Rebuilding a carb for my Pontiac 350 - 17058253

[sixth_sense676]

Howdy folks,

First off, great site. Thanks very much Cliff, for making this forum and being such a great help to us all!

I have a Pontiac 350 being built, with #46 (72cc) heads. The intake valve has been enlarged to 2.11, screw in studs added, etc. I will be running a Comp XE262 cam, headers, and 2.5" true dual exhaust. The intake is from a '68 GTO, and I will be using the Shaker Assembly that came with my car.

The Carb I have is a 17058253, which comes down to a 800cfm '78 Olds carb, non California std. I would like to rebuild it myself, but have never rebuilt a carb before, and was wondering if you could help me answer a few questions.

Is the 17058253 a good carb, or should I look for another?

If it is a good carb, what rebuild kit should I get for it? I cant seem to find kits for this specific carb.

Any tuning/rebuilding/jetting suggestions?

It will be used mostly about town, and the occasional road trip. It will be my daily driver. Id like to get decent mileage (18-22mpg if possible) on the primaries, but also be able to put the fear of God into a ricer when the secondaries open up.

Thanks!
 -Derrick

[Cliff Ruggles]

Excellent starting point for what you are doing.  Even though the later Old's unit is emission calibrated, they just need a few minor modifications and they are fine.

We stock complete HP kits, and the correct tuning parts to set it up exactly for the application.  When you get time, call the shop and we'll get what you need headed your way...thanks....Cliff

[sixth_sense676]

Great! Thanks Cliff! Give you a call in a few days.

[sixth_sense676]

Just received my HP kit today. Very fast shipping, high quality parts, and packaged very carefully! Thank you!

Hope you don't mind if I bug you with questions along the way, never rebuilt a carb before and this q-jet looks complicated.

Again, thank you very much! I will keep you filled on my progress, for sure.

[sixth_sense676]

I started taking my carb apart today, and noticed that I have no aneroid assembly in the hole - just some little plastic insert. Sorry to sound so amateur, but is that normal?

I ordered Cliff's book about a week ago, hopefully I will find all my answers in it, but until I get it, I need to bug you guys! Sorry about the bother and thanks in advance!

[omaha]

yes, this is totally normal for that carb. I guess the short lived '75-'76 APT could be called an "aneroid" but  I thought it worked with the engines vacuum. (neg pressure??) anyway' when GM did away with this early system, they decided to just put in a plastic cup in place of the device. they did not change the outward appearance (maybe they were thinking about the computerized carbs and its associated solenoid placement way back in 1974). In all reality, it is fairly hard to find a carb with that old APT system. I have found only one so far. I also havw found regular apt "Mod-quads" that had build dates in 1975 so not even all 1975 carbs had the "aneroids".  your carb (should) has the newer style APT with the adjustable step for the power piston.  This is a much better set-up (obviously since the earlier one went away in less than 2 years) It works much better. ...........Don't worry, it;s good!!

[sixth_sense676]

Thanks so much! That's a relief.

Book still hasn't arrived yet, so another question...

How much play is too much play in my throttle shaft? I can wiggle them both a tad, back and forth, as well as in and out. Do I need the bushing set, or am I ok?

Thanks again,
   -Derrick

[sixth_sense676]

I finally got the book! After looking I decided it would probably be best to go ahead and buy the shaft bushing kit. I need to get some parts for recipe #2 anyways. I want to do this right the first time.

 Just curious, after you sand blast all your parts, do y'all nickel plate them or what do y'all prefer to do? Since its getting blasted inside and out I ruled out carb renew paint - as carb renew wont protect the inside.

[omaha]

   If you have a local chrome plater in your area, ask if he has any experience plating carbs. Usually this is some kind of zinc-chromate process.  Not that complicated cpmpared to chrome, just a protective plating. Original carbs were just "washed' with some kind of chemical (dont rermember what) and this reacted to the various metals in the carb. Early carbs were darker 'cause they had more lead in them. later ones were lighter. It takes some ptactice to get the correct look, that is why it is bect to go with a guy that has some experience.
   There might be some other types of plating that would work on the carb that might look good but that would be another question for the plater person.
    As far as paint goes, I think the only type of paint that I have seen that has any lasting durability on a carb would be Dupont Imron. ($$) I have also seen some carbs that were powder coated. this process is also often done at the same plating shops.  I do not knpw if powder coating is affected by gasoline so you will have to look into this. but I have seen this done.
         I always wanted to try black chromate plating. It looks sweet BUT at 20 dollars a pop to try it, the plater has not tried this yet and cannot garuntee how it would come out. Any way good luck!!