Carb Question
- Thread starter giowest
- Start date
mopar_man
Good time party boy
You'll need a number off the base on one of the mounting ears on the front, Gio. There's 3 sizes. 800, 850 and 1000. Doc has told me how to tell the difference and I think I have the numbers right. The primary sizes are:
800: 1 3/8"
850: 1 1/2"
The 1000 CFM version would be obvious I think
800: 1 3/8"
850: 1 1/2"
The 1000 CFM version would be obvious I think
Da-ho
not even
I dont remember what cam and compression ratio you have in this one but generally for street use spread bore is the way to go. Highest vaccum and best throttle response regardless of internals usually. Used T-quads are an untried entity but when you find a good one nothing even comes close. When you go through it fill the float bowl area with gas and ckeck for leakdown through the metering rod pockets where its glued together and reseal that seam with fresh epoxy. Its a close fit to the baseplate but required. Use a straight edge to check for warpage on all mating surfaces. Ive had the best luck trueing up the bottom of the base plate only and let the rest of it be. Throttle shafts can be bushed just like a Q-jet when they are worn enough to suck air. Same adjustment on the upper doors on the secondary side as a Q-jet also. As far as Im concerned they are the best street carb made and the float bowl area doesnt seem to mind running blended fuel although some guys say otherwise.
Dr.Jass
Pastor of Muppets
The nice thing about the TQ when running blended fuel is that, on average, the fuel stays 15°-20° cooler with the plastic float bowl. Blended fuels have a lower RVP than good ol' straight gasoline, so they tend to evaporate more easily which can cause vapor lock.
Tuning the TQ is easy enough, and the factory jetting on HP carbs like yours hits a pretty wide target... but if your engine falls outside the range that jetting can cover, tuning parts can be a pain to get. Really, if you're not too wild, simple secondary air-door tension and idle-mixture adjustments are about all you'll need to make. Lean-Burn era carbs can benefit from some jet drilling and metering-rod filing (or grabbing tuning parts from truck/muscle-era carbs)
Tuning the TQ is easy enough, and the factory jetting on HP carbs like yours hits a pretty wide target... but if your engine falls outside the range that jetting can cover, tuning parts can be a pain to get. Really, if you're not too wild, simple secondary air-door tension and idle-mixture adjustments are about all you'll need to make. Lean-Burn era carbs can benefit from some jet drilling and metering-rod filing (or grabbing tuning parts from truck/muscle-era carbs)
Dr.Jass
Pastor of Muppets
9379S = 1983 truck 360 carb; the wire on the back is for a bowl-vent solenoid. It's an 800s, but it's probably a tad lean for your 360, Geo... OK, probably a bunch lean.
One thing to remember, too, about ThermoQuads: if there's no small hose nipple to the right of the right idle-mixture screw as you look at the front, it has no ported vacuum as needed for vacuum advance distributors. That 9379S should have one, being a truck carb, but no guarantees.
If I were you, I'd go with the 440 carb; the jetting is probably OK for your engine on that one.
One thing to remember, too, about ThermoQuads: if there's no small hose nipple to the right of the right idle-mixture screw as you look at the front, it has no ported vacuum as needed for vacuum advance distributors. That 9379S should have one, being a truck carb, but no guarantees.
If I were you, I'd go with the 440 carb; the jetting is probably OK for your engine on that one.
Dr.Jass said:9379S = 1983 truck 360 carb; the wire on the back is for a bowl-vent solenoid. It's an 800s, but it's probably a tad lean for your 360, Geo... OK, probably a bunch lean.
One thing to remember, too, about ThermoQuads: if there's no small hose nipple to the right of the right idle-mixture screw as you look at the front, it has no ported vacuum as needed for vacuum advance distributors. That 9379S should have one, being a truck carb, but no guarantees.
If I were you, I'd go with the 440 carb; the jetting is probably OK for your engine on that one.
Thanks for the info Doc, Think I'll stick with the 850.
Da-ho
not even
Yep- thats the one. Raised rectangular areas with stickers on them. Almost afraid to dip it in case they melt off. Throttle shafts are getting sticky, havnt ran it for 10 yrs or so. It came in on a built small block. No numbers on the base and thats what has always threw me as far as IDing it. It always worked fine- never had it apart.