timing advance, WOT and temp 454's

One thing has been bugging me since I got my boat last year. During the survey, my WOT results were 3980 and 3860. The previous owner of 7 years literally used the boat like a trawler and even commented to the surveyor and me that he had never gone as fast as we did during the sea trial.

Fast forward a year later and I've basically replaced all of the engine consumable parts, rebuilt carbs. Both engines start like they're fuel injected and run/sound great. BUT, the boat is slow. If I compare my RPM's and speed to other guys with the same boat, my WOT is basically their cruise speed.

I'm maxing out at around 3,700 and maybe 19-20 knots. Given the history and age (22 yrs), I started thinking about the timing advance. I'm about 5 knots off what other guys are running and about 8 off the factory specs. I don't want to run wide open but obviously this affects my 75-80% cruise ratio. Plugs look great, base timing is correct, props were just cleaned up (no change). Bottom could be better but it's not that bad. Running gear is all clean.

I have the original distributors with the Prestolite ignition. My understanding is the prestolite module just replaced the points but I probably still have the mechanical advance weights which could be the problem. The other reason is related to my recent temp post. When I get up over 3,000 RPM's, it seems like my temp does a quick 10 degree climb. I know if the timing is off, it will affect the temp.

I never used a timing advance light until today, here's what I got on one engine. The base timing is set at 10 degrees. I set the knob at 20 degrees for an overall of 28 degrees. At around 3,500 in neutral (my 10 y/o at the helm, hard to get right story), I was reading right around 8 degrees on the scale.

First, did I do this correctly and do those numbers indicate anything?

I haven't removed the cap and actually looked at the weights yet. I see a lot of posts regarding stuck weights and/or broken springs.

thanks

Bob

A big block Chevy advance should be 30 to 34 degrees BTDC. That is total advance so dont worry about the timing at idle yet. That would come into play with certain brands of distributors that use modules, since you have a Prestolite this doesnt pertain. Prestolite had different springs that would do the same as modules, i.e. 10* at idle plus the 22* degree springs would give you 32* total advance at wot. If I read between the lines you set the light at 20* and you had 8* showing on the damper that would be 28* total advance. Which may be your problem, remember too little advance will hurt perfomance, too much advance will hurt your engine. I would take the distributor apart and clean the weight posts and use a very light grease on them (there is a clip under the felt to remove). As far as springs they are very difficult to find anymore. You should see the total advance between 2850 - 3000 rpms. I would take the boat out and run it up to around 3200 rpms and set your lite for 30 or 32 degrees and adjust the distributor until it shows zero on the damper. See if you picked up any rpms. Leaving the distributor where it is back off to idle and see where to timing is. Hopefully between 8 - 12 degrees. Good Luck

I believe the total advance value is much more critical than the initial value, as long as the engines starts ok - both hot and cold.

Usually, you dial the knob (push the button(s)) on the light to move the timing mark back to Zero. Read the 'advance' off the "dial" on the light. Read the light's manual to be sure. It should also provide you a "calibration check".

Like Lee noted, OEM springs are damn near impossible to find. Most distributor shops can provide suitable alternatives. If not, the mallory spring kit should provide more than enough raw material to get a couple pairs to behave adequately.

Thanks guys, will do more work tonight. One correction, base timing is set at 10 degrees (I originally typed 8 which is why the math didn't work). I set the light for 20 thinking I would get a total 28, actually 30 (10+20).

Doing it that way, I was reading 8 degrees over 3k RPM's. If I understand what Lee is saying is I should ignore the base number (10), set it for 30 and see where it falls at 3k RPM's.

I'm going to look at one of the distributors tonight and see how the weights look.
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I just came across this post, guy also has a Prestolite setup:

"First thing, get yourself a timing light. Check the initial timing and the final. Your advance should be fully in by 3k rpm. You can check this in neutral. If you dont see close to 35 degrees (10 initial + ~24 advance) then something is wrong with your weights/springs"

So, he is suggesting to do it the same way that I tried? Is this the wrong way?

Sounds like you are on the right track. As you are adjusting the distributor with more advance you may see the rpms rise, thats good. When they level off and you gain no more rpms with more advance, take the distributor back to degrees where the rpms last changed. I found a vendor that has oem Prestolite springs....if you need the name and number let me know.

Any sense in setting timing at advance at "X" rpm and then seeing whatr it falls to at idle?

That is what I would Knuckle, set the advance for the best rpms and throttle back and see where you end up at idle. Hopefully between 8-12, adjust the carb and call it good. You dont have a lot of factory choices any more with the Prestolite as far as spring tensions. But, as MakoMark pointed out you can get spring kits for other distributors and get creative. Just have to be careful with the advance curve.

Lee, just so I'm clear. The Craftsman light I have has a rotary dial on the front. I should set that for 30, get it up to 3,000 RPM's and hopfully it reads around 0 on the damper.

Drop it back down to idle and hope for and 8-12 kind of reading. If you could get me the contact info for the springs that would be great. I didn't get a chance to take a look last night, hopefully by tomorrow.

Bob

Thats how you do it...if it doesnt read zero on the balancer turn the knob on the light until it does, then read where the knob is at. That will be you total advance, you now can move the distributor to change the advance. Here is the contact info for springs, have the distributor numbers ready. It will probably be a J1171 with another set of numbers.
George Hurst Co.
513 681 3120

Bob, I am a big advocate of strobing timing marks in real time/real degrees, and not relying on the electronics and algorithm of a digitally advancing timing light.... not to mention the possibility of user unfamiliarity and/or user error!

Short of aaaaaaaaaal the other issues that we can have with a marine gasser, Detonation is one of a gasoline Marine Engine's worst enemies.
(We're talking Detonation... not pre-igntion..... not same!)
Some engines fair this better than others...... but we can usually avoid it if our TA is set correctly. We can also and usually get our top performance if this is set correctly. It becomes a win-win either way.

With a Harmonic Balancer correctly marked off, and using a standard type timing light, we can see just where the advance is in what I call "real time.... real degrees"!
You can check this through the entire usable RPM range..... from BASE on up to where TA is Full In!

I'm a big believer in this procedure for any Ignition systems other than EST and ones using ECM/ECU's, knock sensors, and so on!
Yours will not be using any of these.

Now, on to your TA (total advance):

IMO here........ a TA # should never be offered to anyone without being accompanied with an RPM.
Basically, it is meaningless without an RPM.
I think that you'd be hard pressed to find an OEM spec that will offer a TA without also giving us the RPM at which this is to occur!
Without the two, you may as well set BASE, and be on your way. :rolleyes:

I've even seen well seasoned mechanics concern themselves with BASE only.

Aways see your OEM specs for YOUR engine when it comes to TA Ignition timing!

Sorry, but I become adamant about this topic because it is so often misunderstood, and so often paid such little attention to!

I also know that some of you guys love your digitally advancing timing lights, and I believe that there is a time and place for these!
Again, IMOO.

Yes, I'm stubborn on this!

Hey Rick,

I would love to meet you some day in person. Not being a good traveler, I guess that will remain to be seen BUT...You remind me of a very good friend of mine who has extreme knowledge of computers. In fact, his company is worth millions as a result of his skill. You will never win a debate about computer stuff with him as he really stands by his know how. I always enjoy reading your discussions and explanations on these topics

Please take this as the huge compliment it is intended to be

All:

I have done everything possible that I am aware of to cure the problem of my 1988 454 not going past 3200 RPM's. The other motor easily reaches 4000. Both motors have been rebuilt 600 hours on them. To date the following has been done in the past year.
1. fuel pumps
2. Carbs, new 1409's
3. Plugs/wires/dist.caps/rotors
4. Petronix modules and coils
5. Springs/advance weights checked
6. timing 10 degree base. Will not go past 18 advance. Other motor goes to 22 advance and turns 4000 rpm. Have tried different positions for the distributor with no results.
7. Compression checked revealed 115 to 120 all cylinders. I realize this is a bit low according to the books 130 to 140 but I doubt that this is the reason, but may be. Other motor is at 130 all cylinders.
8. fuel pressurure checked
9. exhaust back pressure checked
10. All tests are compared with good motor and except for the lack of advance are the same.

I have not changed the advance stops or replaced springs as both appear to be in good condition and check out according to the specs. I have the spring sets for the Mallory dist. I purchased from Summit, in case I need to change springs.

Boat is a 1988 Hatteras MY. Weighs in at 38,000. Cruise is 17 knots top is 21 according to specs. I have never seen anything over 19 WOT.

I can tell that the motor with the lower RPM's is struggling as the throttle is applied, up to 2500 the throttles remain the same but pushing past that, throttles become distant from each other as more throttle is needed for the lower RPM motor. That motor runs a bit hotter over 2500 RPM's about 5 degress but not even close to anything to worry about. By all indications this is an advance issue. Both start/run and idle the same and are very smooth. No oil usage at all.

Tanks are clean, anti syphon clean, filters 10 micron before pump, small cannister type after.

From what I understand reading these threads I should be seeing and advance of 20+the base 10 equaling 30 or close on both motors. I do not see this even on the one that turns to 4000.

What next?

Thanks,

Ron

fix the distributors. Is there an adjustment for max advance?

I'd suggest resolving the ambiguities first.

In DoneList #6, do the 18 and 22 degrees refer to total advance values? How were these determined?

I have not changed the advance stops or replaced springs as both appear to be in good condition and check out according to the specs. I have the spring sets for the Mallory dist. I purchased from Summit, in case I need to change springs.

Click to expand...

What specs were used for the verification?

My initial hunch is bad data or bad measurments.

With that much mass, you'll need both engines performing to spec to get on plane efficiently.

How long has this persisted; recent development or some timme after the rebuild?

1. There is an adjustment for maximum advance. I have the guage to make these adjustments in the spring kit from Summit. Spec adjustment is 24 and that is what the adjustment is and has been.
2. This refers to total advance values determined by the timing light and looking at the degree wheel on each motor. On the reverse rotation motor (18) the number is approx. becasue the numbering is below the start, if that makes sense.
3. The data was obtained from the Crusader manual that comes with the boat and the specs from Petronix that comes with the spring kit.
4. The boat always has and will still obtain planing speeds (15k) easily for its size.
5. I believe this to be a recent development as I have had this boat for 4 yeasr bought from the original owner. He had the motors rebuilt and was a machinist himself. The records and recipts on the rebuild are impeccable. The sea trial and for at least 2 years of my ownership both motors turned close to 4000 with no problem. I view this as acceptable given the age, size and rebuilds.
6. I initially bought this boat for a diesel conversion as that is what I had sold to move up. This boat ran so well and my usage dropped off so that after considering the costs I decided that until the engines died I would stay with them. With the accelerated costs of fuel I started just running this boat at desplacement speeds (10k) and would occassionally take it up on plane. I was not concerned about the difference in RPM's until I started to feel the starboard motor straining more than the port at the 3000 rpm level. That was about a year or so ago and is when I started the search for and replacement of parts that could cause this. Still glad I replaced all the things that I have so at least I know exactly what is there. Probably needed replacing anyway given the age.

As stated before, up to 2500 to 2800 rpms there is absolutely no difference between the two motors.

The other problem with removing and reinstalling the distributors is that access to the top of these motors is limited. The entire salon floor has been redone and I did not cut additional hatches. This will be corrected but not soon. When you have to work on the distributors you are bent over and crammed in to a small space over the motors. Your choices are to live with this or pull the distributor each time you want to make an internal adjustment. That is why I have hesitated to make advance adjustment to the stops and change springs. It is an adventure in body contortions.

I am preparing for a long trip to the east coast of Florida on Tuesday, about 250 miles. I am hesitant to start taking things apart again and will probably wait until I arrive and have the time to do so. I am thinking my next step is going to be adjusting the springs stops to the max and see if that helps. I do have the opition of taking the distributors to a shop and having them set up on a machine.

Long winded explanation but that is the story. Great website and lots of info here even for an ex diesel guy.

Thanks,

Ron

Ron,

If I have read your posts correctly you have 10 degree base and 18 degree advance on the motor that won't turn up past 3200 RPMS, for a total of advance of 28 degrees. The other motor has a total advance of 30-32 degrees and turns up to 4000 RPMs.

I suggest a simple test but you might want to wait until others on the board confirm that it is a good idea.

Start your engines, loosen the distributor on the affected motor, advance it 4 degrees, tighten it down and immediately take it out for a test run. If it turns up to 4000 RPMS, you have an advance problem; if it doesn't you need to look elsewhere. NOTE: Immediately afterwards put the timing back to where it was before. Don't run it this way for long as it could cause damage at low speeds.

Personally I doubt the power loss is from lack of advance as 28 degrees of total advance should be enough to get respectable perfomance.

Best wishes

I'm reading the 18 & 22 are total advance....still not sure how they are being read as all the 'degree wheels" I've seen need to be removed before running the engine. Timing tape maybe, on the circumference of the balancer?

You can buy a timing pointer with the proper orientation for the reverse rotation engine. That said, if you have a timing tape, you don't need it.

I'd say even 22 degrees isn't enough to allow the engine to run efficiently. You can physically scribe the balancer at the max advance value. only thing tricky is getting the mark on the BTDC side. that way you can use the current pointers.

I can appreciate the contorsionist moves so you may have to try different positions for this check...on the RPM deprived engine, can you hear the secondaries open? Have you tried the air valve to make sure it isn't corroded shut or the linkage binding? somewhere close to your max is about all you will see without the secondaries being opened, supllying both the extra air and fuel required for the higher rpms.

Major_tom's suggestion is a good one but I'd make sure you aren't fuel deprived before adding the additional spark advance.

I hope you'll are paying attention whem Mark tells you'll how important it is to get the correct TOTAL spark advance, regardless of that inital setting. If you can 'degree' your flywheel or damper pulley, then wing her good and see if the mark 'gets there', that's the way to go. If not, you need an advancing timing light to show you the same thing.

Jeff

I appreciate all the advice and opinions. I will be leaving on this 250 mile trip on Tuesday and have decided that I am going to leave well enough alone until I arrive. As we all know, this is "boating" where the smallest thing can wreck the best laid plans. It will be approximatley 2 weeks until I can get back into this problem and solution. I am going to hire some professional assisitance as this has now gotten beyond my expertice.

I hope everyone has a great holiday weekend.

I will check back in and let all know what happened.

Ron

Makomark:

You are correct on your understanding of the readings. This was done with a timing tape.

Carbs are 2 month old 1409's. Everything is operating correctly.

Ron