TDC Question Options

[Darin300]

Hello,

Well I've finally started car last weekend (was excited since I haven't driven it yet)
but was running little rough, I checked points ect and found them in poor condition not to mention the piece of paper under them, trying to hold them straight. So you guys know how it goes, why just replace cap, rotor, ect, ect. I'll just upgrade dist now (Mallory), I'm going to do it anyways right?(Snowball effect). And here's where problem starts, finding TDC, After pulling valve cover and looking in manual It seems I found TDC to be little white mark on fan, the dist wasn't installed correctly so rotor doesn't line up with line on housing, but reading Pelican parts article it says line on flywheel should line up when motor is at TDC. I know for a fact that motor is at TDC and I have white mark aligned on fan but flywheel doesn't match. Is it possible flywheel was installed incorrectly and marks are off? Has anyone experienced this before?

[cgnj]

Hi,

The mark on the flywheel wll be at the top inspection port. You will need a mirror and a light to see it. I'm skinny, I just feel around, then mark the bottom of the flywheel. For peace of mind, I would go to tdc #3 and confirm that the mark appears at the bottom inspection port.

Carlos

[Darin300]

Yes I do get mark to appear, but it's not when #1 cylinder is at TDC. So figured flywheel was installed incorrectly, haven't done clutch yet on 914, so I don't know if there's dowel pin or something that ensures correct flywheel orientation. When line appears on trans inspection hole, #1 intake valve just closed and piston is bottom of it's stroke. So I take it that 's #3 TDC. When #1 is at TDC no mark just white mark on fan in timing inspection hole. I thought the two should match up, well according to what I've been reading..

[SLITS]

When changing flywheels, I have seen the TDC mark on the flywheel to be off by 15+ degrees in relation to the mark on the fan. I can't tell you why, but 2 engines I played with were that way.

Which is the reason I never use the flywheel for any timing or valve setting.

[Darin300]

Makes sense, that seems to be exactly what I'm dealing with. Thanks for the reply

[mrbubblehead]

When changing flywheels, I have seen the TDC mark on the flywheel to be off by 15+ degrees in relation to the mark on the fan. I can't tell you why, but 2 engines I played with were that way.

Which is the reason I never use the flywheel for any timing or valve setting.

Funny, i have found just the opposite. I never trust the fan and always go with the flywheel. Half the time you cant see the paint on the fans any more, and who knows if the fan was ever swapped with a 411, bus, etc.

What you need to do is pull the spark plug for cylinder #1 and find TDC for YOUR engine and make your own mark. You can damn near look down the spark plug hole with a little flashlight and rotate it to TDC. Both intake and exhaust valves should be closed. Thats what i do.

[jsayre914]

Which is the reason I never use the flywheel for any timing or valve setting.

(IMG:style_emoticons/default/confused24.gif)
How do you set timing without using flywheel???

[Cap'n Krusty]

There's a lot of questionable information being flung about here. If you can see the TDC mark on the FOUR CYLINDER flywheel (through the port on the top of the bell housing), it indicates you are on either TDC #1 or TDC #3. If you see it on the bottom of the bell housing, you're on #2 or #4. I have yet to see a T4 flywheel that wasn't marked correctly. That's NOT true of the sixers. The 2.2 and 2.4 cranks, and probably the 2.7 as well, a have the bolt pattern oriented slightly differently, and you have to put new marks on a 2.0 flywheel to get a correct orientation.

To find which cylinder you're on, you need to either look at the distributor or the valves. If both valves on one cylinder are loose, that's the one that's at TDC compression stroke.

The TDC mark is a line cut in the aluminum outer surface of the fan. It's a substantial and very precise line, not just a scratch or a paint mark. It's likely to be red, unpainted, or maybe black. I don't recall whether the bus fans have that mark in the same place or not. Unless you've lost the locating woodruff key on the hub, there's NO WAY the mark won't be in the right place if you have a Porsche fan, because the fan has a locating pin and 3 bolts. BTW, the distributor drive should be in the proper orientation to allow the distributor to be correctly installed.

Have fun!

The Cap'n