You are right, a factory stock doesn’t deliver for a modified engine. Yes, we offer recalibration service for our customers that change their engine builds. We do that all the time and saves them money!
Do you double dog dare me? I completely believe you and anyone else who has said that it's not the ideal carburetor for a single plane. But I also believe that coming from someone who builds and mods quadrajets as a living that one could be optimized for such an application and am not gonna just dismiss what he says just because most others disagree. That's why I posted the question because it seems like it would be a mismatch with a Quadrajet so I was curious if anyone had used that setup. Although I do remember Steve Dulcich ran a modded thermoquad on his built up Mopar muscle truck with a single plane (not sure if he still uses one though). So I will probably end up with a double pumper 750 when I go to a single plane but I might just keep the ported (heavy SOB ) iron intake and run a quadrajet for awhile as well. Just playing out my options.
Hey do you have any pics anywhere, I would love to see that! What blower did you end up using? Did you build your own manifold or modify one?
Go ahead, dare to be faster! And better street driving ability. And better fuel economy....... There are plenty of decent carb options, and some bad ones. Plenty of Quadrajet haters. I love to line up beside them at the track. Cliff has done pretty well there too!
Like almost everyone else has stated...I tried to make my Qjet work on my SP3 and it was a turd no matter what I did. Bolted on a square bore double pumper and haven't looked back since. I'm sure that a Qjet CAN work...I just don't see why going through the trouble is worth it.
Many have to do simple mods to the Holley types to get them to work right. Just different kung fu is all.
I bought the 650 12 yrs ago(really wanted one of the big 2 bbl carbs) to run on the d/p..... and the s/p........and now on a 4-71. have not change anything on the carb. tighten the screws and bath it on the outside every once in a while. getting old. don't want to work to much on it. lol
I, as I am sure others have absolute success with a Q-jet on the 455 SP1 intake. The Q-jet is what I drive around with when not at the track, and there is no sag, hesitation, or flat spots anywhere, it is seamless. Having said that, we are not talking about a 455, or the SP1 intake, we are talking about a new single plane intake on a 350, and while the SBB is a great engine, it isn't a 455. I think it can work, but it probably needs a different calibration than the 455. Someone like Mark, Ken, or Cliff, needs to do some experimentation with an SP3 equipped SBB 350.
My q-jet is sitting in a box where it belongs, with my other numbers matching parts. I do run one on my boat, but it's not for performance, just trolling and to & from hot spots! Yes it falls flat when floored, always has from day one.
My Q-Jet ripped ass on my Stage 1 intake, not so much on the SP3 My AED 850 DP rips ass on the SP3 My theory and I'm no carb expert by far, is the moment the secondaries slam open on the QJ, theres no fuel for the transition to WOT for that split second to cover the big open hole, and I believe the secondary pump shot makes all the difference on the double pumper carbs. When I swapped to the AED carb, I could slam to WOT from a standstill or whenever, and the response was instant
Again not a 350 but a 455. I’ve only had it out once since installing the SP1. I didn’t mash it to the floor as hard as I could but did push the gas pedal down to the floor in a quick fluid motion and noticed no hesitation at all. It’s a level 3 Quadrajet from Mark. Next time out I will mash it down as fast as I can and report back how it goes. I’m no expert, just another guy that likes Buick torque. Cliff
To prove what? Like any professional, I'm sure a check would expedite the results sought after. Qjets being so application specific for something very different requires more than the turn of a couple of screws. If a fellow isn't prepared to handle more than that or buy a modded one, don't bother. The double pumper types are much closer from the factory. I know what you meant by that Larry, just using the quote to illustrate something.
Use a Cadillac accelerator pump. Open the poe holes to .055 or more and counter sink the opening slightly to clean the edges. Limit the air flap to 80 degrees, NEVER straight down 90 degrees. Notch cut the air flap like Ruggles shows in his book. Try different vacuum diaphrams from .75 seconds (like mine) up to 2 seconds duration. Take a file corner and dig cross hatches on the flap where the brass tube hits the flap (takes one minute) Use 3/4 turn on air flap tension and go from there. If your sucking cold air, the air flap needs tension! Let the intake manifold warm up to 100-120 degrees minimum. Experiment with this. Using a 9" 3500 stall converter. I use 14 degrees initial timing and curve the total to 4000 rpm, not any less. "Revs like a sbc race car. Spent many hours on my q-jet. Just sharing my results. Using a B4B and spacer. * Criticism is welcome, since I know there is more yet to learn.
Ok Not saying a Holley wouldn't be better or even easier. Ken hooked me up with a well built Qjet and I ran it. Worked extremely well, no hesitation at any RPM, have a thread about it somewhere I think. People said you couldn't use JB weld on an intake yet you have proven otherwise. Seen it in person as a matter of fact. I do not understand why you would tell anyone that something is impossible when your builds have lived outside 'the box' lol. Edit again: I get how the additional pumps in the Holley would be beneficial. To the argument of others that was something I never tried. However, swapping from the aluminum dual plane to the SP1 made me a very happy driver. I need to dig up my time slips.. with my luck the new owner has them. After the swap I couldn't make a full pass due to a fuel pump issue but there were 1/8th mile results. The car was not an ET chaser, it was made to go fast on the pavement and the 1/4 mile times were what they were. Last note: If i had to do it again.. it would be EFI.
So what is the opinion on running a vacuum secondary? Or does everyone only run mechanical secondary holleys? I realize that all the previous posts were about double pumpers but do you believe that a holley is always better or do you just justify it for the secondary shot in this scenario?
What are the popular opinions of bias ply tires vs. radials? Does it matter if the tires are black vs. any other colors? (sarcasm for relevancy sake) Are you looking to purchase a ready carb or build one? What is your budget or tuning skills? How close do you need it to be in order to tune it close enough to be happy? Is this a time vs. $$ question? Have cores of any types to work with? Even the vacuum carbs aren't created equal. Holleys after a certain design change decades ago having even the same size designation as modern versions have some obstacles to surpass requiring drilling and resizing orifices to equal their earlier iteration.
Obviously black tires are the fastest. Unless it's on a Thursday afternoon above 70 degrees, then you want red tires . I get where you coming from and understand your point that it does come down to a what do you want and how hard do you want to work to get it there situation, as does literally everything. I was more posing the question out of curiosity of what people run and there experiences with such. Might be beneficial to whoever reads it, might not, who knows.
