Timing under power and idle

[WrongWay]

So I adjusted for best RPM at cruising speed / power, it took a fair bit of CCW turn on distributor to do it. New adjustable main jet set. At idle I cannot get under 1K RPM. Unless I turn distributor CW a bit. Humm????

[Marian Claire]

Have you tried adjusting the throttle stop and/or the idle mixture adjustment?
Dan S/V Marian Claire

[JOHN COOKSON]

Don't forget to check the distributor advance under the breaker plate. It might be stuck in the advance position.

TRUE GRIT

[thatch]

WrongWay, Welcome to the forum. Ignition timing can really dictate the "personality" of an A4. I have long been an advocate of using the factory TDC rather than the "power timing" method. Recently I had the privilege of working with some other A4 owners who re-timed their engines using this method with some rather positive results. Rather than trying to describe their results, I'll let them speak for themselves. One of the tests on my Catalina 30 involved using the Moyer replacement distributor springs which greatly improved the power in the critical 1200 to 2000rpm range. My tests were conducted while using an engine vacuum gauge which is a good indicator of how an engine is "struggling" to attain more speed. Vacuum readings were definitely higher with the "lighter" Moyer springs installed. Stay tuned, we're just getting started on this subject.
Tom

[roadnsky]

Originally Posted by thatch

Stay tuned, we're just getting started on this subject.

Oh goody! More cool A4 stuff.
We can't wait!

[ndutton]

I was in the middle of looking to improve power when Tom mentioned his timing thoughts and concerns to me back channel. I had recently purchased a 10 x 8 two blade prop on ebay to replace my stock 12 x 7 two blade. After installing the new prop I was disappointed in the RPM improvement. It was better but didn't come close to my expectations. With the 12 x 7 I maxed out at 2100 RPM, the new 10 x 8 gave me a measly 200 RPM increase, now 2300. Simple math showed a 9.5% improvement from the prop change alone.

It was when I was whining to Tom about the amount I'd spent (prop + professional diver installation) for a disappointing result that he started talking about timing. Well, I was confident my timing was good, the engine ran well and has always started easily and (haruumpf haruumpf) I was experienced in the timing by feel method prescribed by Universal. Tom tactfully suggested maybe we should actually measure how accurate my timing was. Sounded like a good idea to me.

Tom gave me a homework assignment prior to him driving in for precision measurements. Because I have a Catalina 30 with the end of the crankshaft covered by interior structure (where Universal's only timing mark is located) I was to make my own readily visible timing mark as accurately as I possibly could using the accessory drive pointer I'd made for my spare engine under Tom's tutelage a while back.

I cut an access hole in the dinette seat riser to see the crankshaft roll pin, opened the distributor cap so the rotor would give a rough indication of when I was approaching #1 TDC as I turned the engine by hand. Once I was close I shined a flashlight on the roll pin and aligned it with the hand crank as vertical and on the flywheel cover notch as I could. Once there I marked the accessory drive pulley with white paint, then installed the Thatch timing pointer in careful alignment with the mark. That done, it was time to bring out the timing light.

I checked the timing at idle (no advance weight deployment) and whoa Nelly, my timing was alarmingly advanced, like an estimated 10°. Well, that was a sobering moment, maybe I'm not as adept at timing by feel as I thought. I loosened the distributor hold down clamp and rotated until I was on the mark, 0° BTDC. As the timing was adjusted the idle RPM dropped 100 RPM too. Time for a test run.

Whoa Nelly again, now I can reach 2600 RPM (a 13% improvement due to proper timing alone). Yeah guys, 2600 RPM for a direct drive A-4! Man, that's a reduction gear number. As always, YMMV. The significant improvement I experienced speaks in a large part to how off my timing was to start with but in my defense, I had previously followed [one of] Universal's published timing instructions carefully.

When Tom drove in with his precision TDC measuring equipment a week later we found that I'd been able to make a very accurate mark using the roll pin carefully. I've attached pictures of the new timing mark and Tom's dial indicator apparatus.

I'm looking forward to what so far looks like additional improvements with his advance spring testing. So far for me, prop change + timing precision has resulted in an overall 23.8% increase in max RPM.

[roadnsky]

That Spark Plug "Extender" is way cool!
Is that Tom's invention or your's?
Can you expound on the gauge a little?

Also, for clarification...
Is the pic of the roll pin not aligned to the mark showing us the position just BEFORE TDC or am I missing sump'n?

[thatch]

Sure Jerry, That tool has an arm on the bottom end that reaches over to the piston top. Using it is much like dialing in a camshaft in a performance engine. The process goes like this: First you rotate the crankshaft until the dial indicator stops movement on it's upward travel. You then rotate it in one direction until it drops a set amount, I use .050". I then make an indexing mark on either the flywheel or the accessory drive pulley. The next step is to rotate the engine in the opposite direction through zero and again back down to .050"and make another indexing mark. Halfway between those marks is an accurate TDC. Neil has proven that it is possible to establish a reasonably accurate TDC by using the crankshaft roll pin and a little care. Moyer's crankshaft rotation tool makes setting the #1 piston to TDC very easy.
Tom

[thatch]

Sorry Jerry, I forgot to add, Neil's picture of the roll pin is just to show off the hole that he cut in the Catalina 30 seat riser and has nothing to do with the crankshaft position.
Tom

[ndutton]

Yes Jerry, the roll pin picture was intended to show how difficult the Universal timing mark is to see when you don't have full access to the front of the engine. The pic was taken well after the timing exercise.

Edit:
I should have added the entire timing "homework assignment" Tom gave me took about an hour and cost pennies. The timing pointer was made out of 2 stainless hose clamps, the vent cover was on hand but originally came from eBay.

[sastanley]

I have just performed this exercise, and have been pleasantly surprised with the results. I didn't have a good mark on the accessory drive until yesterday (found some iridescent blue nail polish at CVS for $1.59!!), but just setting it to 0° at idle showed an improvement until I was able to get a better timing mark. I found that I was also several degrees advanced with the power timing method. I don't have Tom's fancy dial indicator, but I used a small allen wrench in the #1 spark plug hole to guesstimate TDC.

I don't have any real sea trials yet to report, and the prop and bottom are dirty, but I had more RPM at WOT than I did before setting it with a timing light, which was about 2,150 with the Indigo 3-blade and clean bottom. If I can get everything clean, I'll report back some more accurate RPM numbers.

My idle speed also went down about 100 RPM and she idles smoother too.

[thatch]

Shawn, Thank's for checking in on this subject. If you have not already done so, I would highly recommend cutting the flywheel access hole like Neil's. He was able to very accurately set TDC using the roll pin. Also, if you would like to take this one step further, I recommend changing to the Moyer replacement distributor springs. During recent tests I found that the engine had more pulling power in that critical 1200 to 2000 rpm range. I am currently using a cut-down stock C-30 prop which has put my rpms in a very similar range as my Indigo 3-blade. I'm betting that you will be in the area of 2500 rpms when your bottom and prop are cleaned.
Tom

[sastanley]

Tom, I believe I am using the correct Moyer springs, which I changed over the winter. I also have the access hole cut in the dinette seat. I used that to get close, and then used an allen wrench as a 'feeler gauge' on the piston. A visual inspection of the roll pin confirmed I was as close as I think I could get, as it was perfectly vertical. While tugging on the dock lines at ~1,900 RPM, I dialed up 17° of advance on the timing light and adjusted the timing to the mark. I also have a cheap little photo tach I will try to remember to use to compare to my tach in the panel.

Product No. - IGLM_10.1_292\


I have an event this weekend (it is the one "race" we do on the boat each season), which is a great excuse to get a short haul done to get some more accurate numbers on the way home Sunday.

[sastanley]

So, I took a buddy and went out for an "engine test" tonight. Unfortunately, I forgot the timing light , which I thought I'd left on the boat, so we were working off of timing settings fine tuned at 1,900 RPM last weekend tugging on dock lines (post #13). I expect that with full advance already achieved above ~1,900 RPM, the timing should not need further adjustment. I defer to folks like Neil and Tom for their thoughts on that.

Happy to report that we were able to get up to 2,250 RPM with a not-clean bottom or prop at WOT. Waiting on the marina to do a mid-season short haul this week (too many jellyfish to do it myself). Before today, I'd never seen more than 2,150 RPM, even fresh out of the travel lift.

The results seem promising. I'll try to remember the timing light when I go out again after the short haul.

All I gotta say is look out Daniel..us sailboats are coming for you..ok, maybe we have a few obstacles like a displacement hull.. link to Daniel's beautiful A4 powered "Tradition", at 3,500 RPM

edit - I was so pleased...below is an embedded 30 sec YouTube at 2,250 in a Catalina 30 with Direct Drive. I can't wait to hear it at 2,400+ if I can ever get it up there based on this new detailed data we are gathering.


[YOUTUBE]f41rXwdnAG8[/YOUTUBE]

[tenders]

So it's safe to assume the original question was planted as a way of catalyzing this discussion?

[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]

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.