Re: Help wtih carb choice, please...LA 360 rebuild
[Re: Supercuda]
#1585045
02/28/14 11:31 PM
02/28/14 11:31 PM
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Anonymous
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Anonymous
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QuickFuel 600 vacuum with electric choke $319 and one of the best OOB carbs on the market They are the best for the least out there--I install several a week and the 750 is the same $$ Killer street carbs repeat Killer for the money I would not install an Edelbrock if it was free Holleys way too much $$
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Re: Help wtih carb choice, please...LA 360 rebuild
[Re: Charger_440]
#1585046
03/01/14 01:59 PM
03/01/14 01:59 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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Guys guys guys...dyno testing tells all.
Go back to Steve Dulcich's Junkyard Jewel 400hp 318 article, the one where he ported the 302 heads to within an inch of their lives and did some dyno runs. That ultra heavy mid-70s 360 EGR manifold was only something like 25hp down on the Perf RPM at the top end of the horsepower charts. That intake is really good, just don't drop it on your foot!
Take a long look at it. It is a true highrise design, the ports are 360-sized and have decent curves. It was probably developed with a real eye towards fuel distribution.
It is a spreadbore intake, made to use a Thermoquad. The Street Demon will bolt right on, the SD is made to fit on either squarebore or spreadbore intakes.
About CFM: The Street Demon, the Thermoquad, the AVS/Thunder Series carbs, and Quadrajets all have adjustable air doors which will only let the carburetor be as big as the engine "wants" it to be. You could put a Thermoquad or any of those other carbs on a Slant Six and have them work properly. My Mercedes 173 cubic inch six came stock with a German copy of a Quadrajet that probably flows 700cfm wide open. Holley vacuum secondary carbs also tailor the carb size to engine demands.
R.
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Re: Help wtih carb choice, please...LA 360 rebuild
[Re: gdonovan]
#1585049
03/01/14 11:46 PM
03/01/14 11:46 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
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Quote:
Quote:
About CFM: The Street Demon, the Thermoquad, the AVS/Thunder Series carbs, and Quadrajets all have adjustable air doors which will only let the carburetor be as big as the engine "wants" it to be.
Not true on the AVS, the air door just replaces the counter weight system.
Not exactly. The counter AFB's weighted air door is in the carb, under the top plate. The AVS's adjustable air door is above the top plate and is adjusted in the same manor as the TQ. It will use two screw drivers to do. The AFB air door is adjustable via adding or deleTing the amount of weight of the counter weight. Not really adjustable IMO.
To the thread starter;
The TQ comes in two sizes commonly rated as a 800 & a 850. The small primary side of the carbs offer excellent drivability and throttle response. They have multiple ring boosters. Excellent amotimzation of the fuel.
The secondary sides are equal in size on both carbs @ 2-1/4 inch each side. The adjustable air door allows the door to open later on a more mello engine or sooner for a heavy breather. Engine size barley matters with this carb.
The only thing I can suggest is use the small primary (1.38) on 318/273 engines or a near stock 340/360. Use the larger primary (1.50) on 340 and up engines. Even better if the engine has some guts. (AKA Balls)
Tuning parts are really hard to find. I wouldn't use the carb if you do not all ready have spare parts to tune with.
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Re: Help with carb choice, please...LA 360 rebuild
[Re: gdonovan]
#1585054
03/03/14 12:27 AM
03/03/14 12:27 AM
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Joined: Jan 2003
Posts: 715 Tulsa, Oklahoma
Charger_440
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Tulsa, Oklahoma
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ok, good info guys. let's refocus this thread once more. say I use the stock spread bore intake I have...let's talk about carb options that will bolt onto that manifilold. the tq is out just due to the cfm being too much for my build.
we have the street demon and the quickfuel mentioned above. what are some other good carbs in the pricerange between 650 and 750 cfm?
I prefer vacuum secondaries
Last edited by charger_440; 03/03/14 12:31 AM.
In a conversation with a Wyoming State Patrolman... "A 318 ??!!! But I clocked you at 142 mph!!!"
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Re: Help with carb choice, please...LA 360 rebuild
[Re: Charger_440]
#1585055
03/03/14 02:29 PM
03/03/14 02:29 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
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Quote:
ok, good info guys. let's refocus this thread once more. say I use the stock spread bore intake I have...let's talk about carb options that will bolt onto that manifilold. the tq is out just due to the cfm being too much for my build.
Ummmm, sorry, but that is completely inaccurate since TQ's came on 318's in the lTe 70's with power ratings of 180 HP. (Maybe less even )
If you can find a good working unit, just use the small primary TQ. That is IF you want to use a TQ. Take the CFM rating out of your head because it is misleading you. The small primary large secondary design of a spreadbore carb make them flexable enough to use on your mello build, which is a little bit more than stock right? The worst you'll have to do is change a rod.
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Re: Help with carb choice, please...LA 360 rebuild
[Re: Rob C]
#1585056
03/03/14 03:07 PM
03/03/14 03:07 PM
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Joined: Jan 2003
Posts: 12,801 Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
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The TQ is out because the OP says he prefers a vacuum secondary style carb.
Besides, he also said that he already had a Street Demon. If he doesn't want to run that one, he sure wouldn't want an old TQ.
Master, again and still
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Re: Help with carb choice, please...LA 360 rebuild
[Re: Rob C]
#1585057
03/03/14 03:29 PM
03/03/14 03:29 PM
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Joined: Jan 2003
Posts: 16,376
dogdays
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I Live Here
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First things first: If you are a relative newbie, buy a brand new carburetor. It's all right for the old hands to say Thermoquad, but to a newbie the TQ is chancy at best. Part and tuning supplies can be problematic, and the knowledge to tune one is rare. That being said, if you had a TQ guru living next door it would be an excellent choice.
Your first choice should be a Street Demon, 625 cfm. It will bolt onto your stock spreadbore intake. Get the one with the plastic center section. Dunnuck says it is almost perfect out of the box, and I believe him.
You are working under a number of misconceptions.
1. Any carburetor with an adjustable air door or vacuum secondaries can be made to work with your 360. Read my previous post again. Spreadbores especially work for any kind of engine because the small primaries do a lot of the work. An 800 Thermoquad is not too big for your engine. Period. Or a 750cfm Quadrajet, etc.
2. Vacuum secondaries have the same function as a tunable air door so there is no advantage to going that way, except that all vacuum secondary carbs are Holleys, and Holley tuning knowledge and parts are widespread.
3. Quick Fuel Technologies, Barry Grant and Holley are all Holley designed and built carburetors The only new carb you are likely to see that ISN'T built by Holley is the Edelbrock.
A Thermoquad hasn't appeared new on a car or truck for decades. But give Holley (BG) credit for building the Street Demon, a brand new carb that keeps the best qualities of a TQ while being all new and bolting on either squarebore or spreadbore intakes without adapters. It also looks a lot like a carb that is supposed to be sitting on top of a 360.
R.
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Re: Help with carb choice, please...LA 360 rebuild
[Re: dogdays]
#1585058
03/03/14 04:20 PM
03/03/14 04:20 PM
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Joined: Jan 2003
Posts: 715 Tulsa, Oklahoma
Charger_440
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so, although it is an 800 cfm, it doesn't act like one? it can be choked down? if its true that they're as adjustable as they need to be, then I wouldn't mind a tq. does it really just throw as much fuel as the engine asks for? that would negate the above arguments over this carb or thay being too large or too small...I am not a newbie but also dont have any experience tuning a tq. youre sure that with proper tuning the tq wouldnt drown my 360?
what makes them hard to tune just a lot of adjustments, or what? how do I tune one? lay it on me. lol
at 625 isnt the demon a little small?
Last edited by charger_440; 03/03/14 06:43 PM.
In a conversation with a Wyoming State Patrolman... "A 318 ??!!! But I clocked you at 142 mph!!!"
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Re: Help with carb choice, please...LA 360 rebuild
[Re: DaveRS23]
#1585060
03/03/14 10:20 PM
03/03/14 10:20 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
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Quote:
The TQ is out because the OP says he prefers a vacuum secondary style carb.
While the TQ isn't exactly a vacuum operated secondary carb, it should be considered one. While the butterfly operation of the carb is strictly mechanical in nature, the air door above it is velocity sensitive. As the engine demands more air, and with the secondary butterflies opened, the air starts to move past the top air door at an increasing rate. As the velocity of the air becomes great enough to over come the air doors springs tension, it opens.
There is also a vacuum choke pull off tube/passage that will cancel this operation.
Quote:
Besides, he also said that he already had a Street Demon. If he doesn't want to run that one, he sure wouldn't want an old TQ.
Besides? Is not needed here because I was mentioning the misconception into a correction and understanding as to why and what I wrote. Please re-read thoroughly and not assume of me, thanks. I'm not trying to convince him to use one.
Also, I agree that a new guy would probably be overcome with a TQ. Even more so, into frustration if it is not in good shape. Vacuum and or fuel leaks at the shafts or where the gaskets are can be a huge pain to deal with. Actually, there is a lot to deal with on this carb. IMO, it is not really for the meek or untalented.
However, IMO, once you learn the carb, there a blast. I mostly find them inexpensive to obtain and rebuild. To say there a great bang for the buck is a understatement considering dollar spent vs. CFM obtained. There is a learning curve with these carbs. How much of a curve is up to the person themselves.
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Re: Help with carb choice, please...LA 360 rebuild
[Re: dogdays]
#1585061
03/03/14 10:23 PM
03/03/14 10:23 PM
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Joined: Mar 2005
Posts: 792 Earth
Rob C
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super stock
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First things first: If you are a relative newbie, buy a brand new carburetor. It's all right for the old hands to say Thermoquad, but to a newbie the TQ is chancy at best. Part and tuning supplies can be problematic, and the knowledge to tune one is rare. That being said, if you had a TQ guru living next door it would be an excellent choice.
Charger440; That's the home run in the bold! You'll be way a head of the curve. And yes, the TQ can be "Choked down" though it should be said, tuned down. The engine will demand only so much air and the TQ will give what it wants, and that's it. Without getting into a long drawn out post, you have the idea.
There is a book on everything you wanted to know about Carter carbs (And Edelbrocks too) plus some info that only rates as interesting to know. But it is a good read. Pick on up and enjoy it. It's good to have on the shelf.
Last edited by Rob C; 03/03/14 10:29 PM.
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Re: Help with carb choice, please...LA 360 rebuild
[Re: Rob C]
#1585062
03/03/14 10:41 PM
03/03/14 10:41 PM
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Joined: Jan 2003
Posts: 12,801 Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 12,801
Benton, IL.
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Quote:
Quote:
The TQ is out because the OP says he prefers a vacuum secondary style carb.
While the TQ isn't exactly a vacuum operated secondary carb, it should be considered one. While the butterfly operation of the carb is strictly mechanical in nature, the air door above it is velocity sensitive. As the engine demands more air, and with the secondary butterflies opened, the air starts to move past the top air door at an increasing rate. As the velocity of the air becomes great enough to over come the air doors springs tension, it opens.
There is also a vacuum choke pull off tube/passage that will cancel this operation.
Quote:
Besides, he also said that he already had a Street Demon. If he doesn't want to run that one, he sure wouldn't want an old TQ.
Besides? Is not needed here because I was mentioning the misconception into a correction and understanding as to why and what I wrote. Please re-read thoroughly and not assume of me, thanks. I'm not trying to convince him to use one.
Also, I agree that a new guy would probably be overcome with a TQ. Even more so, into frustration if it is not in good shape. Vacuum and or fuel leaks at the shafts or where the gaskets are can be a huge pain to deal with. Actually, there is a lot to deal with on this carb. IMO, it is not really for the meek or untalented.
However, IMO, once you learn the carb, there a blast. I mostly find them inexpensive to obtain and rebuild. To say there a great bang for the buck is a understatement considering dollar spent vs. CFM obtained. There is a learning curve with these carbs. How much of a curve is up to the person themselves.
Rob, I don't necessarily disagree with you. I was merely addressing the OPs concerns.
Your job is to convince the OP that your points are valid to him. He has been told on here by several posters that the Street Demon is his best chance for OOTB success. He said that is not the way he wanted to go. You want to convince him otherwise.
Good luck.
The TQs are okay. But they are the last carb that I would recommend to anyone that is asking for advice here.
I meant no disrespect. I was only trying to clarify the OP's position.
Master, again and still
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Re: Help with carb choice, please...LA 360 rebuild
[Re: DaveRS23]
#1585063
03/03/14 11:38 PM
03/03/14 11:38 PM
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Joined: Jan 2003
Posts: 715 Tulsa, Oklahoma
Charger_440
OP
super stock
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OP
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Joined: Jan 2003
Posts: 715
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I didnt ever say I had a street demon. I dont have a carb at all yet, so I hadnt said I didnt want the demon. im taling all info in and learning from it. I am, from what I am seeing here, leaning strongly towards the street demon 750.
I appreciate everything that all of you have contributed and are contribiting to the thread.
In a conversation with a Wyoming State Patrolman... "A 318 ??!!! But I clocked you at 142 mph!!!"
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