VPV tuning

[jon_g9121]

Is there anyway to disable the Impco VPV when starting a engine? Mine immediately floods a cold engine so it wont fire. I tried using the different size nozzles it comes with but it doesnt seem to matter. Ive been having to vise grip the vacuum tubes to get my truck started in the morning and its getting pretty old. At the same time the VPV lets me get 15 mpg on the highway (pretty good for a 5200lb brick) and a significant increase in full throttle power, so I dont want to get rid of it.

Other parts in the system are a Model E and a Impco 200 mixer on a ford 300 I6

[storm]

Make sure you have the VPV connected on the secondary side of the regulator/converter. If you have it connected to the primary side you will most definitely flood the engine. Take a look at the attached picture to see where the VPV should be connected.

[jon_g9121]

There is only one port on the model E that isnt marked 'water,' so i think i got that part right. I drilled and tapped a 1/4 in air valve line in the venturi of the 200 and connected the 3/16 line to manifold vacuum on the front of the 200, as per the instructions I got from the folks at carbturbo.com.

heres a pic of the setup.

[C3H8]

Puzzling. The 200 mixers are notoriously lean so flooding using a VPV is rare. That being said assuming you have it connected correctly by using the indicated ports a small electric lockoff would likely solve your problem. You could use an IMPCO SV valve or small electric solenoid inline between the VPV and the mixer activated by an electric switch on the dash after start up. The SV would be ideal for weight and size, however I am not sure of it's durability with continuous power. Another alternative would be the Autotronics solenoid part # 4048. It is a three way valve however the third port can just be capped off. The 4048 is well suited for full time power activation. With small electric solenoids there are some inline gas solenoids used on older gasoline carburetors. These are metal and very durable and rated for full time activation.

[C3H8]

One other comment. I just looked at your picture. The VPV is set up correctly.
Your model E is oriented incorrectly though. The regulator outlet should be pointed downwards. In your setup oil residue will slowly build up in the regulator eventually affecting diaphragm operation. If you leave your setup this way you should check for oil build up regularly. The unfortunate part here is you will not be able to check build up in the primary section as your secondary port is at the highest location. To check the primary chamber you would have to take the regulator 3/4 of the way apart. Proper positioning should have the vapour outlet at minimum of 15 degrees below horizonal mounting or even vertical with the outlet at the bottom.

[jon_g9121]

I decided to mount the Model E upside down because it simplified heater hose and fuel line routing and offed a significantly shorter vapor hose connection than mounting it in the designed position. As for the heavy ends, I think taking it apart and cleaning once a year is a price worth the cost for all the other benefits.

I had no luck finding pn 4048. I sent Autotronics a request and we'll see if they get back to me

Any reason something like this wouldn't work?

https://www.amazon.com/4inch-Normally-C ... B00ON8XFSO

[C3H8]

Any solenoid like that would work. The reason I suggested a 4048 is they are very light. Another alternative is this solenoid shown on ebay.

https://www.ebay.ca/itm/SOLENOID-LOCK-O ... 100623.m-1

You don't say where you live but if your in Canada you can contact Proquip in Calgary for the 4048. If in the US you can contact Carb and Turbo in Minnesota or Nash Fuels. Lots of others also. Autotronics, also called Dual Curve, was a division of MSD. They closed that division about 10 years ago but MSD might still be suing that part for something.

The solenoid you show would work but it should be solidly mounted with a bracket if you go that way.

[C3H8]

The valve you show is vey economical. Great price. It indicates it is for air and will work on LPG probably. The seat material may not be completely compatible with LPG though and possible deteriorate quicker than a fuel rated seat.

[jon_g9121]

I ended up going with this guy instead.

https://www.amazon.com/gp/product/B07SP ... UTF8&psc=1

I figured a normally open solenoid would work best since I can wire it into my starter, so its only closed when cranking. Preliminary test this morning seems like it works very well, hopefully it stays that way.

Thanks a bunch for the tip

[C3H8]

Excellent choice. You carried the logic forward to a solution I didn't think of. Your valve will only have to operate momentarily unlike my recommendation that required continuous voltage and the inclusion of a switch. Thanks for updating us.