Holley 800DP vs Osborne Q-Jet

I am building a 470hp-500hp 70 455, ported iron heads, Performer or SP-1 intake, 4 speed, 3.42 gears, headers, MSD ignition. There is an 800 Holley for sale here
http://www.v8buick.com/showthread.php?p=825499#post825499
I am wondering if this carb will work well, will it bolt on? or am I better off sending my quad to John Osborne for a rebuild?
Thanks
Tim

 

In my opinion it's going to be a toss up; I think John's prices on rebuilding an existing q-jet are right inline with the cost of the Holley. Both the q-jet and the Holley 4165 are spreadbores, so they'll bolt on the SP-1 (TA 1207), Performer or B4B. My preference for mechanical secondary carbs would have me choosing the Holley, but that's me.

Advantage Q-jet: With John's work the carb is tailored to your application. Also more of a stock appearance with B4B or Performer.

Advantage Holley: The Holley uses off the shelf Holley parts for tuning & rebuild, available just about everywhere. Mechanical secondaries can be an advantage depending on how well the q-jet is set up. Accel pump shooters & cams can be tailored for your combo. Most manual cars I've worked on really liked the double pumpers.

I don't think the Holley's bigger accelerator pumps will make much difference with your combo. I would have said it's one more advantage if you'd been running a heavy automatic car with taller gears. I must say I do prefer mechanical secondaries, but it depends on how well the whole combination is setup as to whether they work to max effectiveness or not.

Also I have to add that I've heard very good things about John and his q-jet work.

Devon

 

Devon, great info thanks. How do you like your SP??? Did all of the linkage bolt on?
How is your low end, midrange?
Thanks
Tim

 

Tim, my ST400 is a full manual, so I don't have to worry about the detent switch anymore. I control the stall speed from the column shift, and the original microswitch on the throttle linkage keeps it in high stall when the throttle is closed. Adapting the original VP/detent switch to a Holley would be pretty straightforward if someone wanted to do so.

I run a lot of initial ignition advance which helps the big cam/carb/intake with the lower end. Car idles around 900 rpm in gear, high stall. The Barry Grant Silver Claw is a pre-Demon Holley derivative, 1000 cfm double pumper. I run the big 50cc accel pumps on both front & rear due to weight & 3.07 gear. The car is sluggish off-idle in low stall, makes for easy city driving. The switch is always at my fingertips if I need it.

Depending on traction & temperature, if I leave it in low stall and mash it from a stop (12-1300 rpm stall), it will most likely bog badly, even backfire...I just don't do it, no reason to. In cool air it will sometimes survive the low stall and light the tires as the rpm's come up. If I start out bringing the rpm's up a bit in 1st gear to 5 or 10 mph, it will take a full throttle romp in low stall with no problem and lose traction. It will do the same from 30 mph.

At high stall, with full throttle it will annihilate the tires from just off-idle.

Midrange & top-end are awesome as you might imagine. Full throttle at anything over 2800 rpm or so and I have my hands full.

The nice thing about your combo is that with the manual 1st gear ratio and rear end gearing, even if you launch at a low rpm, the engine won't be down there very long. I think you could easily take advantage of the super fast response a well tuned double pumper can give you. One advantage you'll have over me, with either q-jet or the Holley 4165, I think the small primaries will give you better throttle response than a similar sized squarebore carb.

Hope that helps...maybe you'll hear from another four-speed/3.42:1 person with double pumper experience. My experience in that regard is with lighter cars, Corvettes mostly.

Devon

 

Thanks Devon, what about a choke for that 4165? I don't see any linkage, is it fully manual?
Tim

 

That's a tough one, List-6211 looks like it was originally intended for 1965-70 Chevy 427-454 engines, probably the old-style divorced choke. Might take some work to adapt it to a Buick manifold setup.

Personally I haven't run a choke since the mid '80's when I switched over to Holley for the first time. I prefer to let the engine run until my "cold" light goes off anyway, so by the time I'm ready to drive a choke would be mostly open.

By the way, I remember installing one of these 4165's on a friends well built 350 Buick (back in 1987?), the 650 cfm model. We achieved high 13's without too much tinkering. He didn't run the choke either.

Devon

 

FYI, here's more on the 6211:

http://www.pirate4x4.com/tech/billavista/PDFs/New Jun 2003/holley numerical listings.pdf

Devon

 

just look at some nhra super stock classes. you'll see plenty of qjets running on 9.20 cars. remember is S/ & SS/ classes you cant do much to these carbs

 

I am a lifelong member of HHI(Holley haters International) Our annual convention includes the crowd favorite Holley shot-put contest. :laugh: Will take a good Q-jet anyday unless it is a pure racecar.