Author Topic: rebuilt Q jet base plate question  (Read 2891 times)

Offline rhino33

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rebuilt Q jet base plate question
« on: September 05, 2010, 05:06:55 AM »
when I ordered my carb, the remanufacturer assured me that all areas would be covered.
when I got it , I was expecting to see bushings in the throttle plate and there are none.
the tp looks like new to me
there is some wiggle room on the shaft, is this normal?
also when I back out the mixture screws to 5 turns out, it seems that the screws are VERY sloppy, almost ready to fall out of their holes, is this normal?
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Offline Cliff Ruggles

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Re: rebuilt Q jet base plate question
« Reply #1 on: September 06, 2010, 06:03:03 AM »
It should have very little play at the primary shaft.

What is the carburetor number?

The mixture screws should end up about 2-4 turns for early models, and 3-5 turns for later models with the metric threads, for most set-ups.....Cliff

Offline rhino33

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Re: rebuilt Q jet base plate question
« Reply #2 on: September 07, 2010, 02:39:14 PM »
17057263 77 pontiac 400 manual
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Offline Cliff Ruggles

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Re: rebuilt Q jet base plate question
« Reply #3 on: September 08, 2010, 04:39:26 PM »
Very good unit, identical to the one that's on my own engine.  Plenty of potential there, it may need some minor tuning for what you are doing?

If it's commercially "remanufactured", it's probably going to need some help anyhow, just to work correctly.....Cliff

Offline rhino33

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Re: rebuilt Q jet base plate question
« Reply #4 on: September 08, 2010, 05:48:20 PM »
I bought my car with this 1975 400 engine already in it and not running, the cam is unknown, pulling 20hg at 800 rpm, when i replaced the oil pan and rear main, I could see aluminum pistons, rods all ground but one set, crank does not have the knurl at the seal area and seems as if the counterbalancers have been machined into the drillouts.
this engine has been doing so many different things that I needed to nail it down before we could discuss any improvements.
I have 70 main 42 primary rod
I changed out the new power piston spring for a weaker one
seems a bit starved for fuel off idle and at cruise, but close to running right
what do you recommend
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Offline Cliff Ruggles

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Re: rebuilt Q jet base plate question
« Reply #5 on: September 09, 2010, 02:49:39 AM »
I'd install larger jets and a set of our custom primary metering rods.  Then adjust the APT to fine tune the primary side A/F at part throttle. 

It also sounds like you need to open up the idle system a bit as well, which can be done while the top is off the carb. 

Our book covers how to set them up for larger cams, etc.....Cliff