Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - Rochester Quadrajet 4MV Carburetor: Removal, Disassembly, Rebuild (Rookie Level)
View Single Post
  #51 (permalink)  
Old 03-02-2011, 05:32 PM
lt1silverhawk's Avatar
lt1silverhawk lt1silverhawk is offline
"But how do it know?"
 
Last wiki edit: How to rebuild a Rochester Quadrajet 4MV carbureto... Last photo:
Join Date: Mar 2010
Location: Lakewood, CA
Posts: 2,287
Wiki Edits: 132

Thanks: 104
Thanked 24 Times in 17 Posts
Quote:
Originally Posted by cobalt327
I've been saying that about using JB Weld forever. Then I hear back, "Ruggles uses Marine Tex epoxy". All I know is, epoxy has failed in the past and I will not use it on my carbs. And I'm glad to hear he seems to think that, too.
Quote:
Originally Posted by TommyK
BTW he recommends Devcon Marine-Tex epoxy as the only permanent well plug sealing material he has found.
I list these two quotes only because two different views have been given by two members in this particular thread. Two clear up any confusion, I'll mention what I have found: although Ruggles makes no mention of Marine Tex in the book, he certainly carries it as a part of the Bottom Plug Kit. He also recommends it on his forum. So although he is using epoxy, it is conjunction with the screw-in plugs.




------------------




Quote:
Originally Posted by cobalt327
I cannot see the gap, so I cannot offer an opinion- but if it's significant, you'll want to either replace parts, or... I suppose sand it down. Although I will readily admit to never having done this. That said, it sounds easy, but somehow I doubt it actually IS easy. At least not to get it perfectly smooth and square. But that could be just me.

In any event, this means removing the down tubes from the airhorn (unless, God forbid, you want to sand on the main body ). Measure their installed height before removing them, and be careful when you remove them.
The gap seems very small, so much so that the camera may not even pick it up. I went back and reread the section on sanding and machining. The airhorn and the base plate can be sanded down "to conform to the main body and prevent leaks at the top gasket." (chapter 4, page 68). The book also mentions that the main body can be machined flat, but it "lowers the power piston the same amount that is taken off the main body and can affect carburetor function." This isn't considered cost-effective unless it is a rare or valuable carburetor. (chapter 4, page 68).




Quote:
Originally Posted by cobalt327
I don't know what procedure he uses for this. If you would, post what it is. I would insert a solid piece of wire the same size as the ID of the tubes into them so they could be gripped w/o crushing them.

The inner tubes are bottlenecked on the bottom, so you will want to go in from the top w/the wire "reinforcement", should you try to remove them this way. The inners are also small, it may take a bit from a numbered set to do it, or maybe a cut down pin, etc. Make sure the end of the wire extends out of the tubes, after gripping them for removal the wire will be trapped and you'll want to be able to grip the wire for removal.
I am confused on this one. Are you taking about the brass tubes in the air horn? I didn't find a procedure for those.




Quote:
Originally Posted by cobalt327
All that said- unless there is a gap that will not close up when the screws and bolts are tightened, don't worry about it. They mainly will be warped downward at the corners where the long bolts go through the airhorn down to the intake flange. These get overtightened, and the corners will 'droop'. Unless this is bad, I usually do nothing. I have had to VERY carefully tweak the corners back up some- but this always makes me nervous, cast zinc is brittle.
To my untrained eyes, I'd say the gap is very minor so I won't worry about it.




---------------




Quote:
Originally Posted by cobalt327
You want them to be 90 degrees. Yours aren't.
Alright, time to do some linkage bendin'.




Quote:
Originally Posted by cobalt327
Do not drill the throttle plates unless as a last resort. If your cam isn't radical (I don't recall any specs on your engine, sorry), this won't be an issue anyway. The more duration/overlap, the more need there is for the bypass air, but there are other ways besides drilling the plates to accomplish this, same as a Holley.
The engine is a bone stock, crate 350, so nothing special or radical here.




Quote:
Originally Posted by cobalt327
I got a chuckle out of using a machinist rule to hold the PP down in position while reassembling the top of the carb to the body.

My thoughts on this are that it's bad enough already- you have to keep the gasket in position while the return spring of the accelerator pump piston is fighting to extend, plus aligning the down tubes into their proper positions, and at the same time you're aiming the pump through the hole in the airhorn, etc.
I agree. The retainer on my particular carb is no good and I will buy the bushing. But for future reference, I do want to mention that I was able to hold it in place using the gasket between the air horn and the main body. Ruggles seems to be doing the same thing in the picture accompanying the procedure in the book. (chapter 5, page 84).




Quote:
Originally Posted by cobalt327
I would do most anything to not add yet another procedure to all that- you'd be running short of hands, I think! lol
Lol! Point taken!
Reply With Quote