highwaystar
Well-Known Member
for tunability, performance, and daily street driver. Who wins?
750 AVS or Thermoquad?
- Thread starter highwaystar
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stroked 340
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For tunability neither of those carbs...
dustoff440
Well-Known Member
As far as I know tq jets and rods are hard to come by, but a dialed in tq is VERY hard to beat. The small primaries provide very crisp throttle response. It is by far the best street carb I have run. If you follow the instructions provided by Edelbrock for his carbs you can tune them but be prepared to pull the lid off the carb quite a few times until you get it right.
In short, I like the TQ. But read on.........
Innncorrect to a large degree. And this is why;
Both carbs (Assumed OE units) are very tuneable. Both have 3 step rods for idle/driving down the road, part throttle/acceleration, and W.O.T. (Wide open throttle) But there OE carbs. There only so flexable.
OE Holleys are less tunable but very customizeable. So, while it's possible to make a better carb out of a Holley, it'll cost more since you have to purchase parts over the base purchase of the carb. Then of course, you can allways go out and spend 3 times the amount for a really nice holley with all sorts of trick things built into it.
Between the two carbs, the AVS and T-Q, you can do very well. Newer T-Q's have an edge if your not going to radical on the engine build. They came with Alttiutde (SP!) adjuster/compinsaters (More sp!) to enrichen or lean out the carb. So driving from the shore lines to up a few thousand feet, the carb stays in tune. It may not be the best, most accurate, but they worked preety good for there design and non-computered/metered help.
The cave eat to the TQ/AVS, is the lack of metering rods to tune them up real well. You'll have to search/hunt them down and probably purchase a used carb with the metering rods intact. I had to do this, and still do this for my TQ carb(s)
While you can use/adapt AFB rods, they are shorter and you will need the AFB rod covers to swap onto a AVS for there use. In doing so, you gain and loose tuneabilty. The gain is in selection of rods, the loss is there only 2 step rods.
These rods can also be bent (Shortened) for use in a TQ. You need to shorten them 3/4 of an inch.
While I like both carbs and I have NO issues with Holleys, the driveabilty / mileage/power output from any carb relies on the abilty to tune them well. I have had great sucess with Holleys and Carters. But the OE Carter carbs (again) are only so flexable and custmizeable. Once you start running big cams, there hard to tune in and get working really nice. At this point, you might want to look at a nince, upgraded Holley, far removed from a basic Holley to bolt on and use.
Ignorant statement.
Innncorrect to a large degree. And this is why;
Both carbs (Assumed OE units) are very tuneable. Both have 3 step rods for idle/driving down the road, part throttle/acceleration, and W.O.T. (Wide open throttle) But there OE carbs. There only so flexable.
OE Holleys are less tunable but very customizeable. So, while it's possible to make a better carb out of a Holley, it'll cost more since you have to purchase parts over the base purchase of the carb. Then of course, you can allways go out and spend 3 times the amount for a really nice holley with all sorts of trick things built into it.
Between the two carbs, the AVS and T-Q, you can do very well. Newer T-Q's have an edge if your not going to radical on the engine build. They came with Alttiutde (SP!) adjuster/compinsaters (More sp!) to enrichen or lean out the carb. So driving from the shore lines to up a few thousand feet, the carb stays in tune. It may not be the best, most accurate, but they worked preety good for there design and non-computered/metered help.
The cave eat to the TQ/AVS, is the lack of metering rods to tune them up real well. You'll have to search/hunt them down and probably purchase a used carb with the metering rods intact. I had to do this, and still do this for my TQ carb(s)
While you can use/adapt AFB rods, they are shorter and you will need the AFB rod covers to swap onto a AVS for there use. In doing so, you gain and loose tuneabilty. The gain is in selection of rods, the loss is there only 2 step rods.
These rods can also be bent (Shortened) for use in a TQ. You need to shorten them 3/4 of an inch.
While I like both carbs and I have NO issues with Holleys, the driveabilty / mileage/power output from any carb relies on the abilty to tune them well. I have had great sucess with Holleys and Carters. But the OE Carter carbs (again) are only so flexable and custmizeable. Once you start running big cams, there hard to tune in and get working really nice. At this point, you might want to look at a nince, upgraded Holley, far removed from a basic Holley to bolt on and use.
dustoff440
Well-Known Member
I wish I'd thought about using the shortened rods in the TQ Just months ago I sold a brand new AFB Strip Kit!! Good info Rumble.
highwaystar
Well-Known Member
Hi Rumble,
I guess I should of been clear on the intent of what type of motor. More of a street driver, less than 500 lift cam. 3.23 to 3.91 gear 9.1 to 10.5 to1 compression. I have also have had alot of TQ's and have liked them, but i remember an AVS I had on a factory 68 Coronet 500 with a 383 HP auto and that S.O.B ran like a Muther. I beat up on some 440 Coronet's and a GTX with that car. That was 20 years ago, but I loved that carb, hadn't really had any since and am thinking about getting one again.
I guess I should of been clear on the intent of what type of motor. More of a street driver, less than 500 lift cam. 3.23 to 3.91 gear 9.1 to 10.5 to1 compression. I have also have had alot of TQ's and have liked them, but i remember an AVS I had on a factory 68 Coronet 500 with a 383 HP auto and that S.O.B ran like a Muther. I beat up on some 440 Coronet's and a GTX with that car. That was 20 years ago, but I loved that carb, hadn't really had any since and am thinking about getting one again.
Lift has little to do with it all, it's more in the duration of the cam. Your parameters are wide. If you decide on a AVS, I'd look at a new Thunder series carb.
dustoff440
Well-Known Member
Agreed, buy a strip kit what are they 45 bucks now.
I can't preach the MP engine manual enough. How to tune the Thermoquad is all there, including how to make custom "club foot" metering rods. It's the best book you'll ever but regarding Mopar.
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