[Skip Fix]

Since I never answered went out and measured the "bigger" primaries 1.425-.430 vs 1.375 for a standard 800 CFM Qjet, Urban also thinned shafts also . The bigger butterflies had a 103 stamped so probably some Holley.

[PAUL K]

Originally Posted by Skip Fix

Since I never answered went out and measured the "bigger" primaries 1.425-.430 vs 1.375 for a standard 800 CFM Qjet, Urban also thinned shafts also . The bigger butterflies had a 103 stamped so probably some Holley.

You just have all the cool stuff!

[70GS455]

Originally Posted by Skip Fix

Since I never answered went out and measured the "bigger" primaries 1.425-.430 vs 1.375 for a standard 800 CFM Qjet, Urban also thinned shafts also . The bigger butterflies had a 103 stamped so probably some Holley.

Was that measured at the butterflies? Or venturi? If butterflies, how was the taper back to the venturi handled?

[Skip Fix]

Measured at butterflies, I do not think Venturi area was enlarged, I'll crack them open and check the transition form the body.

FWIW I did use the carb on my RAIV 400 in NMCA racing and no difference in it and a regular SR 73 SD Qjet but until I switched to smaller headers and a reverse split cam the RAIV heads had some reversion issues and both those picked the car up . I id run it on my first 455 Ehead roller motor on my HO intake in the TA to keep the Shaker until I found an extra base I could modify to use a Holley/Demon(Demons actually have a smaller fuel bowl adjusting screw). Swap at the track with a square bore to Holley adapter and a 850 Demon DP picked up 0.3 seconds! An eventual swap to a Torker II picked the car up even more and improved the idle with the single plane. So for ported Eheads and a roller cam even a ported HO intake was a restriction.

[hojs69]

Does " shaker455" still frequent the forum?

This was an interesting endeavor. Would have been great to see the final results and conclusions.

[tempest1964]

If you click on the persons forum name (in one of their posts) it brings up their info. I just looked. Looks like he was on the forum on 1/4/26. If you have a question, he will probably answer. Either post it public on the thread, or PM him. If it’s about the modified q’jet, I hope you post it on the thread. Good luck

[hojs69]

See post #79 and #80 in this thread.

[tempest1964]

Oh well. Try to do a solid

[shaker455]

Hi, I'm here just been looking for the last pics & vids as to where I had left off on the project.
Looks like I had stopped on the project Sept of 22'
Back then, When starting into live testing the mods to the venturi & booster had affected airbleeds and they're location.
I had considered starting over with a single main airbleed unit as better airbleed placement but I was able to over come the issue.
In short I did not match my factory single ring 71 455HO in booster signal and it took much more jet size to compensate.
I did drive on it and again primary throttle response did not match my factory unit.
Biggest difference was WOT, it spun the car out!
last time that happened like that was with an 1150 dominator!

[grandville455]

Was this originally a 750 cfm Q jet and you ground the rings off, changed the booster design and milled out the ring in the venturi and it still wasn’t as good as the stock 71? So was the WOT better than the 71? What do you use to get inside there to grind that ridge out? Do you think taking the ridge out it lost velocity? Thanks!

[shaker455]

Originally Posted by grandville455

Was this originally a 750 cfm Q jet and you ground the rings off, changed the booster design and milled out the ring in the venturi and it still wasn’t as good as the stock 71? So was the WOT better than the 71? What do you use to get inside there to grind that ridge out? Do you think taking the ridge out it lost velocity? Thanks!

You can read earlier post for your questions:
Post #1 outlines parts used
Post #35 milling machine
Post #76 base plate throttle bore resizing, milling machine
No mods to venturi shape
When outer ring is removed drastic signal loss
Area was much larger than a 455HO casting so signal loss maybe greater
Definite increase in area WOT, others who have done this mod street & strip can confirm
Goal was to regain some signal strength to match the 455HO while gain primary airflow and low speed drivability
This lead to three other approaches that I started to experiment.
If you take a try post up your results
Thanks

[grandville455]

Originally Posted by shaker455

You can read earlier post for your questions:
Post #1 outlines parts used
Post #35 milling machine
Post #76 base plate throttle bore resizing, milling machine
No mods to venturi shape
When outer ring is removed drastic signal loss
Area was much larger than a 455HO casting so signal loss maybe greater
Definite increase in area WOT, others who have done this mod street & strip can confirm
Goal was to regain some signal strength to match the 455HO while gain primary airflow and low speed drivability
This lead to three other approaches that I started to experiment.
If you take a try post up your results
Thanks

Thanks! So looking at this pic, did u remove this ring also? It kind looks like it in the pic?

[shaker455]

Originally Posted by grandville455

Thanks! So looking at this pic, did u remove this ring also? It kind looks like it in the pic?

Yes

Later experiment I had machined a 750 venturi to an 800 leaving outer ring in place like an SD-455 casting.

[grandville455]

Originally Posted by shaker455

Yes

Later experiment I had machined a 750 venturi to an 800 leaving outer ring in place like an SD-455 casting.

How did that work,That’ s funny I’ve been thinking of doing the same but to a 800! I don’t have a mill tho �� so it will be by hand

[Skip Fix]

Factory boosters have a step like that or did you machine it Jeff?

[shaker455]

Originally Posted by Skip Fix

Factory boosters have a step like that or did you machine it Jeff?

Skip, I machined up a 750 casting to 800 venturi specs

[Skip Fix]

The bottom of the booster looks like a stepped Holley down leg vs a regular down leg.

[shaker455]

Originally Posted by Skip Fix

The bottom of the booster looks like a stepped Holley down leg vs a regular down leg.

Skip, I'm referring to the last two pics I posted in post # 93.
That has standard non-modified boosters.

You must be talking about some of the booster extension I had machined and installed.
Yes I incorporated a shear step in the booster but slimmed down the outside design.
Thanks

[grandville455]

Originally Posted by shaker455

Skip, I'm referring to the last two pics I posted in post # 93.
That has standard non-modified boosters.

You must be talking about some of the booster extension I had machined and installed.
Yes I incorporated a shear step in the booster but slimmed down the outside design.
Thanks

What’s the most power you or others have made with one of your qjets?

[70GS455]

Originally Posted by grandville455

What’s the most power you or others have made with one of your qjets?

My 800 cfm Qjet is currently at 610 ft lb, 600 hp.