scrappy76

I swapped in my 76 vette a couple years ago a stock 454 that came from a motorhome. All is well. Right now I am running sidepipes, and as of Saturday I removed the stock intake and installed a edlebrock performer 2101 intake manifold. My question is, I am thinking of replacing the stock Qjet that was on it with a clean Qjet that was on a 76 corvette 350 L82
motor. Do you think the 350 Qjet is enough or should I just stick with the one that was originally on the 454 ?

mikem350

If "all is well", why swap? What year is the Qjet? Give it a cleaning and rebuild. If you want more performance you can have it re calibrated by a specialist on this forum.

Kris Tunetso

I admit to knowing next to nothing about carburetors, but I would think you'd want to stick with the 454 carb as it should be tuned to the needs of the engine. The 350 carb would probably have to be re-tuned.

7T1vette

The Q-Jet is a "demand" carb...meaning that the carb only opens the secondaries as far as it needs to supply whatever engine it is on. That's why a Q-Jet was applied to everything from the Pontiac overhead cam 6-cylinder engine to all the GM big blocks (454, 455, etc.)

Basically, the primary rods & jets and the secondary rods (as a minimum) would need to be changed when moving the carb between a 350 ci engine to a 454 ci engine. For specific recommendations on changes, I'd suggest that you contact Lars Grimsrud at V8FastCars@msn.com and request his advice on the changes needed.

But, there will be no problem with a Q-Jet from a 350 engine being used on a 454, if it is adjusted appropriately. All Q-Jets had [at least] 750 cfm flow capability. (some of them were 800 cfm units)

scrappy76

One of the reasons I was asking is the 454 carb is pretty filthy and I had talked with Lars about him rebuilding it and he said he doesnt mess with carbs in that year range. So I figured once I changed the manifold I would install the 350 Qjet the had been rebuilt by someone a few years back and only had a few thousand miles on it since the rebuild, maybe it work work better than the original 454 Qjet. I actually installed the 350 Qjet on the motor yesterday and fired it up. Seemed to work good at idle and revving it up a few times. I will fine tune it and set the timing here in a few days and take it for a spin.
Question : The old carb had an electric choke. The 76 Qjet looks like it has a vacuum choke ? Where or how does it hook up ? It has a rubber tube coming off it, where does it go ?

scrappy76

Well I went searching and saw that the vacuum line off the choke goes to a plate on the manifold. Really do not know what parts I would need. Can I convert the vaccum choke to an electric choke by using the parts off the old electric choke qjet ?

scrappy76

Lol I am really babbling here. Anhoo I keep calling it vacuum choke when its a hot air choke. I found some info on converting it over to electric. Anyone here done this ?

donaldb1

Maybe you can post the number from each carburetor. Neither carburetor may be original to either engine. The metering rods and jets may have already been changed.

Kris Tunetso

That's what I meant by having to tune the carb to the engine. You said it better.

7T1vette

Yes, you can convert to an electric choke if you want. A 'hot air' choke would be a step backwards, IMO. Most mid-70's and later GM carbs had a divorced-choke setup which would nearly close the choke plate on the carb when the accel pedal was tapped before starting the engine. Then, once the engine started, a vacuum operated 'choke pull-off' servo would release that choke plate to upright position. In essence, the choke would only be on while the engine was starting and then, once running and making vacuum, the choke would drop out.

An electric choke system simplifies that same process, so either method will work. The 'hot air' choke system will work, too; but it can go out of adjustment or get clogged up and not function well.