q jet ,4 jet jets

Lyn Smith · 04-11-2015, 11:13 AM

Can you use quadrajet jets in a rochester 4 jet carb?Been a while since i worked on one. thanks

Dragsinger · 04-11-2015, 12:27 PM

Lyn,

I do not know the answer about jet size.

What I do have is one mid 60's Rochester 4 jet. If there is a desirable style I will check what I have. If you can use it pay the shipping.

Tom Meyer · 04-11-2015, 02:33 PM

Lynn the jets work but if you look at them the 4 jet is flat in the center the q jet is tapered or other way around, so they flow different. If you change from one to the other you may not be changing anything at all. I know that you can get them for a Holley but does anybody know where you can get jets flowed. Tom

Mark Yacavone · 04-11-2015, 11:21 PM

Lyn, The Q jets are tapered to accommodate the primary rods
Otherwise interchangeable...1/4 28 thread

Lyn Smith · 04-12-2015, 10:37 AM

Thanks for the info and help.

Dwight Southerland · 04-13-2015, 08:30 AM

Not all 4gc jets are flat across the inside. There were three different designs over the years - one was flat, one had a small 45 degree chamfer at the top and the third had a large 45 degree taper cut that extended half the distance of the jet body. All had different flow characteristics so it is imperative when tuning that the same style jets is used when changes are made. Qjet jets will fit, but you may have to experiment with sizes to get the correct fuel-air mix if you have references from one of the 4gc jet styles.

Tom Meyer · 04-13-2015, 09:47 PM

Thanks Dwight, I knew there was some different ones just not that many. What is going to happen when all this info will be gone? I hope someone is taking notes. Tom

Mark Yacavone · 04-13-2015, 11:14 PM

Quote:

Originally Posted by Tom Meyer

Thanks Dwight, I knew there was some different ones just not that many. What is going to happen when all this info will be gone? I hope someone is taking notes. Tom

That's why we're here,Tom.. Puttin' it all out there in the archives..

ZASKO · 04-13-2015, 11:43 PM

they are different, I wouldn't use but only the same

ZASKO · 04-13-2015, 11:46 PM

if you need a different jet, use what yu have a drill out if going larger.

04-11-2015, 11:13 AM	#1
Lyn Smith VIP Member Join Date: Dec 2001 Location: Pontiac,il. Posts: 1,205 Likes: 287 Liked 986 Times in 198 Posts	q jet ,4 jet jets Can you use quadrajet jets in a rochester 4 jet carb?Been a while since i worked on one. thanks

04-11-2015, 12:27 PM	#2
Dragsinger VIP Member Join Date: Jul 2008 Location: Liberty City [East Texas] Posts: 1,760 Likes: 5 Liked 99 Times in 60 Posts	Re: q jet ,4 jet jets Lyn, I do not know the answer about jet size. What I do have is one mid 60's Rochester 4 jet. If there is a desirable style I will check what I have. If you can use it pay the shipping. __________________ Larry Woodfin 471W

04-11-2015, 02:33 PM	#3
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 936 Likes: 78 Liked 354 Times in 120 Posts	Re: q jet ,4 jet jets Lynn the jets work but if you look at them the 4 jet is flat in the center the q jet is tapered or other way around, so they flow different. If you change from one to the other you may not be changing anything at all. I know that you can get them for a Holley but does anybody know where you can get jets flowed. Tom __________________ Tom Meyer 5240 SS Stock ??? Last edited by Tom Meyer; 04-12-2015 at 10:27 AM. Reason: added

04-11-2015, 11:21 PM	#4
Mark Yacavone Veteran Member Join Date: Mar 2002 Location: Miles From Nowhere Posts: 7,819 Likes: 2,910 Liked 5,127 Times in 1,955 Posts	Re: q jet ,4 jet jets Lyn, The Q jets are tapered to accommodate the primary rods Otherwise interchangeable...1/4 28 thread __________________ "We are lucky we don't get as much Government as we pay for." Will Rogers Last edited by Mark Yacavone; 04-12-2015 at 02:26 PM.

04-12-2015, 10:37 AM	#5
Lyn Smith VIP Member Join Date: Dec 2001 Location: Pontiac,il. Posts: 1,205 Likes: 287 Liked 986 Times in 198 Posts	Re: q jet ,4 jet jets Thanks for the info and help.

04-13-2015, 08:30 AM	#6
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 2,001 Likes: 64 Liked 780 Times in 194 Posts	Re: q jet ,4 jet jets Not all 4gc jets are flat across the inside. There were three different designs over the years - one was flat, one had a small 45 degree chamfer at the top and the third had a large 45 degree taper cut that extended half the distance of the jet body. All had different flow characteristics so it is imperative when tuning that the same style jets is used when changes are made. Qjet jets will fit, but you may have to experiment with sizes to get the correct fuel-air mix if you have references from one of the 4gc jet styles. __________________

04-13-2015, 09:47 PM	#7
Tom Meyer Senior Member Join Date: Aug 2003 Location: Pierce NE Posts: 936 Likes: 78 Liked 354 Times in 120 Posts	Re: q jet ,4 jet jets Thanks Dwight, I knew there was some different ones just not that many. What is going to happen when all this info will be gone? I hope someone is taking notes. Tom __________________ Tom Meyer 5240 SS Stock ???

04-13-2015, 11:43 PM	#9
ZASKO Junior Member Join Date: Nov 2006 Posts: 78 Likes: 0 Liked 0 Times in 0 Posts	Re: q jet ,4 jet jets they are different, I wouldn't use but only the same

04-13-2015, 11:46 PM	#10
ZASKO Junior Member Join Date: Nov 2006 Posts: 78 Likes: 0 Liked 0 Times in 0 Posts	Re: q jet ,4 jet jets if you need a different jet, use what yu have a drill out if going larger.