There's been a lot of posts relating to the secondary rods and hangars. I'm looking on suggestions for modifying the primaries. I'm swapping out my 305 for a mild 350 (mild cam, Perfmormer intake, headers). Its a 9:1 motor. I want to keep the Q-Jet because of emissions requirements (if it looks stock, it must be stock...). Any suggestions will be appreciated!

 

If you are SURE the primaries haven't been touched and are stock, then it's usually advisable to go up 2 jet sizes for best performance. Since you are also moving to a bigger motor I'd go up at least 4 jet sizes, resuing the original primary rods.

You should end up with a primary jet in the 72-76 range after the increase in jet size in most QJets. Primary rod size should be somewhere in the neighborhood of 42 to 46. No guarantees, just wanted you to know where "sanaity" is at when tuning one of these things.

I did one recently where I ended up going up 9(!!!!) jet sizes from 65 to 74 and it was still a smidge on the lean side. Inexpensive parts store "remanufactured" QJets are the WORST offenders when it comes to incorrect primary jetting- they'll run 'em so lean they squeak!



[This message has been edited by Damon (edited November 26, 2001).]

 

Thanks. I know I probably won't get it right the first time but the suggestion gives me a starting point to work from.

 

Are we talking about a computer controlled q-jet or mechanical?

 

Its a computer controlled Q-Jet (85). I'm sure the idle will be fine but I'm concerned about part throttle acceleration (up to and after secondaries kick in).

 

Correct me if I'm wrong, but the primary side of the E4ME is completely computer controlled and unmodifiable. It does its best to keep a 14.7:1 fuel ratio, though, regardless of the motor, so there's really no need to modify it. Works fine on my ZZ4.

 

That's why I asked. It works fine on my biggie-sized LG4 as well. Just a little more thirsty than it was before...

 

Sorry about that. I thought we wer talking about an old non-cc QJet.

DOn't touch the primary side of a CCQJet.

 

Once again, thanks. You just saved me a great big PITA!