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I have noticed a lack of an exhaust crossover to heat the carb on Vortec heads. Has anybody noticed any problems with running Vortecs on the street with a carb, particularly low temp driveability. I will stick with the stock 180 degree thermostat for now, but I may try up to 210 if I have any problems.
I've got Vortecs, drilled for steam holes, on my 406. It runs at about 180-190. The only time I can remember it going over 200 was in recent hot weather, in traffic.
I'm not worried about high temps, I'm worried about the temperature of the manifold not being high enough properly vaporize the fuel. If it means anything, the carburator is a QJet that I will be converting to electric choke.
if the carb and manifold are up to par, heating the fuel wont matter... as long as its vaporizing, the cooler you can keep it, the more performance you'll be pulling out of it
ive got vortecs on my motor and i have only had 1 problem. my problem is the fuel used to get to hot and pre deteonate. i fixed it with a spacer between the intake and the carb. do your self a favor, off the Q-JUNK carb and get a HOLLEY or a EDELBROCK!(JMO)
That's good to know, you had exactly the opposite of the problem I was worried about. I am sticking with the QJet for 2 reasons, I need the motor to look as stock as possible so I can sneak it past a less observant smog inspector and the QJet gets better milage. Afterall, this is a milage priority build.
the Q-JUNK gets better milage, if you keep your foot off the the floor board! those secondary toilets are HUGE! also, edelbrock and holley both make 50 state street legal carbs, they arent cheap, but they are availible. its a good way to get away from the nightmares and headaches that Q-Jets can cause. again, good luck
For our 85 chevy K10, we used vortec heads and a Q-Jet from Jet Performance. Their carb arrived in perfect adjustment....had to only adjust the idle screw after install. The thing had all the typical Q-Jet tricks installed like epoxied plugs, bushed shafts, etc. IT was cheaper than a new carb too!
mike in tucson
The only nightmare about a QJet is getting all of the cams and linkages assembled correctly after doing a rebuild. I absolutely love the QJet I had on my old engine and that is why it is going to be transplanted onto the new one. The throttle response isn't as crisp as a holley because of the transition to those huge primaries, but it makes all of the power of any other carb at WOT.
I'm running Vortec heads on the 350 in my roadster. I don't drive it very much in cold weather but it is fine after it warms up.
Vortec heads were used on FI motors. The puter corrects for temp so exhaust heat to the intake is not required.
I plug the riser holes in my manifolds and run the engines at -40 degrees with no real problem, takes a minute longer to warm up is all.
hi guy, if your having a problem with the q-jet going into the secondaries, then try ajusting the top secondaries on the side with an alen wrench (theres a spring in there) just turn the adjusting screw to tighten the flap up alittle, it will give you a better smoother responce under wot, you may have to do this acouple of times to get it right