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

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.

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

Re: q jet ,4 jet jets
 

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

Re: q jet ,4 jet jets
 

Thanks for the info and help.

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.

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

Re: q jet ,4 jet jets
 

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

Re: q jet ,4 jet jets
 

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

Re: q jet ,4 jet jets
 

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

Re: q jet ,4 jet jets
 

Z, I'm sure you've done it or you wouldn't have mentioned it..as have I, in a pinch on some weird application.
But, seeing jet holes are broached, not drilled, one could get into some strange flow characteristics there, I would think.

Re: q jet ,4 jet jets
 

What Mark said!

Re: q jet ,4 jet jets
 

Most of the 4gc carbs from about 1958 up that I have seen used the chamfered entry jets. Some exceptions I remember were from marine applications. 'Back in the day' we collected jets from old carburetors and could resize them a few thous and it seemed to work okay. Cal Custom and EelCo sold sets of Rochester jets, but they were all flat entry and the holes were drilled and they did not work. I chased a .3 et loss for a couple of weeks once that was due to using those jets. I think I threw them all away or gave them to Kenny Faulk or somethin'.


Talk to Deano.