy ehh.. close, find YOUR TDC & look from the angle the timing light would come in at & see actually how close the stock cover markings are. (my stock cover was so warped & cut into but the fan belt it was useless)

For total advance timing you could uses the degree wheel to place a second mark on the crank pulley (different color at specific timing) to line up with the 0* mark (was my plan to mark mine at 35* total advance but forgot...so far)

Thank you. An elegant (in engineering terms) solution, and similar to the default I expected to use. But the picture of your finished piece will be a big time saver for me. I suspect it will be much-more-accurate than the marks on the plastic cover, even if the cover was in good condition and closer to the pulley.

Certainly in my 1977 it is not possible to sight directly along the raised ridges on the plastic cover to the pulley notch. The angle is such that one would need to look through the fender to do that. One must estimate where a line along one of the ridges would hit the pulley while looking at the the side of the ridge.

What was the source of the timing wheel you printed?

[DocGraphics]

I just did a google image search of a timing degree wheel, down loaded the one I liked, sized it in Corel to the same size as my crank pulley, printed out on paper & then glued it to a thin piece of plastic

[Zippy]

"Shade tree mechanic"
What the heck does that mean?
Sounds insulting to me....
TDC IS TDC, by what ever means you find it! Don't trust the timing marks because they are too far from the pulley? Pull the plug and use anything you like to get #1 to the top and go from there. What's shade tree about that? OR, get new glasses!!!
Sorry!!! But sometimes it amazes me what people say!

That's funny. I have always considered myself a shade tree mechanic. I never received any training on auto repair (as a matter of fact my father's solution to a dead battery was to hit it with a baseball bat) but I have always been able to fix almost anything that was wrong with my cars and trucks. Most of what I learned was 40 years ago. I learned how to pull the axle and repair the brakes on my 1 ton truck by watching a mechanic doing it to a dump truck at the dump. Now it's so much easier, just watch a youtube video.