I need something better than my Holley and I found this for sale off of an 85 C30 454. I see the electric choke thing and the idle up solenoid, does this appear to be a desirable version of the carb?
CK5
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Is this a good q-jet?
- Thread starter nvrenuf
- Start date
saved for reply after I look at mine in garage
That is about as good as it gets for the Q-jet models. It is a later, emissions version but can be modified for almost anything. It is probably a small block version since the linkage has provision for a TV or passing gear cable, the 454 was cut off at that point to clear the intake. That makes it even better in my book.
Right now I'm trying to avoid spending $400+ on an aftermarket performance reman carb so I can spend that money on tubing to finish a cage.
That is about as good as it gets for the Q-jet models. It is a later, emissions version but can be modified for almost anything. It is probably a small block version since the linkage has provision for a TV or passing gear cable, the 454 was cut off at that point to clear the intake. That makes it even better in my book.
I guess I need to ask for the numbers off of it to identify sbc or bbc version as I'll be using it on a 454. Would you still say it's worth getting since it'll be used on a 454?
If it isnt warped from being overtightened, or the throttle shaft isn't so loose as to cause a vacuum leak then it would be a fine builder and can be jetted to match any application. There are companies that sell jets, high flow needle and seats etc. You may want to pick up a good book on the q-jet and do some internet research before diving in.
I thought the 454's got the straight in fuel inlet?
Also, isn't your 454 TBI?
Martin
Also, isn't your 454 TBI?
Martin
I have read that bbc's have straight in fuel inlets but when looking at various perf carb sites all the pics show the 90° inlets for their bbc versions. Could be generic pics but it makes me wonder if the sbc versions can do the job if jet'd up and such.
As for my 454, it's carb'd (Holley 750). I eventually want to make the jump to TBI but I'll need everything as all of the original TBI is gone. Right now it runs so I want to spend big money on the unfinished areas (cage w/ possible full top conversion, front driveshaft, etc) to get the truck driving / wheelable for the spring.
Suggestions for q-jet books?
I liked Doug Roe's book.
There is no real difference when it comes to the carb bodies, other than the fuel inlet. That only matters if you want to use the stock steel lines.
Of course there is the 750/800 CFM casting difference, but I can't recall if the 454's exclusively got 800's or not...I tend to think not. The 305's in the trucks did get the 800's.
Either way, as Greg mentioned, they can be dialed in for whatever engine you use it on. There are literally thousands of combinations of rods, jets, floats, hangars, springs, you name it, that GM used on these things, to get maximum performance, tuning all of them to a particular drivetrain will be required.
There is no real difference when it comes to the carb bodies, other than the fuel inlet. That only matters if you want to use the stock steel lines.
Of course there is the 750/800 CFM casting difference, but I can't recall if the 454's exclusively got 800's or not...I tend to think not. The 305's in the trucks did get the 800's.
Either way, as Greg mentioned, they can be dialed in for whatever engine you use it on. There are literally thousands of combinations of rods, jets, floats, hangars, springs, you name it, that GM used on these things, to get maximum performance, tuning all of them to a particular drivetrain will be required.
Ok, with all of the jet / rod / etc combos in mind, would it be better to buy a cheap carb and build or buy a ready to run unit from someone like Jet or SMI? Obviously plug & play prebuilt units are easier but will I spend just as much building a used carb?
Are there any tell tale signs on a carb for the throttle shaft vacuum leaks or do you need to install it and check it while running with ether or..?
Are there any tell tale signs on a carb for the throttle shaft vacuum leaks or do you need to install it and check it while running with ether or..?
Anymore, I'd probably just say that ANY used Q-jet should have the primary throttleshaft bushed. Better safe than sorry. Sounds like that service is still around $40, if you have any local places that still do carbs, they might be able to accomplish that. Or you'll just pay shipping somewhere.
Rebuild kits on the low end are $25. To completely rebuild would want at least a float. There are some other potential wear areas, and a higher dollar rebuild kit may be in order, since ethanol is a problem now.
Still think you would be into one WAY less than ~$400 even if you bought all top tier parts and paid someone to bush it. Getting a good core (one that doesn't have a stripped out fuel inlet, or screws that were overtightened) is the only real concern IMO.
I've never spent the time necessary to really get them right (I guess Wideband O2 would be the way now) but I have played around with components to solve issues like lean surge after EGR removal, etc. At the time, the carbs were so prevalent that a trip to the local wrecking yard would net all the parts I'd ever need. Now, that probably isn't the case. Most people slap them on and call it good, but realistically that isn't getting as much out of them as is possible. There would be no different parts (or calibrations) if that were true.
Rebuild kits on the low end are $25. To completely rebuild would want at least a float. There are some other potential wear areas, and a higher dollar rebuild kit may be in order, since ethanol is a problem now.
Still think you would be into one WAY less than ~$400 even if you bought all top tier parts and paid someone to bush it. Getting a good core (one that doesn't have a stripped out fuel inlet, or screws that were overtightened) is the only real concern IMO.
I've never spent the time necessary to really get them right (I guess Wideband O2 would be the way now) but I have played around with components to solve issues like lean surge after EGR removal, etc. At the time, the carbs were so prevalent that a trip to the local wrecking yard would net all the parts I'd ever need. Now, that probably isn't the case. Most people slap them on and call it good, but realistically that isn't getting as much out of them as is possible. There would be no different parts (or calibrations) if that were true.
Lots of good info, thanks! I can get the carb for $50 + freight so I think I'll jump and learn how to build a q-jet. 
$50 for a used/unknown condition carb sounds way too much to me. I was used to paying $5 each at swap meets. I'd sell the ones I've got as-is for $50 every day of the week! (edit: not an ad, just stating that if you can multiply your investment 10x by doing nothing, you'd be crazy not to)
I used to build my own Q-jets for years, if you end up with that one and can't find someone to bush the shaft (if needed) let me know and I will try and find my tool and bushings. The last three carbs I needed i got from SMI, great products and service and they run as good as any I have ever had.
wasted wages
1 ton status
You will love that qjet over that 750 Holley ...
I went the same route and was much happier off road ...
And Q-Jets are pretty easy to work on once you do a few and get a hang of how they work...they are pretty tuneable with all of the aftermarket jets and metering rods..
Like others have said... Bush the throttle shafts or buy a base that has been bushed...start with a good baseplate and the rest is easy..start with a leaky throttle shaft and you will drive yourself nuts trying to tune it...
I went the same route and was much happier off road ...
And Q-Jets are pretty easy to work on once you do a few and get a hang of how they work...they are pretty tuneable with all of the aftermarket jets and metering rods..
Like others have said... Bush the throttle shafts or buy a base that has been bushed...start with a good baseplate and the rest is easy..start with a leaky throttle shaft and you will drive yourself nuts trying to tune it...
wasted wages
1 ton status
One more thing----follow the instructions on how to epoxy the soft plugs in the main body....I do everyone that I rebuild..I use JB weld and haven't had any issues...
COCHEV
1/2 ton status
Been my experience that the Buick carbs got the straight fuel inlet...
All the bb ones I've had were 90 degree like the small blocks
Hmm. I have a few big blocks with the straight inlet.
Martin
Martin
here's a complete dissertation on the venerable Q-jet clicky
some parts sites....
cliffs
Q-jet parts.com
Q-jets are simple to rebuild, other than reaming for shaft bushings. If you're not comfy with that you can have a shop do it.
And a BIG +1 on Doug Roe's book. It's a great resource for this carb.
some parts sites....
cliffs
Q-jet parts.com
Q-jets are simple to rebuild, other than reaming for shaft bushings. If you're not comfy with that you can have a shop do it.
And a BIG +1 on Doug Roe's book. It's a great resource for this carb.
