Loadomatic Question

[Eaglo]

I understand how the Loadomatic works along with its related Spark Control Valve.

Here's my problem. I believe specifications for a '65 200 state that there is no vacuum from the carb to the distributor at idle which would yield no vacuum advance.

Yet, even if I set the idle at 350 RPM, I'm getting some vacuum which gives me perhaps 2 degrees of added advance at idle.

I presume this may be from having an improper carb on the engine. The carb may be from a 170 with a slightly smaller venturi which generates greater vacuum. Or it may be normal for the carbs that were supplied with trucks which appear to have a vacuum port below the throttle plate this is exposed to the venturi vacuum at idle. .

Can't really see any problem this would cause. Can you?

The second issue is with the distributor. The breaker plate advances with vacuum but doesn't return fully. There's perhaps a couple of degrees added advance when I return to idle. Is this normal?

Before I go assuming that the distributor is gummed up I wonder if the advance is holding air that's supposed to bleed off?

Any of your thoughts would be appreciated.

Eddie in NY
'65 200 in a '67 Econoline pickup

[MPGmustang]

even if I set the idle at 350 RPM, I'm getting some vacuum which gives me perhaps 2 degrees of added advance at idle.

Well that's your problem... Idle should be no lower than 500rpm for manual and 650rpm for auto... personally I don't like low idle and found that 700-800 rpm on stock keeps it from ever bogging and is better for stop and go traffic.

Because you have such a low Idle, the engine is sucking more, making the SCV open and advance the timing so it don't die. your LOM timing without vacum should sit around 8*-14* making 20psi vacum from the Manifold... not the SCV on carb (but you knew that). read this forum here i posted some tips for the LOM closer to the bottom.

Good Luck!!

Richard

[Eaglo]

Thank you Richard. Yes, the 12 initial timing called for in the charts is too high at wide open throttle. 9 degrees works just fine and doesn't ping under load.

I'll idle up a little and see if that SCV vacuum cuts out.

I also looked through a Ford distributor book and it shows several combinations of the Loadomatic and Ford 1100 carb which give some ( 1 to 2-1/2 degrees) vacuum advance at idle.

So this old thing's running well now, Loadomatic and all! I appreciate the help.


Ed in NY
'65 200 in a '67 Econoline Pickup

[Lazy JW]

.....
I'll idle up a little and see if that SCV vacuum cuts out......

I'm curious about this too; my guess is that it won't. Let us know.
Joe

[Eaglo]

No, the vacuum increased sort of in a straight line with engine speed.

But I see no problem with 2 degrees of vacuum advance at idle... does anyone? Perhaps it's supposed to be this way.

[Lazy JW]

I see no problem whatsoever. It will be two degrees less for cranking, which is generally desirable.
Joe

[Eaglo]

Thanks for all the help.

It's funny that when you buy an old car, there usually isn't one single area that hasn't been messed with and messed up.