Barrel Valve Leakdown thoughts...

Wizbang and I were having a discussion last night on barrel valve adjusting.

We differ a little on our methods, but we both get to the same place.

So, while on the toilet (where I do my best thinking), I had this brilliant idea, which he thought would work (I'm looking for someone to shoot it down with logic).

Instead of setting the valve at "X" leak down, rapping the motor for best response and re-adjusting the BV, then leaking it down again, and recording the weather and percentage, why not use a wide band o2 gauge?

Use the same methods that have been tried and true, and see if those methods result in the a/f gauge giving the same a/f ratio number each time (or really close). If it does, pick the average number within the range that works best, and set the BV for that a/f ratio at idle.

Would this work? If not, why not?

It seems like it would save some time in the pits.

 

Dammit Jim! LOL

 

straining is hard on the brain

another brillient thought flushed away like mike said idle has nothing todo with afr. you want it fat. ever notice the amount of fuel puking out at idle on a screw blower car? take that away and youd melt it down.

 

I think you're misunderstanding me.

I'm only wanting to set the idle A/F ratio.

And yes, maybe on a pro-mod you'd melt it down, but not on the pussy hp I make.

 

if its a chevy you still dont want it to burn up on the idle just set it with the leakdown tester at 80-84 percent i have mine at 82 percent and letter eat lol
for and old chevy 76-80 percent to lean and it will stumble when you crack the throttle

 

That much? I was going to start at 70%... Maybe I should re-think that.

 

Wait a minute. After further thought on that statement...

Your BV leakdown isn't going to be the same as mine.

Number of nozzles, base system pressure, blower size/style not to mention a few other things are going to contribute to some differences.

Right?

 

leak down bv

set it at 75 warm it and try to rev it if there is a mark in the spool valve shaft set it at one o'clock fire it and try it how did they do it before leaker's there is no exact science from one setup to another crank on it till it feels good and give it one more flat and run it if see is squirtin a little you are close just my 2cent

 

WJ i have run blown chevys in 47 fiat altered for a long time before i went to a hemi i wouldnt steer you wrong are give you bad advice if i didnt know i wouldnt say any thing ( lol ) besides i paid alot of money for some of this knowledge but some of it i learned the hard way because i didnt have ayone to ask

 

Thanks Jim...

Here's a little shot of the finished fuel line plumbing...



The passenger side pump, yet to be plumbed, is a transfer pump from the rear cell to the front surge tank.

 

WJ....fly with Jim's advice...And one other thing if stumped....call Mike Canter..Dave
www.myspace.com/daveloweswr

 

Afr

Another thing to consider is idle fuel volume is a function of both BV leak AND idle check valve pressure. If everyone is running the same check valve pressures then stating a given BV leakdown to suit a certain combination is fine.
Jim

 

Will,

Thanks, but I run the blower restraints like I do my own seat belts. Really damn tight.

Something that Mike Canter PM'd me about, which I appreciate, is that I don't have a check in the pump sizer circuit. Mike stated it should be around 40 PSI (sorry if I'm giving away secrets Mike, but I'm trying to learn here).

This was good food for thought, and made me think further on the topic. Just for giggles, I called Jim @ Enderle to get his thoughts as well. Jim stated that they typically set them up at 25PSI.

I guess I'm still a bit confused on that particular subject. I thought the whole idea of a pump sizer was to reduce the total output of the pump at ALL RPMs, not just above a certain pump pressure.

I can logically see having a check in the line set just above the idle pressure check (6-8 PSI) to keep the BV line from leaking down to nothing, but I'm struggling with the logic behind having it at 25 or 40 PSI.

_______________________________________________

On a secondary topic... Room up front is really limited, without stretching the nose of the truck, which is not going to happen this year.

I have a 1 Gallon aluminum cell measuring 6x6x6 that will just fit on either the driver or passenger side of the motor, in front of the mid plate.

This brings in a concern about rules and safety. If I create a full length blower belt guard (similar to the RCD unit) down the driver's side, can I mount the 1 gallon cell legally between the belt guard and frame rail?

 

idle %

maybe a flow meter would tell idle gpm or %
i purchased one but havent used it yet
any one know what idle gpm should be on a
60 over brad fuel head 526/littlefield1100 pump/ combo
im 85% leak down now

 

will that old truck take all that motor ( lol ) looks pretty good there wj

 

Prolly not... I hope not. I only want to run mid 7s.

 

mag

I bet you started sweating when you put the mag in it looks close to the bar nice looking set up looks like you have done a lot of work