Best Way To Repair Butterflies

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bobscuda67

bobscuda67

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May 650 Edelbrock carb has holes drilled in the primary butterflies from a previous cam install and now I want to repair them. What's the best way? Rivet, nut and bolt, or silver solder. Maybe epoxy? Of course the best way is just buy new ones but I can't find anyone that sells them.
You people with sharp eyes will see that my port sync is almost closed which is the reason for the repair.
DSCN0771.JPG
 
Many rivets are hollow, so if you install a hollow aluminum rivet you should be able to drill out the center and leave the outside part of the rivet in place. I've drilled out many rivets and I'm always amazed how the outside section of the rivet "NEVER" wants to come out!!! If you do drill out the inside part of the rivet and the outside part gets loose (which is what usually happens) simply use a hammer (or a punch in a vice) as a "back up" and another hammer to peen the outer part of the rivet in place.

treblig
 
Solder!
Cuz IF, it falls out, it is more likely to pass thru the engine harmlessly.
But I've never gad solder fall out.
I chamfer both sides of the hole first, almost right down to the center of the material. I clean it, install a pellet,Crimp it in, and hit the plate with the heat, until the solder crawls in and makes a clean bond; one caveat, aluminum has a very low melting plate! When using a butane pencil-torch,keep it moving. I have used an electric gun as well, but it takes a long time to get the heat in there.

On another note,your sync looks pretty close, perhaps a tad small, but close. What rpm were you achieving at what idle-timing, and what are your cam specs and displacement.
But yeah, those holes are pretty humongous,lol. I had a 292/508 cam in my 11.3Scr- 367 for one summer, and it did not need that much bypass with just 14/16* of idle-timing.That was a 750DP. I'm still running that carb,now with a 276/110cam,10.9Scr, and the holes are soldered shut and filed nearly flat.
 
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I would use a steel semi-tubular rivet. Part number
MS16535-xx . The xx is the grip length or clench depth.
Does require a special setting tool but, they are cheap and can be found on ebay, as well as the rivets.
 
Does it effect the way it runs ? I wouldn't fix it till you try it.
And if you need to fix it I would replace them, they are out there and cheap.
 
Hey AJ, yes the holes are 1/8 inch in diameter.
My idle speed is 700 rpm in gear and the initial is 14* on a 372 displacement and the cam is a Lunati VooDoo 702 cam. Idles at 19 inches of vacuum.
The idle adjustment screws are 21/2 turns out.

Yes the best way is to replace them but I have been looking and I can't find any. Was going to call Edelbrock tech line to see if there available. If you have seen them let me know where amd Ill buy new ones.
Thanks
 
bobscuda67 said:
Hey AJ, yes the holes are 1/8 inch in diameter.
My idle speed is 700 rpm in gear and the initial is 14* on a 372 displacement and the cam is a Lunati VooDoo 702 cam. Idles at 19 inches of vacuum.
The idle adjustment screws are 21/2 turns out.

Yes the best way is to replace them but I have been looking and I can't find any. Was going to call Edelbrock tech line to see if there available. If you have seen them let me know where amd Ill buy new ones.
Thanks
Click to expand...
Wait what?...Hang on a sec
...Convertor stall?

Firstly replacing the blades is every bit as much trouble as plugging them. Maybe more.

Is this your cam?
  • Advertised Duration (Int/Exh): 262/268
  • Duration @ .050 (Int/Exh): 220/226
  • Gross Valve Lift (Int/Exh): .475/.494
  • LSA/ICL: 112/108
  • Valve Lash (Int/Exh): Hyd/Hyd
  • RPM Range: 1400-5800
  • Includes: Cam Only
Part Number: 10200702
Previous Part Number: 60402

If yes, then I see that you have traded away Transfer slot exposure to crank out the mixture screws to 2.5T, so you can run 700 in gear with 14* initial while utilizing those big ol' holes.
And I bet you get a big ol' clunk when you put it into gear cuz the no-load idle rpm is 850 or more.And I bet you are having trouble with a tip-in sag.
But the big clue is the 19" of idle vacuum.
So yes, those holes have got to go.
After they are gone, you can up the T-port exposure and return the mixture screws to about 1.5. This will bring the idle speed down and improve both the idle quality and richen up the tip-in, and maybe you can take out some pump-shot.The idle vacuum may not change much. Then maybe you get a lil wiggle room to run a bit more initial, altho with a 372 this is hardly an issue. I would actually be retarding it some more, for a slower idle. But I would run a really early-starting advance curve, so that by the top of the stall speed, it is back to normal..
Now getting back to replacing the blades
No easy task. Those screws are staked in there and possibly loc-tited in. So first you have to completely disassemble the carb more or less to get the baseplate off. Then you have to carefully drill off the staking with a really sharp drill-bit, so you don't have to press hard enough to bend the shaft. Then you have to flip it over and see if the screws will break loose. But the tiniest bit too much force and the screw-head breaks off and then the fun begins. So to prevent that I just heat up the screw heads to start with to relax any locking agent that may have been used. So get this; the torch is already on the bench,lol. Ok so say you get all 4 screws out without breaking any of them. Now you drop the blades out one atta time and swap in the new ones. Then you try and put new cranky tiny PITA screws. Ok so you get them in and snugged down. Now you gave to wiggle and jiggle and pilot theose blades into touching the bores all around, both sides and snug 'em up so they stay put for a bit. Then you check the t-port exposure to be sure they are sortof identical. If they are; then you take out one screw atta time and loc-tite it back in.Now, before the locking agent sets you still want to peen the ends like you found them, so they can no-way-no-how ever drop into the engine.And finally reassemble the carb. Reset the sync. Reset the mixture screws, And put it back on the intake,etc.
Maybe I'm just lazy, but I can drop a "lead ball" in there in a couple of minutes, no disassembly required.
 
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Unfortunately its a edelbrock so there is no removing the base plate, and they are loctited so heat is the way you have to go to get the screws out. Soldering will work but it is very temperature sensitive, to hot it wont work to cold it wont work, if you have a lot of experience with it it is easy if not it wont work. Like I said before if there is no driveability problem then don't try to fix it.
 
brian6pac said:
Unfortunately its a edelbrock so there is no removing the base plate, and they are loctited so heat is the way you have to go to get the screws out. Soldering will work but it is very temperature sensitive, to hot it wont work to cold it wont work, if you have a lot of experience with it it is easy if not it wont work. Like I said before if there is no driveability problem then don't try to fix it.
Click to expand...
Oh yeah, I flubbed that.
 
I have the butterflies out and it wasn't to bad. They have an interference fit and I backed them out slowly and can reuse them with some locktite.
The converter I have is Edge 91/2 2600 to 2800 stall and it works great.
 
bobscuda67 said:
I have the butterflies out and it wasn't to bad. They have an interference fit and I backed them out slowly and can reuse them with some locktite.
The converter I have is Edge 91/2 2600 to 2800 stall and it works great.
Click to expand...
Just make sure the screws stay put!
Ok 2600/2800 that should not be a problem as to rpm drop into gear.
Yeah, brain-fart, that's it. I seem to be getting more of those than I used to,lol.
 
Well I have them soldered and the mixture screws are 1 1/2 turns out and I have .040 of transfer slot showing. So basically back to where it was before the holes were drilled.
I used red Loctite on the screws and I also distorted the threads a little with pliers.
Thanks everyone for the help.
 
Starts almost instantly and idles at 650 in gear. There is no hesitation anywhere and the plugs are a nice tan color.
I don't know how you would make it run any better with parts that I have on it. I have been thinking about installing a wideband o2 sensor though.
 
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