Timing under power and idle

[ndutton]

It may look like Wrong Way's original post was a setup but such was not the case. We were in the middle of doing the timing work and in my case had exciting results that I was itching to present to the forum when this thread popped up. Wrong Way's questions were his own, we seized the opportunity.

Our work is not done yet, still working on advance curve testing.

[thatch]

Tenders, I can assure you that what Neil said is the absolute truth. WrongWay's question just happened to come at an opportune time so I jumped in with with the results of some recent tests. Personally, I have been working on an easier, more accurate method of timing our A4's since buying my first one in 2009. If Universal "dropped the ball" while designing these engines, it would have to be in the area of establishing a good ignition timing method.
Tom

[JOHN COOKSON]

What If There Is Good Access To The Front Of The Engine?

I've timed engines before but it has been awhile. Sort of have "lost it".
Would this be the correct procedure to time an A4 when there is good access to the front of the engine?
Be sure the advance moves freely.
Paint the half of the roll bar(roll pin?) that lines up in the timing mark notch when engine's #1 cylinder is at TDC compression with white paint. It will be easy to tell when #1 cylinder is at TDC compression or somewhere near by looking at the position of the rotor.
Hook the timing light to #1 cylinder and start the engine. While the engine is at idle RPM turn the distributor so when the light flashes the marked roll bar lines in in the timing mark notch.

TRUE GRIT

[thatch]

John, That's about it. There are a couple of other things to watch out for though. If you have been power timing your engine, you may notice that your idle rpms will decrease. If this happens, simply adjust the idle speed adjustment screw on the throttle arm to a comfortable idle which should be in the area of about 800 rpm. It is important to note that the distributor should be at zero advance at this point. During Neil's test session, he proved that it is possible to come very close to perfect TDC by using the factory roll pin as a reference mark. A couple of side benefits of using this method is the reduction of blow-by and less premature engine wear.
Tom

[sastanley]

John, Tom is on point, and he is the pioneer of this updated technique we are trying out. One thing I will comment on is the width of the roll pin..it is "several" degrees wide, and I've found it can skew results either way with a timing light, but I will also affirm it seems accurate when setting TDC (using the middle of the wide pin!) I had my engine power timed for years (and anyone around here has seen me chronicle this process). Several years ago I used the roll pin with a timing light and thought I was good to go.

However, based on the information in this thread, if you can get an accurate mark at TDC and then a pointer on the accessory drive, I've personally found it makes a world of difference to back up the research and tests Neil and Tom have been doing. One caveat, the C-30 has poor access to the flywheel, but GREAT access to the accessory drive.

I took a friend out on Wednesday to watch the beer can races and do some engine runs (still dirty bottom and prop). He is a retired Navy mechanic, and he has watched me struggle and work thru this A4 process for 8 years. He said, "Dude, she sounds as good as I've ever heard her sound."

I just got word from the marina that they short hauled and cleaned the prop for me yesterday (an expense I begrudgingly accept in summer with jellyfish), but I hope to get more data to report back to Tom, Neil and the Moyer community when I go cruising this weekend.

I am hoping for a hundred more RPM with clean running gear and bottom.

[thatch]

Thank's Shawn, The bottom line of this whole exercise is to attain a smooth running engine that will push our boats at their designed hull speed. In the case of our Catalina 30s, that's about 6.7 knts. Adding a mark and pointer on the accessory drive pulley makes sense on a C-30 because of the right side access panel. On engines where you have to work from the top, using the roll pin and v-notch mark will probably still be easier.
Tom

[ndutton]

I'll further support Shawn's comment on the roll pin as a timing mark. It's too thick and there is too much distance between it and the flywheel cover for precision. Another shortcoming is the small radius the roll pin swings. Having Tom's pointer almost touching the accessory drive pulley allows for uber precision with a timing light. Tom has yet another timing mark enhancement he has developed for those with poor accessory drive visibility and good flywheel access. I'll let him describe the details.

[thatch]

I guess that Neil is talking about the modification I made to a flywheel cover. It was a relatively simple matter of extending a line from the roll pin out to the edge of the flywheel face and cutting a 3" viewing slot in the cover. I did this while checking the advance rates on several different distributor springs. The Moyer crankshaft rotation/timing tool would make establishing this new mark easier and very accurate.
Tom

[tenders]

I was just razzing you guys about planting the question. This is fascinating work and I'm enjoying the details but can't help but notice that the OP doesnt seem to have joined or chimed in. (Question was sort of vague.)

[ndutton]

A reminder that the MMI timing tool (NOT the starting hand crank) is made so the handle is aligned with the crankshaft roll pin providing greater accuracy when setting the engine at TDC. For the C30 guys (and others) who have to reach through structure to access the crank, bending the handle slightly near the hub provides necessary clearance from the structure.

[romantic comedy]

Is there an agreement as to the timing settings?

[ndutton]

The specs I have (Robert Hess) are 0 degrees BTDC at idle and 17 degrees BTDC at 1800 RPM.

[sastanley]

So, I did a short haul and went cruising. I am not quite getting 2,500 RPM like Neil ( we are running different props), but I am getting 2,250 to 2,300 RPM with the 10 x 7.4 (I think first generation) "winglet" Indigo prop. Ran for several hours today at 2,000 RPM at 5.6 knots at 170°F. 10° degrees cooler than before, and she seemed really happy today and was never struggling.

Still need to confirm RPM with my phototach, and maybe I'll pull out the timing light sometime soon...I was just too busy cruising to do that this weekend, and totally pleased with the performance.

edit - RC, as Neil noted, I have set my boat at 0°BTDC (at 1,000 RPM) and then ran her up on the dock lines which I could muster 1,900 RPM and the timing light measured it at 17° BTDC.

[ndutton]

Shawn, our props are the same diameter and pitch. The differences are 2 blade (mine) vs. 3 blade (yours) and you have the winglets. Maybe that accounts for the differences.

[sastanley]

Neil, since we are getting technical in this thread, I wanted to make sure we are making notations of all the differences and anomalies. In this case my 3 blade Indigo vs. other props in this experiment like your 2-blade. I don't know how to compare the performance differences yet, but I figured they were worth mentioning.