Six pack center tunable metering block

Anyone know the difference between promax
Vs quick fuels ?

EbG https://www.ebay.com/itm/Quick-Fuel-Technology-34-4QFT-Carburetor-Metering-Block-/322387823334

Promax

I think thats a older QF design, ive had that one in my center carb for going on 14 years or so.

I also think the new QF ones are slightly different.

Not sure of the PM unit but ive had zero issue with the qf item.

Why do you need a different metering block?

Id have to say because a well setup, well tuned six pack with some modern parts can be as responsive as if it were modern fuel injection, at least mine is.

May not be necessary
But would complement a lopey cam with a crappy
vacuum .

Dynoin a monster this week
Wonderin if a different center may yield some
different results , but probably not not necessary .

Just saw the coating on the promax and resiliency
to the new crap gas got me thinkin ..

Im about ready to go back to cork gaskets, the "nice" blue ones seem to soak up and bloat in short order these days.

Try the Superformance carb gaskets.

The Promax plates come set-up for your application ie you have to tell them your specs etc. Mine still needed a bit of fine tuning.

Both metering blocks have the idle fuel restriction above the float level. It should be moved lower which requires drilling, re-tapping and moving it to below the fuel level for more consistent A/F metering.

The black anodize finish is very durable. You really need an A/F gauge to be able to tune at this level.

If promax is gettin -150 to preliminarily tune
They can redrill , lol.

I agree on afr tool .
Makes a difference for sure ..

You would think so. Luckily, it's not that hard to do. But you do need good drill bits and a quality set of taps. Walmart, Harbor Freight isn't going to cut it.

Id like some more info on relocating these
Why doesnt quick fuel or promax know this tip ?
Without investigating, does anyone know how much higher the new blocks locations than factory location and just how much WILL it benefit relocation ?
During hard acceleration or always ?

The Promax block is a BLP, which you can buy in DIY kit form from BLP with either the high or low IFR location for about half what Promax wants. You do need to be able to drill all the replaceable jets as part of the assembly process.

Do you use the vacuum port the original metering block has? Neither the BLP or Quick Fuel/ Proform "race" metering blocks have that feature.

There is nothing "wrong" with the original cast metering block, other than lack of adjustable tuning circuits. What is it you think needs to be changed?

Nuthing wrong yet , just getting prepped and aside .
Car ran pretty good with last combo - but new engine
may need a little finer tuning .

Too bad on the lack of vacuum port , but nice internal coating and
diversity of tuning is a plus .
It looked like an inexpensive improvement that Id like to abuse myself with

you can drill and tap the original block for replaceable idle feed restrictors...if the motor needs it.
6-32, 1/8" long brass set screws if i remember correctly (google will turn up tons of hits).

The Promax is a 51241 BLP metering block with Promax laser engraving on it. My suggestion is order a 51251 metering block from BLP, it has the idle feed lowered. You will need plugs for the mainwells, mixture screws and seals, and gaskets from BLP. To finish you will need a box of 6-32 x 3/16 and a box of 6-32 x 1/8 brass set screws from McMaster-Carr to make your own emulsion bleeds and blanks (3/16), and for idle feed restrictors (1/8). A 61-80 drill index set, a pin vice, and a slow speed drill will get you drilling your own restrictions. All of this and still probably less than $150.

Thanks Mark. Can you explain the reason for lowering the idle feed restriction to those reading. I can't seem to find the old posts that covers the theory of why it is important.

It did make a marked improvement if my idle A/F ration stability on my motor.

(edit) Found it. I think this covers it...Don't neglect to click on the last link on the article. Note how long ago they figured this stuff out. Those guys were serious about making America great back then.

https://www.tapatalk.com/groups/racingfuelsystems/viewtopic.php?f=31&t=18

I think that article covers it
And since i dont anticipate low vacuum
Im not worried bout the relocate.

I did steal the metering block out of my
buddies quick fuel carb today

Its got ported vacuum and two less
on each side ..

The idle air screws are way better on this block

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