The Stovebolt Site Forums The Shop Area Engine Shop timing marks on a 235

I have read my shop manual, but am still confused. I am installing one of Tom Langdon's HEI distributors. According to the manual, there is a ball/ hole in the flywheel and some marks "UC" also. Which do I set at the pointer in the window when I install the distributor?
Also installed one of the water pump relocation plates per some of the recommendations here on the forum. Glad I did it--all the inner sheetmetal on the 5700 lines up now like it should instead of the rad being spaced forward at the top. nice installation. Bought a new pump from NAPA.
Instructions with the plate cautioned against using the later harmonic balancer/pulley. I have a spare '54 235 and the engine in the COE is a '58. Both balancers and lower pulleys are the same. Upper pump pulleys are alot different though--Later pump used a bigger pulley and it bolted on under the fan versus the pressed on cast pulley for the earlier model engine.

sbafarm,

Different flywheels have various markings on them that denote TDC and cam timing. Usually, when #1 is timed to the ball it gives several degrees of advance...sometimes as much as 6 deg.

My notes show markings of U-I-C on some flywheels. The mark 'I' is suppose to be TDC for #1. If you install your distributor so you have equal rotation in a advance direction as well as a retard direction, you don't need to get it dead nuts to a mark.

With the proper amount of movement in both directions (distributor) you can easily adjust the timing with a light to whatever you want...there is lots of leeway here.

Don't go nuts trying to get a flywheel mark right on the money!

Stuart

Thanks Stuart. So what is the mark for TDC? I would rather not pull the valve cover. Luckily, the HEI will turn however far I need it too, so timing won't be a prob, I just want to get in the ballpark first.

sbafarm,

Is there a steel ball embedded in the flywheel? This is the most commonly thought of TDC, although it is probably an actual BTDC timing mark. Use the 'U' or the steel ball to get in the ballpark.

With a timing light you will set the engine to run its best regardless of any mark on the flywheel. With unlimited rotational capabilities of your new HEI, you will be able to tune to your hearts content.

I can't tell you if any mark on the flywheel is actual, true TDC of #1 piston. It isn't that important as I see it.

Stuart

I think I have just a hole in the flywheel-- maybe it lost it's ball--LOL. That is the mark that shows when I run the engine up to TDC on #1. I'll stab the dist. there and should be good. I appreciate the info Stuart

Don't know if this helps but on our 1957 235 the marks look like this I O I with the " O " in this case as a stand in for the small BB that is impressed into the flywheel. For the 1957 235 engine timing is pointer lined up on the BB..... so states the manual. I think the other marks are for valve timing but I could be wrong and will be corrected in short order.....T/C Steve

There's a quick way to find true TDC, and it's pretty simple to do. Take an old spark plug and machine or grind the area where the porcelain meets the steel until the porcelain can be knocked out, leaving just the empty steel shell. Drill & tap this piece with a 3/8"X16 thread and install a piece of all-thread rod about 3 inches long. Add a lock nut if desired. Screw this device into the #1 spark plug hole, and adjust the all-thread until it sticks into the cylinder a short distance. Turn the engine by hand (spark plugs out is easiest) until the piston stops against the rod. Mark a spot on the flywheel or the crank pulley adjacent to a bolt head or some other reference point with a center punch, felt-tip marker, or grease pencil. Turn the engine backwards until it stops again. Mark that spot. TDC will be exactly halfway between the two marks.

I've done this procedure on every race engine I've built for the past 30+ years, and it's amazing how far off some factory TDC marks are!
Jerry

sbafarm;
I hope this isn't way more information than you needed, but it sounds to me like your looking for TDC on #1 so you can locate your dizzy (?) Problem is, just because #1 is TDC doesn't necessarily mean that's when your dizzy points to #1, it has to be TDC on the compression stroke!

There's a couple of easy ways to determine this:
1. Remove the valve cover. Rotate the engine clockwise (from the front) by turning the fan. Watch the #1 intake valve, when it opens, then closes, the next BB mark, or whatever you're using, is the right one, point the dizzy rotor at #1 tower.

2. Remove #1 spark plug. Rotate the engine as above. Stick your finger into the #1 plug hole (probably will need a helper for this). When you feel a rush of air blowing past your finger, stop when the BB appears in the window. Point the dizzy rotor at #1 tower.