Milest

Last year I purchased an Edelbrock Q-Jet # 1901 (750 cfm) for my 72 L-48 and installed with a performer intake. The stock jet and metering rods are as follows: Main Jet .069, Metering rods: primary 36B, secondary-DR (from Edelbrock web sight).

The car runs great, but I have nothing to compare it to. All the many threads that come up here on Q-Jets and with minds like Lars available I thought I would inquire to what could be done to improve my current setup.

Thanks

Phlash

See the post on Qjets vs. Edelbrocks. Lars just cleared this one up today for me.

Phlash 72 BB Roadster :seeya

Corellian Corvette

Milest - I have almost the exact setup on my '73! Check out my web page!

Phlash -- can you send me the e-mail that lars sent you about the differences? It's not posted on the string unless I'm looking at the wrong string...

Thanks!

PRNDL

Lars suggests that the later style (75 and up with electric choke) Qjet can benefit from stepping up the jets to use with the "truck type" rods. I think that's what he said! But we all have the #1901 Edelbrock Qjet which has a divorced choke. MJ
http://forums.corvetteforum.com/zerothread?id=241990

Phlash

Corellian,

You got mail!

:seeya

Phlash 72 BB Roadster

Phlash

My Edelbrock is a 1904 electric choke. My 72 LS5 lacks top end performance, but I think Lars may have given me the answer. Only about 60 minutes and a hand full of jets will tell.

Phlash

Corellian Corvette

The reason that I asked was because, according to the specs, it looks like the 1901's have the same jets as well. Since I seem to have a lack of power at WOT, I thought the same scenario may apply.

PRNDL

So what do we do? Can I buy a set of alternate jets (and rods?) from Edelbrock? Sounds like fun! :) (I also have a new #1901 Qjet replacement)

MJ

Phlash

I checked with O'Reilly's Parts house, and they carry some but not 74's and up. However they are willing to get whatever sizes I want. Could go to Chevy Dealer too, they might still carry them.

Phlash 72 BB Roadster :seeya

Ganey

Didn't Lars do a jetting paper for you guys? Have not read any of his papers. Have purchased jets from the Chevy dealer. On the pri., you can go to larger jets or smaller rods. Stock jettings for your engine are a good place to start. Roe's book rec. for mods. Just recently scanned in rods & jets for someone on the forum.

Phlash

For high rpm you need more than stock cam.

:cool:

Phlash

True, but right now I can only get 3700 before it peters out. I should be able to easily take it to 5000 stock. Note, this is a new carb with a newly rebuilt stock engine. There is only about 1000 miles on it yet it was rebuilt 4.5 years ago.

Phlash 72 BB Roadster :yesnod:

Ganey

Have you checked that sec. open? Sec. will not open w/ engine cold unless sec. lockout on pass. side has been bent out of the way.

mountainmotor

Phlash,
Check for kink in fuel line or collapsed line from frame to fuel pump.Have you checked that carb is opening all the way by putting gas pedal to floor and checking by hand that it is fully open?

Phlash

Now question the secondaries are opening. I have an old style open element air breather. It is possible that the line is collapsing, but there are no kinks. The hoses are in good shape though. It feels like it is running out of gas (literally). I am hoping to try the jets this weekend and see. It is suppose to be 75 degrees tomorrow.

Phlash 72 BB Roadster :yesnod:

Tominator

I'm running the 1406 600cfm performer, somewhat different from yours, but these are my results so far.

Stock setup; seemed like it was starting to get fuel starvation a little after 4000 rpm, primary jets .098, sec jets .095

Modified; put .101 jets in the sec. and it reved somewhere around 5400 - 5600 rpm before it started get fuel starvation.

Going to drop in .104 jets in the seconday and hopefull it run past 6000 rpm.

Still going to play more with power springs and rods.