Posted By: greenfire
thermo-quad - 04/27/09 06:07 PM
any one know what the cmf this themo-quad is? i pulled it off my 318, only #on it are 6-2141 and the #16 in larger size#
thermo-quad
Posted By: Anonymous
Re: thermo-quad - 04/27/09 06:22 PM
i think its 850 but not sure. what do you plan on doing with it?
Posted By: Anonymous
Re: thermo-quad - 04/27/09 06:25 PM
sorry i mistyped. should be between 750 and 800. i think 750 was the smallest thermoquad.
Posted By: stumpy
Re: thermo-quad - 04/27/09 06:30 PM
The # should be stamped into the corner of the base plate.
Posted By: Anonymous
Re: thermo-quad - 04/27/09 06:37 PM
are you looking to rebuild it or replace it. if replacing it a 600cfm eddy or holley would be a better choice. if you go with a 750 or bigger aftermarket they will bog out the engine a bit.
Posted By: Crizila
Re: thermo-quad - 04/27/09 06:39 PM
If the primary bores are 1 3/8", it is a 750 -800cfm. 1 1/2 primarys = 800 - 850 cfm.
Posted By: Rug_Trucker
Re: thermo-quad - 04/28/09 12:32 AM
Quote:
The # should be stamped into the corner of the base plate.
On the driver side rear.
If it is the correct carb, it will be an 800. A TQ will adjust it's CFM via engine demand and a properly adjusted air door.
Posted By: DEMONSIZZLER
Re: thermo-quad - 04/28/09 12:46 AM
Those are the top # id. It is a '75-early '78 top. As others said, check the driver rear corner of the base plate for the #'s to id the carb.
Also the #'s 2-310 or 2-315 stamped on the bottom side of the primary butterflies is an 800 cfm carb while the #'s 2-314 stamped on the primary butterfly bottom side is an 850 cfm carb, David.
Also the #'s 2-310 or 2-315 stamped on the bottom side of the primary butterflies is an 800 cfm carb while the #'s 2-314 stamped on the primary butterfly bottom side is an 850 cfm carb, David.
Posted By: greenfire
Re: thermo-quad - 04/28/09 04:17 PM
thanks guys, looks like it is a 800cmf tq a bit to much carb for a stock 318 imo. and the intake prolly had more leaks then a block of swiss cheese, what a mess lol. gonna put on edelbrock intake with a edelbrock 1405 600 cmf carb to day.
Posted By: Rug_Trucker
Re: thermo-quad - 04/28/09 11:29 PM
Quote:
A TQ will adjust it's CFM via engine demand and a properly adjusted air door.
Read that again. It really seems like you have no experience with carbs. You have the best carb in your hand for a mild engine.
Let Demonsizzler rebuild it. It would be cheaper and better than any after market NEW carb you could buy.
Did you get the model number off it??
Posted By: volaredon
Re: thermo-quad - 04/28/09 11:37 PM
Quote:Quote:
A TQ will adjust it's CFM via engine demand and a properly adjusted air door.
Read that again. It really seems like you have no experience with carbs. You have the best carb in your hand for a mild engine.
Let Demonsizzler rebuild it. It would be cheaper and better than any after market NEW carb you could buy.
Did you get the model number off it??
Ive had a few 318s with aftermarket carbs and none ran as well on there as a TQ. I'm gettin ready to send him (2) baseplates for a rebush job, now that he sent me his address today for shipping.
Posted By: HotRodDave
Re: thermo-quad - 04/28/09 11:38 PM
Quote:Quote:
A TQ will adjust it's CFM via engine demand and a properly adjusted air door.
Read that again. It really seems like you have no experience with carbs. You have the best carb in your hand for a mild engine.
Let Demonsizzler rebuild it. It would be cheaper and better than any after market NEW carb you could buy.
Did you get the model number off it??
An 800 thermoquad is in no way and no how too big for a bone stock 318. I have an 850 thermoquad on my super duper mpg 318 and it is very responsive and gets very good mpg and still pulls hard to 5000 RPM. If you need it fixed send it to demonsizzler or me or any number of thermo quad gurus or even do it your self, it is not very hard and they will run great and be way cheaper than an eddy carb.
PS I even had an 850 on a 273 once and it ran great. I have seen them on slant sixes also. There adjustable secondarie air door works VERY well.
Posted By: dOc …
Re: thermo-quad - 04/29/09 12:00 AM
The TQ can be made to "fit" most any cubic-inch engine. I helped a guy with a 273 using an 800 cfm one.
NO problem ... but you have to throttle-down the secondary side. And put appropriate jetting in it.
NO problem ... but you have to throttle-down the secondary side. And put appropriate jetting in it.
Posted By: CJK440
Re: thermo-quad - 04/29/09 12:25 AM
Keep in mind the rules change when dealing with a squarebore vs. a spreadbore carb.
A square bore had the same size primaries and secondaries which flow almost equal. So if you go too big with a squarebore the primary venturi's might be so big that the low speed "around the town" vacuum signal suffers.
With a spreadbore, especially one with a huge difference in size between the primary & secondaries like a TQ you can worry less about overcarburating since the primaries are so tiny and very responsive.
Think about this. Holley recomends that you undersize a carb vs too big so the car will have decent idle and midrange characteristics but the magazine builds always find more HP with an oversize Carb. A spread bore is the best of both worlds for a street/strip setup.
A square bore had the same size primaries and secondaries which flow almost equal. So if you go too big with a squarebore the primary venturi's might be so big that the low speed "around the town" vacuum signal suffers.
With a spreadbore, especially one with a huge difference in size between the primary & secondaries like a TQ you can worry less about overcarburating since the primaries are so tiny and very responsive.
Think about this. Holley recomends that you undersize a carb vs too big so the car will have decent idle and midrange characteristics but the magazine builds always find more HP with an oversize Carb. A spread bore is the best of both worlds for a street/strip setup.
Posted By: greenfire
Re: thermo-quad - 04/29/09 04:55 AM
Quote:experince with carbs? with holley yes, quadra-jets yes, and a few edelbrocks yes, with thermo-quads no and the quality black plastic base on this tq is in poor shape, cracked and full of pits not to mention that the previous owner frankensteined all the linkage. a friend donated a edey 600 cmf in good cond , so no charge for the carb, and i know it works. as well as a good match up for the edey intake i have.Quote:
A TQ will adjust it's CFM via engine demand and a properly adjusted air door.
Read that again. It really seems like you have no experience with carbs. You have the best carb in your hand for a mild engine.
Let Demonsizzler rebuild it. It would be cheaper and better than any after market NEW carb you could buy.
Did you get the model number off it??
Posted By: 375inStroke
Re: thermo-quad - 04/29/09 02:24 PM
Tons of info here: Thermoquad guide
Manuals, kits, and other stuff here: Carb Dr.
The adjustable air door works great on a Thermoquad. I used the same carb on a 318, then on a 440, and it got me 14.20@98MPH with a junk yard motor in a '69 Coronet. Same car with the 318 and that carb was much slower, but never any bog or mixture problems.
Manuals, kits, and other stuff here: Carb Dr.
The adjustable air door works great on a Thermoquad. I used the same carb on a 318, then on a 440, and it got me 14.20@98MPH with a junk yard motor in a '69 Coronet. Same car with the 318 and that carb was much slower, but never any bog or mixture problems.