305 Qjet swap to Holley 3310

I have an 86 c10 with a 305 and QJET. I have played with the carb to the best of my ability, to no avail. The truck sputters and I have to feather the pedal to get it to move. I have a Holley 3310 that is freshly rebuilt and would love to swap that in the QJET'S place but need to know what type of steps I need to take to make the swap as painless as possible. I am very apprehensive that the 3310 is "too much" carb for the 305.

I know very little about the electrical running to the QJET. Any help would be greatly appreciated, I'm a student who loves wrenching on cars and I am just trying to get my late grandfather's truck back in working order.


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The 3310 is too much carb for your 305. I know that's not what you want to hear. Sounds like your accelerator pump's shot by the description of the stumbling problem.
Or this place has good carb prices & Lifetime Warranty. Look at the M4ME, M4MED, or E4ME to ID your carb > http://www.nationalcarburetors.com/cat-chevytruck.html

the most painless method.. and not all that expensive..
would be to use an Edelbrock Performer intake (about $130 new)

http://store.summitracing.com/partd...01&autoview=sku

and a holley 4160 600cfm carb ($255)
http://store.summitracing.com/partd...15&autoview=sku

that should be just about right for a 305. my 600 is just a tad small for my 350..


before anyone accuses me of pushing edlebrock manifolds.. I like them because they're made in the USA and I've used both the Performer, and the Performer RPM, and soon the RPM Air GAp manifold

Remember when you get rid of the computer controlled carb you´ll have to ditch the distributor as well and get a non ECM one, or you´ll have no advance.

I was scared that I would have to make all those changes. Although, I appreciate all the insight.

pick up a POINTS distributor.. they're very cheap.. around $50-$80.. and then get a Pertronix FlameThrower kit.. it's better then a stock HEI :>

if you don't mind dropping some $$$... an MSD #8360 ProBillet "Ready to Run" distributor (About $300 i think) and an MSD Blaster-2 or Blaster-3 coil would be an excellent choice.

also check with your local parts store, they might have cheap re-man HEI's too.

couldn't you just get the spreadbore to squarebore adapter. I would run a 600 holley model 80457. It is what I run on my 351w and 390

He's got a TBI engine.. the best he could hopefor is a 2 bbl carb and adapter plate....

It's not a TBI. I have a qjet. I already have the adapter to put the holley carb on the spreadbore manifold. The holley I have is too big for the 305. I need to either wrangle a smaller carb and tear off the smog components or just wait and finish the 383 I am piecing together. But I would like to have the truck a little more driveable before I get the new motor finished.

the 3310 is a 750cfm vacuum operated carb (just like your current Qjet).

Your 305 will not open the secondarys all the way if it doesn't need it (just like your current Qjet). so, don't worry, the 3310 carb is not too big.

more important, is how to connect the carb to the linkages. (throttle, trans, cruise control, ect)

what kind of transmission are you running?

sounds like you need a shorter accelerator pump shaft on your Qjet.

i have a th350 in the truck.

Short of rebuilding it, you might try seeing what hole the accelerator pump lever linkage is in (say THAT 3X real fast ).

If it's in the outer hole, move it to the inner hole. This will give more fuel off idle.

You have to use a small punch to drive a roll pin to do this. Don't drive the pin tight against the air horn- leave room to slip a small screwdriver behind it to reinstall the lever.

Have you done the carb cleaner routine? Sometimes the stuff actually helps. If an orifice has gotten plugged it can cause a too rich a/f ratio.

While the electronic Qjet isn't a great performance piece, it should operate flawlessly in its stock application. I've had a few and they were just dreams for cold starting, and daily operation.

Have someone rebuild it.... even you can do it. The carb rebuild kit comes with how to bench set the carb to run great, then you fine tune it on the truck. Many times people have a carb that stops running right, so they start "tuning" it and get it all out of whack. There is nothing about the "tune" that has changed. The engine is the same, the carb's physical features like jet and rod sizes are the same, its nothing about the tune that has changed. What has most likely happened is that the inside of the carb is full of gunk, the accelerator pump wore out, the throttle shaft has play in it, and the needle and seat aren't sealing properly anymore.

Just rebuild it. Think of it this way; you currently have a matched carburetor that is out of tune. So rebuild it and tune it. Your other option is to put a large carb on it that is way off for your engine. You'll be chasing down its tune for months and may never get it right. Why not just start with the carb that's right for your engine?

Is this a full electronic Q-jet or does it just have the one solenoid that limits the amount of pump shot after the truck warms up ? A 750 vaccum secodary holley should be okay on a 305. If the truck bogs at all stiffen up the vaccum spring. Personally I would keep the Q-jet. As far as the sputter goes are you sure that it is a carb problem ?

a 750 holley would NOT be ok for 305

while it's true the secondaries won't open up.. the larger diameter primaries would cause the air velocity in the primaries to get too low, and cause poor fuel metering and poor driveability. I tried a vac secondary 750 on my 350cid and it was horrible compared to my 600. the only place it accelled was at high rpm @ wot.

get yourself a 600cfm 4160 (list #1850) I don't knwo the holley part # off hand.