Anyone running a Quadrajet 4v?

I have a Holley 390 great on road power, Motorcraft 2100 Great off road. Thinking about trying a Quadrajet now. I really like a 4v. Anyone running one. I've heard they are really good offroad.

 

It's in my sig but here is what I have. 1975 CJ5 258, Clifford intake, Headers dual exhaust,

 

I'm not expert on Q-jets, but I had thought they were all much too large for a 258? I thought the smallest was in the 750cfm range? But maybe the small primaries and vacuum secondaries would allow you to get away with it on a small displacement engine?

 

The secondaries only kick in if needed. My chevy 4.3 (262 i think) came stock with a 4v qjet..thats good enough for me. I have mine running pretty good, just needed some fine tuning, i have been told when they are dialed in, they are as close to FI as you can get in a carb.

 

Q jet is probably one of the best stock 4 v carbs for off road use.

Try and find a non computerized version off of a GM 4.3 V-6 or from the Buick 252 V-6. Both came stock with them and the cfm rating should be just about perfect for your 258.

 

I have had a Holley 460 (small primary(s) and much larger vacuum secondaries) with use of 1" spacer (great torque improvement) above an Offenhauser Intake (used my Dremel with fine grind wheel.. to clear passages of any rough facing noted) since delivery in 72'. My 258 is now bored .030 over and all I had to do was reduce the size of the primary and secondary jets to optimize (original delivery found idle and acceleration complaints... easily corrected with jet reduction after purchase) the acceleration, idle and tweek overall operation onroad and offroad... all has been fine and just recently replaced my original factory Holley (due to age, 190k) with the newer Holley 460... also, I am reusing the original jets in newer carb to allow a smooth transition.

Seriously, I have excellent operation... fantastic idle and have NO Problems in any offroad operation in over 28+ years of operation. I have no plan(s) to change any fuel hardware in the future!

Recommendation: Use the best inline fuel filter possible! Thinking seriously of an electric fuel pump as offroad backup for the mechanical with tubing and a "Y-valve" for easy switchover. Presently have my underseat tank as well as the rear fuel tank... using an electric valve for switch over with individual fuel level senders with one gauge... using a three way switch to view either tank's level easily. Having two tanks does come in handy with trips.

Gunner

 

Cool, Thanks. Looks like time to hit the junk yards. WHen did the 4.3 go computerized?

 

Some electric pumps are a designed so that fuel will flow through even if they are not running (sorry I dont remember which model). If you used that style you could just plumb it in and run it when needed.