Hey guys.

So I successfully got this thing from UT to TX in one piece, but now I can barely get it to idle. Came from 4700 miles down to 425 miles above sea level, so I'm assuming that's most of the problem. I've always heard I should go about two jet sizes down, but I'm having a hard time finding any info on whether or not I should change any of the metering rods? Forgive me if this is a dumb question, I'm from the EFI generation so all this mechanical wizardry is hard for me.

Hopefully when I have more money I can get a wideband and do it properly, but at the moment my only other vehicle is halfway across town with a blown water pump, so that's not in the budget yet.

Thanks.

 

I'd start by just retuning everything. Where in Texas are ya?

 

Blast. Makes sense, but I'm always looking for an easy way out

Waco. Super cheap houses down here, and we work online.
Edit: So you're only a couple of hours away? That's pretty sweet - never been anywhere near another member before.

 

In the old days these cars were all made the same. People tuned them to there environment.

Waco is not very far from here and there is a very active Olds club (North Texas Olds Club) in the DFW area. Great bunch of folks.

 

I'm tempted to use this as an excuse to try a new fuel setup, my Q-Jet base is a bit warped and the hinge for the accel pump is broken. Plus, as good as a Q-Jet can be when set up right, I've rebuilt it 13 times, tried every setting on the stupid secondaries... it just never seems quite right. Need a wideband and a wizard.

 

Gotcha. Starting to do some homework but having a really hard time digging up any tuning info for the Q-Jet, would you happen to know of somewhere I should look?

Awesome! That's good to hear - I was the only '70 C body in Utah maybe I can finally find a front end to replace the one my uncle ran into a telephone pole.

 

Double check your dwell (if applicable), set timing, and reset the A/F mixture screws to start. Basically perform a tune up without replacing parts.

 

So you went from heaven to hell, no wonder you're having problems!!! ;-).
You probably have different gas as well. You'll need to address the things already listed.

 

4700 miles and 425 miles above sea level....thats your problem no oxygen for combustion! Hell the SR71 flies(flew) at 80,000 feet, thats 15 miles above seal level...lol. My bet is the timing is retarded for the 4700'.
Get your self a vacuum gauge, hook it to a direct intake manifold nipple and tweak the A/F mix, and base timing to achieve the highest vac reading possible. Dwell set at 30* or .017". Make sure theres zero vacuum leaks. Start there get back to us.

 

Awesome, thanks. I'll get on that, keep you posted.

 

Depends on who you ask

Same gas, pulled it on a trailer.

 

I'll check that out too - did the dwell and everything right before I left, but I've always had issues with getting the timing right. Maybe it was set up for sea level the whole time and my high-elevation adjustments just screwed it up.

 

Sqeek, what carb # are you running? I may have a top plate and base if needed. Just down the road in Marble Falls. (Paradise)

 

Not completely sure, I've always had a hard time figuring it out. Original '70 Q-J with mechanical secondary and choke, I'll take a closer look later. I would love to buy those off you if they fit!

 

Got it running:
- Increased idle fuel screws by ~30% or so
- Increased idle throttle screw to get it started
- Took a tiny bit of dwell out to get it to 30*
- Timing was a bit retarded, set to 10*BTDC@1Krpm, maybe a tiny bit under, didn't want to blow it up first try
- Used vac gauge to set idle mix screws, had to increase quite a bit for stable idle, warped carb base impedes idle adjustment a bit but got it between 600-650

Thing runs better than it ever did in UT. Smells rich as hell now for some reason, still not perfect, but at least it moves. [have to use it to tow the Jeep home, it's sitting across town with a shattered water pump] - interestingly enough, stays a bit cooler too. Should've moved down here sooner

Thanks for the help.

 

Well, I found this core for a 70 350, 7043250. It's not locked, $75.
Let me know if you can use it or not. You could probably use your
7040257 center section with this top and bottom plate easy enough.
You would need to use your hangers and needles though.
And someone will want the center part from this one to use possibly.
The fuel inlet threads are in good shape as well.

 

Looks good! I have to buy $1500 of parts for the Jeep [never buy one] but give me a couple of days to figure out my finances / compatibility and I'll let you know. Thanks!

 

Be cautious with swapping major parts (base, body, airhorn) between carbs. The hole configuration between base and body changed several times, and sometimes it's very subtle. At least those parts tend to stay flat.
I would never swap an airhorn (again). Every qjet I've seen (30+?) has warped, significantly, as just part of the horrors of life. Each one warps differently, so getting a different airhorn to seal to a different body is quite hard. And the configuration of airhorn/body holes changed quite a number of times.

Good cores can be found, particularly for '73 and later. You can use any year qjet other than the computer controlled / solenoid ones, but those didn't show up until the 80's. Do expect to tune any core.

There's a book by Doug Roe which is a really good tech reference, particularly for state-of-the-art in the 80's. Cliff Ruggles wrote a more recent book with a somewhat different viewpoint but includes newer techniques and much better pictures. Tuning qjets is a maze of twisty passages. Same for any carb, really, but parts availability for qjets can be a bit of a problem.


Gas at high altitude (>2500' or so seems to be where it starts) is a few points lower octane since the air is a little thinner. Not a huge problem having that gas at lower altitude, just don't drag race on too-low octane since it may ping.

I've enjoyed having a wideband, but tuning can certainly be accomplished without one. You won't get perfect A/F readings from a carb, anyway.

Ensuring the basics - no air leaks, strong reliable ignition, stable ignition timing - can fix many "carb" problems.