Finding TDC
 

Hello All~
I am trying to set the timing on my car, and I had a couple of questions about finding TDC to mark my impeller.

1) (this one may sound stupid, but) If the timing on the car is way off, will the mark on the distributor be accurate?

2) Is there any quick and easy way to know that once I have the mark aligned, that I am at the true TDC and not 90 degree's off?

Thanks,
~Eric

??? if you bring the impeller to TDC, the rotor will probably not point to the mark on the dist housing (as i understand your question as you have stated). i think it should point to 27 degrees before the mark on the dist since that is how a 2.0L should be timed, 27 degrees BTDC @ 3500 rpm (or some such rpm, refer to a reference to make sure)

the slot in the dist drive gear should point 12 degrees off the line in the engine case. see any good reference for information. if that is correct, then rotor will be correct and the dist should be adjusted for correct timing. it's easy to put the dist drive gear wrong such that timing problems will result.

as you can read, this is kinda hard to explain but your question/problem has alot of parameters which must first be correct before giving the answer. start with verifying the basic settings, then go on. one bad link in the chain, yada yada......

there is also a mark on the flywheel that indicates TDC.

Here is a pic of a 74 2.0 impeller.

http://www.pelicanparts.com/techarticles/914_timing/20impeller.JPG

And here is the article it came from. The pic is at the bottom of the page.

http://www.pelicanparts.com/techarticles/914_timing/914_timing.htm


Note: one revolution of the impeller results in one half revolution of the rotor.

There are a lot of postings on how to find TDC. Click on the "search" button, enter "finding AND TDC" into the field, and select the 914 Forum to do the search in.

The notch in the distributor body isn't very accurate regardless of the timing. Note that the rotor covers something like 15 degrees worth of distributor rotation, so "when the rotor points to the notch" is a very approximate thing.

You can use that to determine if you're on TDC #1 or TDC #3, after you have found the notch on the fan. (Or flywheel.) The position of the rotor will point roughly toward the #1 plug tower (usually left-front) when you are at TDC #1. You can also tell by popping the valve cover off and checking the two valves for that cylinder. If both have some slack, that is the cylinder that is at TDC.

--DD

Its Simple remove Spark plug #1 Remove valve cover So you can see the rockers for #1 rotate motor till both valves are closed, Use a Small Wood Dowel insert in spark plug hole rotate motor until dowel is at highest spot and you are at TDC regardless of fan Markings
Hint Use white paint to mark the flywheel thur the hole in case At TDC

Steve