223 vac advance problem?

[Daves55Courier]

I had planned to replace the Load-O-Matic distributor with a Ford 240 cu in distributor with mechanical advance, but Cardone does not have any rebuilt cores so I will need to wait until they are offered. Unfortunately that means I am stuck with the original Load-O-Matic.
Fortunately, my fuel bypass system worked and now the engine runs without carb flooding out, however, when I try to rev the engine RPMs, it seems to loose vacuum to the vac diaphragm at the distributor. Engine looses power. If you put it in gear and try to rev engine, it will die, but it will re-start and idle with no problem.
I checked manifold vacuum. It is steady at 18.5 at idle speed.
I replaced vac can with a new one. Still looses vacuum.
Checked engine timing. Its right on the money at 6 degrees BTDC with dizzy vac disconnected and plugged. Checked timing again with vac tubing re-installed at dizzy can. It changes the timing about 1 or 2 degrees, which I think is about right.
Intake manifold does not appear to be cracked anywhere (and if it was it wouldn't hold vacuum at 18 on engine idle).
I put on a different Holley 1904. No change. It act exactly the same as with the other carb.
It is beginning to sound like the distributor advance cams are way too far out, but I never changed them and the engine never acted this way before. Any suggestions???

 

[bubba22349]

You could also use a 300 Ford Distributor in place of the 240, I do agree that the later distributor will be a big help in gaining better performance and economy. Have you read the excellent article on how the LOD system works? Here is the link http://classicinlines.com/Loadomatic.asp. It might help you in diagnosing the trouble.

When you rev the engine the vacuum is going to drop at the distributor vacuum diaphragm as well as the manifold, this is normal operation when the throttle bade is opening wider. And also the LOD doesn't have a centrivical advance system to carry the timing advance though the times of low vacuum. You could try advancing the base timing some more to 10 to 12 degrees BTDC this should help, some people even go much more up to 18. As long as the starter isn't kicking back or you get no more then a slight pinging under load you should be good to go. Good luck

 

[Daves55Courier]

Thanks Bubba, yes I am familiar with the Clasicinlines Load-o-matic operation and a lot of other info leaning towards ditching the Load-O-Matic for mech advance. That research led me to the idea of using the 240CID distributor. It will definitely be the easiest modification to achieve mech advance (as opposed to the 300 six cyl dizzy).
However, I am currently stuck with the Load-O-Matic and it DOES work, but not properly. I discovered the following:
I checked operation of distrib vacuum nylon ball check valve in Holley 1904 Carb. It does work properly and all vac passages are clear.
I checked tubing from carb to distrib vac can and it does not leak. Dizzy breaker plate holds position when applying vacuum with a MityVac.
Both primary and secondary advance curve springs in the distributor were set for the highest possible tension. I believe this is where the problem may be.
I backed off on the adjustments somewhat and was able to achieve very high RPM's without engine stuttering, then I re-adjusted engine timing back down to 6 degrees BTDC, then checked acceleration again. The engine runs good idling and at high RPMs, smooth and steady, however that does not mean I will get same results when engine is "loaded" under driving conditions.
Next step, I must finally break down and buy a dwell/tachometer so I can use the tach to determine how many degrees advance I get with several different RPM settings.
There may be another problem. I noticed that my distributor breaker plate has a shorter primary advance curve slot than the secondary (which means that the breaker plate will always top out when maximum vacuum pulls the breaker plate to the end of the primary slot). It made me wonder if this distributor was originally used in a Ford Tractor because they don't need high RPM's.
I looked at another 223v dizzy and noticed that both slots are long enough to permit maximum vacuum to pull the breaker plate to the end such that both poles hit the end of their slots. Alas that distributor is in real bad shape and I want to get a 240 CID dizzy anyway.
I am moving forward with my plan to try to get this thing to perform properly the way it is by making adjustments where possible.
Here is the factory data I will use to try my tests. Currently I have 6 degrees BTDC well marked on the crankshaft damper with a yellow line. For the purpose of these tests I will assume that twice the amount of space from TDC should be about 12 degrees, thus:
500RPM should equal approx. 4 degrees advance
1000RPM = 7-8 degrees advance
1500RPM approx. 10 degrees advance
2000RPM approx. 12 degrees advance.
Therefore I hypothesize that since initial ignition timing is set to 6 degrees BTDC with engine idling and vacuum plugged, the reading should be about 10 degrees BTDC at 500RPM with vacuum connected at the dizzy vac can. Is that right???

 

[Daves55Courier]

Finally got hold of a dwell/tach and hooked it up. Used the RPM meter to check timing at various engine speeds. Re-adjusted distributor advance curves by trial and error.
It seems to run pretty good now at all speeds with no hesitations.
On a somewhat unrelated note, I also looked at the dwell setting and it is locked at 38 degrees regardless of engine speed. My Load-O-Matic distributor is outfitted with a Pertronix Ignitor. The dwell should be 36 degrees ideally for the 223 engine. No matter how I turned the distributor to change the timing, the dwell angle did not change.
Since there are no points to adjust, does the dwell angle non-consequential?

 

[bubba22349]

The dwel angle would relate to the amount that a set of points are opening in relation to the distributor cam. I.e. You would open or close the gap to change the Dwel, on electronic type units dwel doesn't change with RPM like points do so it's more accurate on the timing. I haven't looked at a Pertonix in many years since I have been using the DSII units for decades. Are there slotted mounting base holes on the Pertronix so that its adjustable? If it's not I think 38 is good enough unless you want to try to mod the mounting holes a little so it can be changed in relation to the trigger wheel and then be set to 36. You might go to the Pertronix site and look at install specs and trouble shooting to see if there is any way to adjust it. Good luck

 

[Daves55Courier]

I have given this a little more thought. The purpose for setting points to the proper dwell angle is to allow the point contacts to close within a specified range after the point rubbing block passes the high point of the cam. If the dwell angle is WIDER than the specified limits, the points close for a longer period of time as the cam rotates, which also means that the points begin to close when the rubbing block is closer to the high point of the cam. This situation possibly might cause wearing out the point set sooner than they would with a narrower dwell angle. Points would also wear (or become pitted) if the dwell angle was set too narrow.
But with a pertronix unit, there are no points. It is just a magnet, so maybe having a wider dwell angle does not matter, but the design of the disc that fits down over the cam should be such that the magnet sensing slots are not too wide so as to cause pre-detonation.
So for now, I am not going to worry about it anymore. It runs good as is and achieves good acceleration. I have not driven it on the highway yet. That will be the ultimate test. If the performance on the highway is unsatisfactory, the only thing left I can think of to do is take the distributor out and have the advance curves dialed in by a Sun diagnostic machine. But I am trying to avoid that. I would rather fix everything myself. It's CHEAPER!

 

[bubba22349]

congrats on getting it dialed in