Furious65
C-body Guy
It appears he has put out a vid addressing some of the critiques and concerns people have about his carb cheater. I think he has some valid points.
Carb Cheater - What Say Yee?
- Thread starter Kmrumedy
- Start date
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Thanks. You just told me enough for me to know that he doesn't have a clue.
Chasing WBO2 numbers is pointless unless they've been related to something useful, and AFR numbers even more so.
Well, the power valve is for enrichment of the power circuit. Hence its name. WHEN do you want that enrichment? Holley says cut the idle vacuum in half and choose the closest valve to that half vacuum reading. Why would you want enrichment to the power circuit at such a low vacuum? It's the power circuit. I get a vacuum gauge connected to manifold vacuum with a hose long enough to get the gauge inside so I or my passenger can read it at cruise speed. I get the cruise vacuum reading. In other words highway speed with barely enough gas to keep it t speed. The vacuum reading will be highest then. I take "whatever" that reading is, and choose a power valve a couple of numbers lower. That way, the power valve is actually opening when it's time for power circuit enrichment. When you get it about right, you can feel when the power valve opens. After tons of reading on forums and magazines and such, I tried experimenting with it and I found that that's the way that seems to work best for ME. You will also be able to drop the main primary jet sizes down some, since the power valve is now opening during cruise enrichment and that can even pick the mileage up some.
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Isn't that the same guy that put a weedeater carburetor on a car engine?
Yes it is..... that's why it's such a glowing endorsement
I wasn't makin fun of him......that project actually worked much to my surprise and probably to a lot of other peoples surprise too. lolYes it is..... that's why it's such a glowing endorsement
It's ok... i'll make fun
he's actually a decent guy.. i had a friend that did like a dirtbike carb on a car in the 80s trying to get amazing milage... he also ran a fuel regulator crazy low... like that mattered.. people do weird things
This is the better way to approach it for sure.
At least for us mortals.
One step fancier, but not exotic (ie. 5 gas analyzer combined with a load dyno) is datalogging MAP and acceleration.
Every decrease in vacuum with more throttle should result in more power.
I've posted a couple of snapshots where I did that.
Here's one, which does not make it to the enrichment point in part because too much timing.
Its difficult to "crowd" a vacuum long enoguh to get good readings. Better way would be on a closed course, starting from the same speed each time.
We've also discussed the theory a few times here.
Power Valve Selection: The Definitive Answer
There are varying opinions on how one goes about selecting a power valve for Holley based carbs (as anyone who has worked on one well knows) There's the 1/2 of idle vacuum, either with 4-speed in neutral or auto in drive, the more widely accepted 2" less than cruise vacuum, I've also seen people...
www.forabodiesonly.com
I can give you one of the best examples of that. Doug Dutra. Were it not for him doing "weird things", we'd not know a lot about the slant 6 that we know today.It's ok... i'll make fun
TT5.9mag
Two atmospheres are better than one
All his crazy little device does is control the amount of air (signal) the carburetor sees. The reason he needed it, for his lawnmower carb thing, is because he couldn’t jet the dumb thing properly to match the fuel to the air. And I doubt the lawnmower carb had enough circuits to maintain an afr through a range of throttle openings and load variations. It’s unnecessary with a properly sized carb and some decent tuning skills.
MopaR&D
Nerd Member
I'd be interested in running the Carb Cheater if I still lived in a place with lots of altitude variations. But I was able to successfully tune and run a carb anyway. Probably would have saved some gas when I drove my D200 up into the mountains to go camping to swap the metering rods in my 1406 but whatever, thing can barely manage 11 MPG anyway. 360 in a 3/4-ton frame, aggressive 33x10.5" all-terrain tires, 727 trans, Dana 60 with 3.54s, aerodynamics of a shoebox and frontal area of a barn door.
Street Demon is a great carb btw I also love mine. Only weakness is it starts to have trouble keeping up with fuel demands at higher RPM on hotter engines but that's obviously not what it's designed for.
Regardless of opinions on the Carb Cheater, Thunderhead289 is quite proficient at carb tuning. Very smart guy and has an intimate understanding of how they work. His videos on tuning are worth checking out.
Street Demon is a great carb btw I also love mine. Only weakness is it starts to have trouble keeping up with fuel demands at higher RPM on hotter engines but that's obviously not what it's designed for.
Regardless of opinions on the Carb Cheater, Thunderhead289 is quite proficient at carb tuning. Very smart guy and has an intimate understanding of how they work. His videos on tuning are worth checking out.
Thanks gents. I wanted to ask for Rusty's method earlier, but I didn't want to muddy the OP's thread. I'll study up a little more in detail, but the car in question that I'll be testing this on has several other issues that need attention before getting to the power valve.
I apologize if I did that, but I was thinking it was kinda all related so I threw it out there. If it's too far off the beaten path, just ignore it. LOL
I don't think you did that. Either way, your explanation and the links posted give me more than enough to go on.
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