Finding Timing Marks

[PeteD]

With lots of advice from you folks, I just completed switching my carbed 1.8 back to the stock 205AA distributor and away from the 009. I timed it "by ear" and went for a drive. What a difference all that extra advance and a the retarding under load makes!

I have been fiddling with the timing by turning the dizzy, driving, seeing how I like it, and repeating. This is not very scientific. I would like to just set it to 35deg at 3400RPM, but for the life of me, I cannot find a single timing mark on the my fan. (Perhaps the AC pulley moves the fan just enough that little/no timing mark is visible. {I am not using the AC, don't even have a belt on it, but that is another story}). If I just had one timing mark, I could easily measure over and mark other spots. SO, HERE IS THE QUESTION: does anyone know how far over in millimeters or inches the TDC mark, or any other mark for that matter, from the left of the wide part of the fan is on a 1.8 fan? To clarify... The fan has lots of thin blades and a few wider sections that connect the front and back of the fan. Since I can tell when I am near TDC by looking at the distributor, if I just knew where the TDc mark should be in relation to the left edge of the wide section nearest TDC, I could figure it all out from there. (My plan is to actually paint the fan blades different colors and make a table of the degrees for each blade, then interperlate as necessary when setting the timing.)

(I have an old fan off a 1.7L but understand the markings on it are different than on the 1.8. If someone can authoritatively confirm that the TDC points for the two fans are the same, I could work off of that 1.7 fan (which holds open the back door to my garage on warm days).

PS: yes, I read the Pelican Tech Article on timing which is excellent, but does not cover carbs.

Many thanks and happy holidays!

[Dave at Pelican Parts]

The TDC points for the two fans are the same. Authoritatively. The fans are keyed to the hubs, the hubs are keyed to the crank. There is only one way each goes on, and it's the same way for all Type IVs.

I think it was 8.5 fan blades from the nearest block, but I'm not at *all* sure on that. The D-jet timing mark (27 deg BTDC) is 4 fan blades from the nearest block. But that is NOT the TDC mark. The timing mark is a notch, while the TDC mark is generally a dot or a '0'.

--DD

[JP Noonan]

In the Type-IV world I've only found one consistant, absolute way to find TDC with the motor together. There is a "slash" cut (cast?) into the flywheel. It can be viewed either through the inspection hole at the bottom of the trans (at that point the motor is 180 degrees BTDC) and through the a hole in the top of the trans, for this one you need to push the piece of engine tin (the one that goes across the entire back of the engine compartment) out of the way to see it. At this point, when the slash lines up with the parting line of the motor and the rotor is pointing toward the #1 tower, the #1 cylinder is at Top Dead Center. Now the fun part.

I have a fan from a bus with NO I mean NO timing marks on it. I have on from a 1.7L (I think?) with 0 and 27 degree marks . A 2.0L with 5 and 27, no 0 mark, and a 1.8L with the 7.5, can't remember if it has a 0.

To mark the bus fan, I lined up the slash and rotor, then VERY CAREFULLY marked the fan where the "V" in the fan shroud was. I then removed the fan and used the measurment in mm from the Haynes book. The scale on the Pelican tech article is even easier to use. I think I also matched the fan up to one of the fans with marks as a check.

Timing a carbed 914? Check the 914 club forum I think someone there a ways back had some info. I would think that if all the vaccuum ports are dissconnected and pluged, bring the engine up to 3500 and set total timing there (you say the 205AA is total at 34? sounds right). Haynes lists the 1.7L carbed and 1.8L L-Jet as needing 7.5 at 800-900 RPM, I dunno.

[PeteD]

Thanks guys! I knew I could count on you!

I will work from that 1.7L fan that I have and then add to the markings on the Pelican timing template. (perhaps we'll add an addendum for that article). Warm weather the next few days, so I'm looking forward to seeing the effects of this re-tuning.

Thanks again!

[Dave at Pelican Parts]

DOH! I posted my reply above when I was away from home; no references or spare fans available to look at. The 27 BTDC mark is ONE fan blade to the right of a support, while the TDC mark is 4.5 fan blades to the right of that same support.

The Bus fans should have some sort of timing marks on the forward part of the fan, the part with the alternator drive pulley. I think...

I have heard that replacement fans had no marks at all, so whomever was doing the replacing had to transfer the marks from their old fan.

Anyway, I'm still certain about the fan only fitting on the crank one way. And all the Type IV fans are built and oriented the same, AFAIK. All of the 914 ones I've seen sor far definitely are.

--DD

[wjdunn3]

BTW, there is a tech article on this site that has a downloadable Adobe PDF file with a template in it for marking the timing marks on the Fan. I have used it. You need to have Adobe Acrobat Reader installed on your PC (it is free software from www.adobe.com, there is a "get acrobat reader" button at the bottom of the web page) to open the template file.

[JP Noonan]

DD is right, the fan hub is located on the T-4 crank by way of a (woodruf?) key, and the fan is located on the hub by way of a dowel.

BTW the GE block fan I had with no marks came from a bus motor that didn't have a sight hole. You know, the little black plug that un-screws? The fan shroud was solid at that point. I don't have a clue how it was timed, maube you're right and mine was a replacement or was missing something.

B.BTW when I said "Type-IV world" in a previous post, I meant "914 Type-4 world" I don't think the bus or sedan blocks have the slash in the flywheel.

[PeteD]

All this input has been very helpful. Here is my boildown. The 35 deg BTC point that I was seeking is about 3/4 of the way left of the edge of the fan spreader, which is 4.5 blades away from TDC.

The great enlightenment came to me when I got out an old 1.7 pulley and observed that the marks are on what ends up being the REAR end of the fan. I was looking for marks through the FRONT "V" notch and forgot that there was a REAR one. Once I got my body far enough into the engine compartment to see the rear "V" notch, it all came together... (My wife was pretty sick by that point of turning the left rear wheel while I stared in the hole...)

[michel richard]

JP,

Out of interest, how does one know that the flywheel is in the right position, relative to the crankshaft ?
I'm not certain but I can't recall anything that would keep the flywheel from being in any one of five positions relative to the crank. Is this something one has to keep in mind when putting an engine back together ?

[JP Noonan]

The T-4 has a roll pin (at least the 2.0L crank I have in my closet has a steel roll pin in it). Makes it a PITA to stand on its end, but I digress.

As I remember the 911 series motors have one of the 6 (or is it 8) flywheel bolts offset. So that the holes only line up in one position. Got a cracked 3.3L 930 crank sitting around as a bar stool if anyone wants it

(just in case you think I'm serious, it was cheaper for my buddy to buy a used $1000+ crank than to weld, grind, and re-heat treat the cracked crank.)