PMO Installation 3.0sc 46MM Fuel routing question

[brentrussell]

My 46mm carbs arrived some months ago and I've finally got around to the installation.

The PMO instructions are very average in my opinion... lacking quite a lot of detail around a number of items... used many of the threads on here for help with it.. great!

My question re the Fuel line routing... all good up to the PMO Regulator, there is two threads out which I previously assumed they were for each bank but now I think one goes as the feed to one side then it goes across to the other bank and then out and into the other thread as a return line. Does that not favour the supply to one bank more than the other? or is it ok because the carbs only pull what is required?
Is that correct?




Look forward to hearing what is the correct method.

Brent

[brentrussell]

I should also add, this is a 73 car with a return line to tank using the original CIS High pressure Fuel pump.

[KensTargaS]

The PMO reg. / fuel should be at 3.5 psi to carbs . Top left is fuel feed - two on right is the feed for each carb. The bottom left connection is the return to the tank.
Not sure why you have outlets on the carbs "fuel rail". that regulator is set up for return to the tank as it's way of adjusting and regulating the fuel pressure. Wish I had more to offer. Have the same set up with Weber but no return off the carbs. '

I'd cap off each end of the carbs where your finger is & try that.

[LJ851]

The PMO regulator is just a flow restrictor and is designed to dead head into each carb. The other way to plumb it with fittings like on your carbs is to run fuel pressure through the carbs in series with a conventional regulator after the carbs and get rid of the pmo regulator.

[scootergt3]

the two fuel lines on the carbs pointing at each other are a cross over/ballace line ( connenct both with a fuel line.

[brentrussell]

Thanks Team.

Also had a reply from Richard Clewett who I purchased them off, he confirmed there is two supply feeds from the Regulator, the other outlets off the carbs are a crossover, PMO confirmed it can be run without but guarantees fuel supply on long hard cornering.

The PMO Regulator/ bypass does the return feed/ pressure adjustment prior to the supply it seems.

[Gordo2]

Hi Brent - got your PM.

I think your questions have been answered here, but thought I would chime in on the subject of using a fuel cross over vs. plugging the end of the fuel rails (which I did, and I believe most users do).

Using a fuel cross over between the carbs seems a bit pointless - but others may feel differently.

The output of the PMO regulator provides an even flow of fuel to each carb bank. As such, I have a hard time imagining a scenario where it would be beneficial to push fuel from one bank to the other via a cross over.

I suppose if you had 2 in-line fuel filters installed between the regulator and the carbs (some people run this kind of filter config), you could have one filter clog and still receive sufficient flow to both banks via a cross over.

To me - it's just more clutter, another potential leak point and additional component to remove when you take the carbs off.

Good luck,

Gordo

[mikedsilva]

I wouldnt mind getting my hands on a set of pmo carbs

[snbush67]

Originally Posted by mikedsilva

I wouldnt mind getting my hands on a set of pmo carbs

If you want to make the trip you can touch mine. Base charge is 5$ for 90 seconds… that’s supervised with the lights on.

[Hulley]

Originally Posted by snbush67

if you want to make the trip you can touch mine. Base charge is 5$ for 90 seconds… that’s supervised with the lights on.

lol!

[Jeff Alton]

It is pretty straight forward. You can see in this pic, out of PMO regulator block to carbs, balance feed between carbs, then return out of regulator block. On this 3.2SS we had not finished the return line plumbing when the pic was taken, but it does show routing. Hidden behind the bank 1 carb is the 10 micron billet fuel filter as well. Yes, we changed all the fitting to AN in black.