looking for a quadrajet guru

[chris650]

Hello. I am looking to for somebody who has extreme knowledge of the inner workings of Rochester quadrajets. Please reply if this is you!

 

[Bondo]

Re: looking for a quadrajet guru

Hello. I am looking to for somebody who has extreme knowledge of the inner workings of Rochester quadrajets. Please reply if this is you!

Ayuh,..... Why don't ya get the ball rollin', 'n explain what's wrong,..??

 

[Eric 3.7LX Alpha 1]

Re: looking for a quadrajet guru

Ayuh,..... Why don't ya get the ball rollin', 'n explain what's wrong,..??

Exactly.... there are many on here who know Rochesters in and out...

what gives?

 

[chris650]

Re: looking for a quadrajet guru

ok gentlemen. What I am looking for is to rebuild my carb. I have two quads that are the same casting. One came off of my boat, and one is a spare. I want to use the body and the horn of the spare, due to the fact that they are in way better shape. Now im well aware of the safty issues involving the differences between marine and auto carbs. But I know for a fact that places like National Carburetor for example, are selling re-furbished carbs that were once automobile carbs, but have been modified, and they are selling them as marine carbs. The carb that came off of my boat was one...when I looked up the numbers it showed up as a carb that was used on gmc trucks. Point being, if they can do it, I can do it. I am more interested in the internal alterations that im noticing when I place my two bodies side by side. Im noticing certain ports and holes have been plugged or dev-conned on the boat carb that are open on the auto carb. Was this done on purpose to make this a marine carb?? And if so, for what reason? And should I replicate these alterations on the new body?

 

[chris650]

Re: looking for a quadrajet guru

In a nutshell...I want to know everything I need to know to make this auto carb a marine carb. Its going on a 260 merc. From what modifications I need to do, to what I need to dev-con shut, to what jet and needle combos are the best.

 

[chris650]

Re: looking for a quadrajet guru

Here are a few pics. The arrows are pointing to just a few of the differences.

 

[chris650]

Re: looking for a quadrajet guru

Carb off my boat is on the left

 

[chris650]

Re: looking for a quadrajet guru

Any input guys?

 

[chris650]

Re: looking for a quadrajet guru

Any input guys?

 

[jimmy wise]

Re: looking for a quadrajet guru

yea they arnt the same.....start by checking your base plate is it tight? is it just cosmetics or is you stuff corroded

 

[jimmy wise]

Re: looking for a quadrajet guru

also your carb on left has the epoxy because the press in plugs leak. that is right.

 

[funk6294]

Re: looking for a quadrajet guru

Looking at the two the slot for the secodary hanger is different for sure. To make a carb marine it typically has the float vent angled into the the venturies to prevent any spillage on to the motor or bilge. They also change some of the fuel circuits. Specifically I am not sure, but I would be looking at the differences in air bleed sizes and accelerator pump nozzles to start. If you are having issues with your current carb being worn out, why not id the worn parts and repair. If it is the throttle shafts getting sloppy there are bushing kits to tighten that up.

 

[chris650]

Re: looking for a quadrajet guru

not looking to repair the body due to deterioration of gasket surfaces. Both bodies have the exact same vacuum holes. The difference is that they have been intentionally plugged shut in the one body that came off of the boat. Why?? There must be a reason for doing this! Safty issues and modifications I am well aware of and stated earlier that I am not asking about those. I want to know about the modifications that are done for performance reasons...and why they are done.

 

[chris650]

Re: looking for a quadrajet guru

Maybe I can explain myself differently....and this is directed at any of you on this forum who have done a lot of these carbs. Lets say for example a friend of yours comes to you and says his quadrajet on his boat is worn out. But he picked up another one and its in great shape, only thing is, is its off of a car. So he asks you if you could do the modifications needed to make it a marine carb. Ok, so you have it apart...what are you looking for, what are you altering,plugging etc...and why??

 

[chris650]

Re: looking for a quadrajet guru

anybody?

 

[NHGuy]

Re: looking for a quadrajet guru

iii

 

[NHGuy]

Re: looking for a quadrajet guru

I got this. "How to Rebuild and Modify Rochester Quadrajet Carburetors" by Cliff Ruggles. This guy has forgotten more about qjets than the guys that designed them. Plus he has every part and knows the castings and their interchanges.
You can sign up for his forum at cliffshighperformance.com.
My carb was goofed up, had a leaking vacuum breaker, and I just felt it wasn't perfect. After I redid it, wow. It acts like fuel injection.

Those gasket surfaces can possibly be saved, show em to Cliff. Then you have a marine carb, jetted and vented for your boat engine.
In his book I recall a part where he showed how to fix that kind of corrosion.

 

[chris650]

Re: looking for a quadrajet guru

thank NH! I am going to check out his forum!

 

[chris650]

Re: looking for a quadrajet guru

The point of me finding out the info I seek is to learn though...so using the new body is no problem. Ive been a machinist for over 20 yrs and have a whole shop at my disposal. Hell...I can make my own brass vents no problem. And im sure the gasket surface is shot...cracked and separated where the countersinks are, that hold the horn to the body. So hopefully this forum you suggested will provide me the info I want. Like I said, places like national carburetor do this stuff everyday. The learning experience is what I seek!!

 

[NHGuy]

If it's the same casting number just use the jets and rods from the marine carb and copy the vent entry on the front so there's a place for the fuel tell tale. But use Cliff, he's a willing helper. I'd say test the vacuum break, get a rebuild set and a pair of down tubes and tear it down. Those tubes only cost a few bucks and they are at the bottom of the main casting. I did mine because I think they were holding in some crud.