Re: thermoquad VS. Holley 750 DP
[Re: Performance Only]
#1031724
07/14/11 01:33 AM
07/14/11 01:33 AM
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Joined: Jul 2008
Posts: 30,632 Florida STAYcation
IcorkSOAK
Financed his waterbed
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Financed his waterbed
Joined: Jul 2008
Posts: 30,632
Florida STAYcation
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Quote:
if ther A/F ratio is the same for either carb, can you please explain why one will get better mileage over the other? same amount of air, same amount of fuel.
BECAUSE the TQ does a BESTer job mixing air and fuel on the primary side than any other carb out there. Just-like EFI does a better job than any carb.
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Re: thermoquad VS. Holley 750 DP
[Re: DaytonaTurbo]
#1031726
07/14/11 08:10 AM
07/14/11 08:10 AM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Quote:
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The TQ or QJ will still win over a squarebore carb, smaller primary bores get better mileage if the AFR is the same on both carbs. & you can make a 750dp get right at the same mileage as a 3310.
if ther A/F ratio is the same for either carb, can you please explain why one will get better mileage over the other? same amount of air, same amount of fuel.
the one thing i could never get used to on a spread bore carb is how much further you need to push the gas pedal in normal driving to get the same acceleration as a square bore carb.
The smaller venturis are supposed to be more responsive to small changes in vacuum/load during normal driving, so they should respond more precisely to fine changes in throttle position as you would encounter during daily driving. FWIW I always found spread bore carbs to be more responsive when driving around town than square bore carbs.
just here but since the TQ has much smaller primarys wouldn't that make the secondarys open faster? As mentioned before by me and others, a tuned carb is going to use the fuel/air it needs to push the car. What about a 6-pack? It runs off a small 2bbl most of the time. Anybody got andy real world numbers?
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Re: thermoquad VS. Holley 750 DP
[Re: Performance Only]
#1031727
07/14/11 09:53 AM
07/14/11 09:53 AM
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Joined: Feb 2005
Posts: 5,221 Branson, Mo.
joedust451
super gas
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super gas
Joined: Feb 2005
Posts: 5,221
Branson, Mo.
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Quote:
Quote:
The TQ or QJ will still win over a squarebore carb, smaller primary bores get better mileage if the AFR is the same on both carbs. & you can make a 750dp get right at the same mileage as a 3310.
if ther A/F ratio is the same for either carb, can you please explain why one will get better mileage over the other? same amount of air, same amount of fuel.
the one thing i could never get used to on a spread bore carb is how much further you need to push the gas pedal in normal driving to get the same acceleration as a square bore carb.
Its not really the same amount, i'm only talking on the primary side, Who drives around at WOT all the time, you have less air/fuel being drawn in on the smaller primary carb staying on the primaries, but yhou can still adjust the AFR to where you want it, now why wouldn't you think if the AFR was the same on both carbs, that the larger throttle bores would get the same mileage, The engine is able too pull in more air at the same throttle possition as the smaller primary carb,, lets say 1/4 on both carbs, so the larger throttle bodied carb lets the engine draw more air, more air needs more fuel, resalting in more consumption, its not a brain teaser.
But i do agree with you on how the larger primary carb feels better under moderate throttle (more responsive) then the smaller primary carb
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Re: thermoquad VS. Holley 750 DP
[Re: Mr.Yuck]
#1031729
07/14/11 11:13 AM
07/14/11 11:13 AM
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Joined: Nov 2004
Posts: 2,825 Sk. Canada
RemCharger
master
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master
Joined: Nov 2004
Posts: 2,825
Sk. Canada
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Quote:
Quote:
Quote:
Quote:
The TQ or QJ will still win over a squarebore carb, smaller primary bores get better mileage if the AFR is the same on both carbs. & you can make a 750dp get right at the same mileage as a 3310.
if ther A/F ratio is the same for either carb, can you please explain why one will get better mileage over the other? same amount of air, same amount of fuel.
the one thing i could never get used to on a spread bore carb is how much further you need to push the gas pedal in normal driving to get the same acceleration as a square bore carb.
The smaller venturis are supposed to be more responsive to small changes in vacuum/load during normal driving, so they should respond more precisely to fine changes in throttle position as you would encounter during daily driving. FWIW I always found spread bore carbs to be more responsive when driving around town than square bore carbs.
just here but since the TQ has much smaller primarys wouldn't that make the secondarys open faster? As mentioned before by me and others, a tuned carb is going to use the fuel/air it needs to push the car. What about a 6-pack? It runs off a small 2bbl most of the time. Anybody got andy real world numbers?
I thought the center carb on a 6 pak was like a 500. Same as a 67 and down carter 4 bbl
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Re: thermoquad VS. Holley 750 DP
[Re: Rug_Trucker]
#1031737
07/14/11 01:44 PM
07/14/11 01:44 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
"TQ's are great if you fix the throttle shaft slop in the rebuild. Also buy an air door tool off of Doc.
My 511 '67 Cuda got 14mpg combined with the 6pak."
I noticed on the 1st 6-pack build (mild 440 w/ 528 solid) I was getting pretty good milage. This build is much more agressive and on the last trip to the track (22 miles) I avg'd about 13-14. Not bad considering I got on it a few times. This is mainly backroads (45mph) stopping in 4 small towns.
Read down lower in my post. I got 7mpg. 3:23's .538-.5?? Crane solid cam.
I'm running .030 over 440 w/ a 588 solid roller, ported stage VI heads, 3800 stall and 3.91's. I think my good milage was do to a nice slow steady drive of 40-45mph. Not much stop/start and not much outboard action...
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Re: thermoquad VS. Holley 750 DP
[Re: Paul_Fancsali]
#1031741
07/16/11 04:16 AM
07/16/11 04:16 AM
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Joined: Jul 2005
Posts: 384 Australia
Mcode69
enthusiast
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enthusiast
Joined: Jul 2005
Posts: 384
Australia
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Quote:
The TQ takes a lot to tune and is absolutly no comparison to a DP Holley. I tried to run a TQ and succeeded but in the end the Holley won out hands down in Performance. When you are talking tenth's of a second I will now stick with Holley. PS in mileage try a Q jet easy to tune and reliable and with Chrysler linkage from 1985 up to 1988
If the holley won hands down in performance it means your TQ was WAY out of tune. I've had a 750DP and a TQ on the same engine and the difference was 11 mpg from the holley and 17 from the TQ around town. Never saw any track times but the TQ had the holley by the butt dyno. And apart from that [and here's a name from the past] Ed Hamburger insisted that a TQ will have 2 tenths over a similar sized double pumper all day. As someone stated previously holley tend to cover up deficiencies in their design by making it rich, they CANNOT meter fuel properly at part throttle apart from all their other problems.
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