Vehicle Emission Control Decal

[Gary Lewis]

Gary, the way I understood it on Darth, the restriction meant the vacuum advance came back in a little slower after accelerating (probably to help keep the NOX levels down) but with the engine hot it needed to come back in faster.

You may be right, Bill.

Jeff - When you test please see if you can tell a difference in the total advance with the restricted vs unrestricted vacuum. That should answer our question.

[81-F150-Explorer]

You may be right, Bill.

Jeff - When you test please see if you can tell a difference in the total advance with the restricted vs unrestricted vacuum. That should answer our question.

I've been wondering if he's got the right temperature PVS for his application?

Green is 125 to 131 degrees Fahrenheit.

If the purpose of the PVS is to help cool an overheated engine, in this application, then the Green PVS is too cool isn't it? When normal engine temp is 190F+

Wouldn't he need the 3 port Black (Original color RED) PVS marked "G1" that operates between 222F and 228F?

Ported Vacuum Switch - Napa

Or am I missing something?

[Gary Lewis]

I've been wondering if he's got the right temperature PVS for his application?

Green is 125 to 131 degrees Fahrenheit.

If the purpose of the PVS is to help cool an overheated engine, in this application, then the Green PVS is too cool isn't it? When normal engine temp is 190F+

Wouldn't he need the 3 port Black (Original color RED) PVS marked "G1" that operates between 222F and 228F?

Ported Vacuum Switch - Napa

Or am I missing something?

I think you are right about the switch not working to cool the engine. So if that is the intent for that switch then he does have the wrong one. But, how did we settle on the one he has, which is green? I think maybe I've lost something?

The closest parts list I came up with is below, and your list is on the right. How to we get from one to the other? Both of the valve assemblies shown are said to be "black/green", but no such animal exists in your chart.

[BigBrother-84]

Clean both the timing pointer and the marks on the harmonic balancer, and put a but of chalk or white paint on the 10 degrees Before Top Dead Center on the balancer.

Why, oh why everything always seems so simple when done by others?

Went under the truck with a marker and… just don’t find any marks down there.

 

[BigBrother-84]

Clean both the timing pointer and the marks on the harmonic balancer, and put a but of chalk or white paint on the 10 degrees Before Top Dead Center on the balancer.

Why, oh why everything always seems so simple when done by others?

Went under the truck with a marker and… just don’t find any marks down there.

Am I supposed to see some marks there?

[Gary Lewis]

Am I supposed to see some marks there?

I see the timer and the notch that is probably TDC. And if you sand the balancer either side of that notch you should see other marks.

[BigBrother-84]

Am I supposed to see some marks there?

Ok, I did a little archeology, soft sand paper and brake cleaner.

Found it.

There’s a big notch at 0 and a smaller at 8.

[Gary Lewis]

Ok, I did a little archeology, soft sand paper and brake cleaner.

Found it.

There’s a big notch at 0 and a smaller at 8.

Ok, it looks like the big notch is TDC and there's a smaller notch at 8 degrees BTDC, which is probably factory timing. I'd mark the 10 degree notch and set my timing to that were I you.

[BigBrother-84]

Point the timing light at the balancer/pointer combo and you should see the white @ 10 BTDC.

It was setup at 12, I changed it to 10.

Now put the vacuum line on the vacuum advance and the timing should advance into the 20's and the RPM will go up.

It is what happened, the advance jumped by about 20, I would say (gee, how do you do to get and exact reading?).

I reduced the idle to around 800rpm (Yeah! I installed a tach for other reason than just “nice in my cluster”! )

Is this a correct idle speed?

 

[Gary Lewis]

Point the timing light at the balancer/pointer combo and you should see the white @ 10 BTDC.

It was setup at 12, I changed it to 10.

Now put the vacuum line on the vacuum advance and the timing should advance into the 20's and the RPM will go up.

It is what happened, the advance jumped by about 20, I would say (gee, how do you do to get and exact reading?).

I reduced the idle to around 800rpm (Yeah! I installed a tach for other reason than just “nice in my cluster”! )

Is this a correct idle speed?

They had it at 12 probably to compensate for not having vacuum to the advance. But going back to 10 will make starting easier and help prevent pinging.

And yes, when you connect the vacuum advance the timing will go up A BUNCH. But you won't get an exact reading as it'll be jumping around some.

There is no "right" RPM. At least not one everyone can agree on. Right is what you like, something that sounds reasonably slow and yet isn't so slow it is easy to kill the engine when taking off. I like 650 RPM, but that's on a 460 which has more torque at low R's than yours. So you'll have to adjust it to your liking, although 800 might be a bit fast.