The Siren Board

Looks Great!

This looks great! The Regal Red really contrasts nicely with the snow!

jerrylovessirens wrote: ↑

Sat Feb 11, 2023 12:15 am

dat612freakoftoday wrote: ↑

Fri Feb 10, 2023 7:50 pm

Just wondering, Where was this originally located?

We are pretty sure it came off of the old Greede Foundry in Milwaukee.
1312 S 1st St, Milwaukee, WI 53204

Building is long demolished. Here is a street view from 2007 before it was demolished

Also included is a very grainy vintage photo of the roof. Might be older than the 1950s. I'm going to try to see if I can find a better photo.

Just think, our Mobil Directo would have been in that pile of rubble and scrap iron if it were not for Joe!

Well you are lucky you saved it before it was turned to scrap

Got the repaired and painted battery box installed. It sure looks great!

Got the first coat of paint on the air cleaner. I have a feeling I may have to wet sand once on this.

This project has been coming along nicely.

Got the painted aircleaner loosely installed. Got the United decal installed. Looks good

While I was inspecting the oil bath cup, I noticed daylight showing through! A couple really small rust spots must have blasted through. Mixed up a small daub of JB kwik weld and spread it on. Not perfect, but it works!

Started to fabricate the throttle solenoid mount. It's coming along nicely. I'm designing it with plenty of adjustment so we can get the thottle pull just right!

I did a Saturday test of the siren. We are getting really really close to dialing it in. I can only run it at full speed for about 10-15 seconds as a courtesy to my neighbors.

We are getting so close to completion I can taste it!

First, I found that there was no way to successfully silence the siren with the projector on. There was too much air exchange from inside the donut through the gap in the intake, that no amount of pillows or cardboard could seal it off. So off went the projector. I then duct taped a exact fit piece of cardboard over the stator. This effectively silenced the siren to a point where the VF4 is louder than the siren itself.

I was then able to tune the governor linkage to give a steady RPM at close to 3000rpm. There is still a little bit of surging going on, but it is not terribly noticeable in the tone of the siren itself. One disadvantage of the Stromberg carb compared to the later Zenith, is that it does not have a high speed adjustment for the jet. It is a fixed orifice.

I will leave the projector off until the throttle solenoid is installed and adjusted properly.

I also got the air cleaner fully assembled and filled with oil. It sure looks great.

The right house cover has also been test fitted. I will be making up the stencils soon for MOBIL DIRECTO SIREN, as all the early Milwaukee ones had.

Looks good Jerry! Also, when the governor linkage is fully tuned up, will it run at the full rpm steadily without any noticeable pitch changes?

Lots of progress, can't wait to see it with the painted text. It is important to account for the lowered air resistance during tuning, as it can result in the siren running slower than intended after the restrictions are removed. Best to shoot for 3450RPM for optimal results.

Synther wrote: ↑

Mon Feb 27, 2023 2:57 pm

Lots of progress, can't wait to see it with the painted text. It is important to account for the lowered air resistance during tuning, as it can result in the siren running slower than intended after the restrictions are removed. Best to shoot for 3450RPM for optimal results.

The VF4 is not designed to run that fast. I spoke to the nation's premier Wisconsin service station here in Milwaukee, and the VF4 is rated at only 3000rpm for intermittent duty. Continuous duty max RPM is 2500Rpm, so we are already pushing the envelope. The Mobil Directo manual itself states a running RPM of 3000. This would give a tone of 400HZ.You will notice all electric converted 8 port Mobil Directos will run at 468hz or therabouts due to the higher speed of the 3450rpm electric motors.