"Bob, Mark is correct.
If th
"Bob, Mark is correct.
If the decal is correct for the balancer OD, then all you must do is align the TDC (Zero) of the decal with the TDC (Zero) mark on the balancer.
The Port engine decal will install in the conventional direction ..... from TDC towards Port (clockwise)!
Unless there is a specific Stbd Engine Decal, I'm thinking that a conventional decal is also used on Stbd engine but will be upside down with the numbers increasing from TDC towards Stbd side. (counter-clockwise)
The corresponding timing marks will be the ZERO "V" notch of the timing chain cover "Timing Tab".
Bob,
You have a nice large opening to the flywheel.
To my knowledge, there is no decal available that would work here....., so the markings will need to be done by hand.
When setting timing, the procedure for BASE or TAT is same as though from the front engine balancer markings!
So in answer to your question...... Yes, once the balancer is marked accurately, you should be able to transfer markings to the flywheel.
Personally, I'd use a degree wheel and pointer and then make my markings........ but your idea will work.
Distributor Weights/Springs/Curve:
Bob, You can change springs/weights yourself using a kit that has come from "who-knows-where"!
You can then operate the engine, and with your new decal and timing light, you will be able to see where your curve and limit are as you raise RPM.
To adjust, you will stop engine, pull the advancing system apart, make adjustments by changing either a spring or cam weight or both......, then re-start engine, check curve/limit, repeat, etc. etc. etc!
It will be a PITA for you to do! I hate to see you risk your fresh, expensive engines if an error were to be made, IMO.
As a suggestion: You take both ignition distributors to a person who owns and has the skills to operate an old school Sun or ??? distributor machine!
This person will actually run them on this machine, and will check and set the curves and limits of both.
He will make the changes, and will run them again until he is satisfied that both curve and limit are met consistantly!
He can even re-bush the housings, and re-calibrated specifically for your particular engines. He will even give you a spec sheet for each one when finished!
You then simply re-install...... set BASE...... Check TA....... and you are DONE!
This curve and limit may vary depending on the engine build..... but there is a standard or "generic" curve that will work. It will be on the conservative side!
Example:
The use of dished pistons/small chamber heads will require that the TA (total advance) be held back some! (Max TA being let's say... 26* @ 3,400 rpm..... example only)
The use of a Q/E (quench effect) piston/head combination, will allow for a slightly greater TA and performance. (Max TA being let's say... 28*-30** @ 3,400 rpm.... example only)
You will need to select a curve/limit that best suits your particular engine build.
If you have a person do these on a machine, he may be able to recommend a correct curve/limit if he is knowledgeable on the SBC marine cruiser engines!
Unless your rebuilder is also experienced in owning, operating and tuning the SBC marine cruiser engines, he may not be the best to recommend this curve/limit. Again, IMO.
For this, I say, see your OEM manual, or an expert who knows and tunes these!
Bob, if I may elaborate on something here as an unsolicited FYI!
Just to clarify, (and unless I have misunderstood Mark) there is no BASE ignition Curve.
BASE Advance involves NO distributor mechanical advancing.
It is a static setting only for a low RPM spark lead! It remains BASE regardless of any mechanical advancing done via the distributor's advancing mechanism.
IOW's, if there was no mechanical advancing...... BASE advance would remain the same regardless of engine RPM. You'd be running at 10* BTDC @ 1,000 RPM, @ 2,000 RPM and @ 3,000 RPM..... all at 10* BTDC.
BTW, BASE should remain until approx 1,000 RPM! Only then should we start to see mechanical advance begin. (one more good reason for having these done on a machine)
The distributor's mechanical advance adds to this BASE advance as RPM increase so that we can pull some horse power from the engine (yet not allow for detonation). (I'm sure that you know this...... just throwing it into the mix here)
So if you were to have a BASE of 10* BTDC, the mechanical advancing is added to this 10* BTDC.
Example:
BASE setting of 10* BTDC + Mechanical advance of 18* = a TA of 28* BTDC @ X,XXX RPM.
As you know, the advance is progressive to a point of being Full IN......... hence the "curve" and "limit".
Remember that when reading a plotted curve graph, it will likely not include BASE, and will show only the distributor's mechanical advance.
Add BASE, and you have your TA.
And at the risk of redundancy... after all this work to lay out degrees for timing...., I'd again suggest the simple ole strobe type timing light to see this in real degrees and in real time!
Bob, Mark, Jeff.... Sorry for the long post...... I just place such a high importance on this and I find that even some very good mechanics will not fully understand it.
Hope it makes sense.
."
