Thermoquad vs Quadrajet

GTX JOHN · 12-15-2009, 04:15 PM

My Stock Dodge Truck (N/SA) can run either a small (1 and 3/8 ) Thermoquad or a quadrajet. I never used a Quadrajet since I race mopars. Is it any faster, I know It couldn't be much harder to figure out? Are the Edelbrock carbs preferable?

Thanks John Irving

George Mirza · 12-15-2009, 08:06 PM

It would be interesting to see which one is faster. At least you can buy a new quadrajet, not a 30 year old TQ that might be good.
I bet a few SS racers have been there already and can tell you which is better. The mid 80's 318 combo is pretty good in SS and I think you can run either carb on it depending on year claimed.

GTX JOHN · 12-15-2009, 08:40 PM

The 318 engine in superstock is rated 4 more HP with a Quadrajet than
Thermoquad I didn't know you could buy a quadrajet new. I know jet sell a race carb but I didn't know if was a new unit or rebuilt. Does anybody know if the are usable(Jet Race Model) out of box. Who can I pay to rework one on West Coast that is compentent? Thanks

GTX JOHN · 12-15-2009, 08:48 PM

The 318 SS is four more HP with Quad but it still seems more popular. Same HP on 360 Truck. Didn't know you could buy either one new anymore. Jet sell a Quad the state is Stock/SS ready but I thought it was rebuilt not new. Does anybody know if they work? Any reccomendations on who to have build me one on West Coast? Thanks

SORRY Didn't mean to post twice in a row

Todd Boyer · 12-15-2009, 10:45 PM

I haven't heard his name in quite some time, but isn't Val Hedworth a good Q-Jet man? Not sure on this John as I'm a Mopar man myself. I also believe Ken Etter runs a Q-Jet on his 318 SS Shadow.

Todd Boyer · 12-15-2009, 10:47 PM

I also believe Greg Gay runs, or at least can run, both carbs on his 318 SS Mirada, but not sure who does his carbs.

Philip Saran · 12-15-2009, 11:10 PM

GTX John,

Give Bob Mazzolini a call at his shop. I believe he ran the QJ on both of his
old SSGT cars that are now owned by Wayne Taylor and Bill Riddle, also talk
with Ken Etter about this.

Dragsinger · 12-16-2009, 06:01 AM

Also consider talking with Danny Ashley. He post here and is an accomplished Q-jet builder.

njk53 · 12-16-2009, 10:48 AM

Speak to Dean Oliver (870) 830-5470. Excellent and knowledgable Q-Jet builder and an easy person to talk to.

Danny Ashley · 12-16-2009, 12:08 PM

Larry,
Thanks for the plug. Your new car looks great!

John,
I'v never heard of anyone comparing the Q-Jet with a Thermoquad so here's my opinion. Since both are rated at 800 cfm and if you had both properly jetted, it should be a wash. The engine doesn't know type just flow. You would have to compare a known good Q-Jet with a known good Thermoquad to know for sure. I assume that in the Thermoquad world as in the Q-Jet's, there is sometimes a big difference between cores. You could do up 5 of the same number and one would probably be faster. Dynos won't tell you either. The real test is the time slip. Period. If you choose to go with an Edelbrock, there are 4 numbers you can use; #1903, 1904, 1910, and 1905. The 1910 claimes to be an 850 but the primaries measure 1.218 which is what a 800 is. The 1905 is a direct replacement fot the Thermoquad on 1985 and earlier engines so it will have the correct linkage for Mopar engines. The Edelbrock are no longer manufactured and only occasionally will you find a new one from a parts supplier. E-Bay is a good source for used ones and sometimes there are new ones on there also. 800 cfm Quadrajets were used on a wide variety of GM engines from 301 to 455 in Buick, Olds, Pontiac, Cadilliac, and Chevy so if you know what to look for they can be found on E-Bay also. I stock new and used 800's. Don't be afraid to have someone outside California blueprint a Q-Jet for you as ther are a lot of good builders out there. Some of my Calif. customers include Grossi, DeFrank, Glassbrenner, Tim Smith, Bob Aceves, Bob Mulrey,and Ed Drucker . I'm not suppose to advertise on here so if you need my number maybe someone will post it or you can PM me. Danny

12-15-2009, 08:06 PM	#2
George Mirza Senior Member Join Date: Jan 2002 Location: North Attleborough Ma. Posts: 522 Likes: 0 Liked 0 Times in 0 Posts	Re: Thermoquad vs Quadrajet It would be interesting to see which one is faster. At least you can buy a new quadrajet, not a 30 year old TQ that might be good. I bet a few SS racers have been there already and can tell you which is better. The mid 80's 318 combo is pretty good in SS and I think you can run either carb on it depending on year claimed.

12-15-2009, 08:40 PM	#3
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,530 Likes: 2,226 Liked 1,809 Times in 572 Posts	Re: Thermoquad vs Quadrajet The 318 engine in superstock is rated 4 more HP with a Quadrajet than Thermoquad I didn't know you could buy a quadrajet new. I know jet sell a race carb but I didn't know if was a new unit or rebuilt. Does anybody know if the are usable(Jet Race Model) out of box. Who can I pay to rework one on West Coast that is compentent? Thanks

12-15-2009, 08:48 PM	#4
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,530 Likes: 2,226 Liked 1,809 Times in 572 Posts	Re: Thermoquad vs Quadrajet The 318 SS is four more HP with Quad but it still seems more popular. Same HP on 360 Truck. Didn't know you could buy either one new anymore. Jet sell a Quad the state is Stock/SS ready but I thought it was rebuilt not new. Does anybody know if they work? Any reccomendations on who to have build me one on West Coast? Thanks SORRY Didn't mean to post twice in a row Last edited by GTX JOHN; 12-15-2009 at 10:30 PM.

12-15-2009, 10:45 PM	#5
Todd Boyer Senior Member Join Date: Feb 2004 Location: Saint John NB Canada Posts: 560 Likes: 27 Liked 6 Times in 5 Posts	Re: Thermoquad vs Quadrajet I haven't heard his name in quite some time, but isn't Val Hedworth a good Q-Jet man? Not sure on this John as I'm a Mopar man myself. I also believe Ken Etter runs a Q-Jet on his 318 SS Shadow.

12-15-2009, 10:47 PM	#6
Todd Boyer Senior Member Join Date: Feb 2004 Location: Saint John NB Canada Posts: 560 Likes: 27 Liked 6 Times in 5 Posts	Re: Thermoquad vs Quadrajet I also believe Greg Gay runs, or at least can run, both carbs on his 318 SS Mirada, but not sure who does his carbs.

12-15-2009, 04:15 PM	#1
GTX JOHN VIP Member Join Date: Jun 2009 Location: Boulder City, Nevada 89005 Posts: 2,530 Likes: 2,226 Liked 1,809 Times in 572 Posts	Thermoquad vs Quadrajet My Stock Dodge Truck (N/SA) can run either a small (1 and 3/8 ) Thermoquad or a quadrajet. I never used a Quadrajet since I race mopars. Is it any faster, I know It couldn't be much harder to figure out? Are the Edelbrock carbs preferable? Thanks John Irving

12-15-2009, 11:10 PM	#7
Philip Saran Senior Member Join Date: Oct 2006 Location: Parker, CO. Posts: 721 Likes: 158 Liked 14 Times in 11 Posts	Re: Thermoquad vs Quadrajet GTX John, Give Bob Mazzolini a call at his shop. I believe he ran the QJ on both of his old SSGT cars that are now owned by Wayne Taylor and Bill Riddle, also talk with Ken Etter about this. __________________ Phil Saran Parker, Colorado

12-16-2009, 06:01 AM	#8
Dragsinger VIP Member Join Date: Jul 2008 Location: Liberty City [East Texas] Posts: 1,759 Likes: 5 Liked 99 Times in 60 Posts	Re: Thermoquad vs Quadrajet Also consider talking with Danny Ashley. He post here and is an accomplished Q-jet builder. __________________ Larry Woodfin 471W

12-16-2009, 10:48 AM	#9
njk53 Senior Member Join Date: Jul 2007 Location: East China, MI Posts: 504 Likes: 0 Liked 0 Times in 0 Posts	Re: Thermoquad vs Quadrajet Speak to Dean Oliver (870) 830-5470. Excellent and knowledgable Q-Jet builder and an easy person to talk to. __________________ Nelson Kowal Stock 345

12-16-2009, 12:08 PM	#10
Danny Ashley Member Join Date: Nov 2001 Location: Marion,In. Posts: 257 Likes: 41 Liked 91 Times in 23 Posts	Re: Thermoquad vs Quadrajet Larry, Thanks for the plug. Your new car looks great! John, I'v never heard of anyone comparing the Q-Jet with a Thermoquad so here's my opinion. Since both are rated at 800 cfm and if you had both properly jetted, it should be a wash. The engine doesn't know type just flow. You would have to compare a known good Q-Jet with a known good Thermoquad to know for sure. I assume that in the Thermoquad world as in the Q-Jet's, there is sometimes a big difference between cores. You could do up 5 of the same number and one would probably be faster. Dynos won't tell you either. The real test is the time slip. Period. If you choose to go with an Edelbrock, there are 4 numbers you can use; #1903, 1904, 1910, and 1905. The 1910 claimes to be an 850 but the primaries measure 1.218 which is what a 800 is. The 1905 is a direct replacement fot the Thermoquad on 1985 and earlier engines so it will have the correct linkage for Mopar engines. The Edelbrock are no longer manufactured and only occasionally will you find a new one from a parts supplier. E-Bay is a good source for used ones and sometimes there are new ones on there also. 800 cfm Quadrajets were used on a wide variety of GM engines from 301 to 455 in Buick, Olds, Pontiac, Cadilliac, and Chevy so if you know what to look for they can be found on E-Bay also. I stock new and used 800's. Don't be afraid to have someone outside California blueprint a Q-Jet for you as ther are a lot of good builders out there. Some of my Calif. customers include Grossi, DeFrank, Glassbrenner, Tim Smith, Bob Aceves, Bob Mulrey,and Ed Drucker . I'm not suppose to advertise on here so if you need my number maybe someone will post it or you can PM me. Danny