It was suggested to me to eliminate header flange leaks, that I remove the 3-bolt flange from my headers and weld on a ball-&-socket connection. I purchased the ball & socket adaptors from Walker Exhaust; PN41723 & PN41726 $8.99ea. I'm also installing a pair of 300-cell, Magnaflow catalytic convertors. I was planning to install the cats after the ball & socket joints and weld them to the exhaust pipes, but this moves the cats too far back such that they will be directly beneath the trans crossmember and there won't be enough clearance. Here's a pic.




If I move the cats forward (switching positions with the ball & socket joints) there will be plenty of clearance between the ball & socket joints and the crossmember, but the connection between the header and the cats would be a slip joint. Anybody see a problem with this approach? Here's a pic:




I've read that moving the cats forward will help them light-off more quickly, making them more effective. If I ever have to pull the engine, I would need to disconnect the ball & socket joints and then remove the cat from the headers - assuming I can pull the engine with the headers still bolted on. This is my first rodeo with headers, so maybe this isn't possible. Looking forward to your comments and suggestions.

 

What is the part number on those cats, they sure are compact. The best way to pull the motor is unbolting the headers at the cylinder heads and tying them to the side to reinstall the engine.

 

If you are working on the car in your avatar, why would you put cats on it? Just curious.

 

I would cut off the 3 bolt flange and weld the socket joint so its in the same spot. Weld the other side of the socket joint to the cat as such to clear the xmember.

 

The part number for a 2.5" in/out is 779-40025. They are 4" diameter with a metal matrix core, rated at 396cfm each.

 

This engine is going in my '72 convertible project. I want to reduce the exhaust smell to make top-down driving more enjoyable. Here's a link to my project thread:

https://classicoldsmobile.com/forums...nvertible.html

 

Proper selection of carb jets will preclude exhaust smell. If you pass an overly rich mixture through cats, you get the rotten egg smell. I've never gotten exhaust smell in the passenger compartment of any convertible I've ever owned. The only issue would be if you had the top up with back window unzipped and the side windows up. With the top down, nothing.

 

I agree with Joe. If you're getting exhaust smell in your convert something is wrong. Check your exhaust for leaks. Anyways a cat will only make the exhaust smell worse.

 

You have to be careful with cats on a non feedback carbureted fuel system. I have seen older carbureted cars with factory cats run too rich and make the cats burn red hot. A few times the carpet padding started smoking from the heat through the floorboards. You will need to fabricate some heat shields between the cats and the floorboard if you decide to move forward with the cat install.

 

If you're not planning on doing the work yourself, I would take them to an exhaust shop and have them knock it out. They probably won't use all the pipe that's on that cat or the flanges. There's a guy I've gotten a few sets of flanges from that now lives down here in south Florida.


If you send the guy an eBay message with your phone number, he will call you back. He makes these things out of anything you want with any dimension you want. The walker stuff, I'm sure is great, but you need to be able to weld it and expand it yourself.


https://www.ebay.com/itm/2-50-CUSTOM...FRB~3C&vxp=mtr

 

Agreed.

I cut the flange off my headers and then welded the "male" side of a Flowmaster ball flange to them. You could probably put a slip flange on the converters you have, and then expand the converter pipe to become the "female" side of the ball flange, and return the 41726 parts.

Another flange just after the mufflers (if room allows) would allow you to drop the whole mid section of exhaust for more room while working under the car.

 

Gary:
I'll be running a FiTech throttle body EFI, not a carb, but the O2 sensor will be prior to the Cat, so no feedback. I know multi-port EFI is better, but can the FiTech system control the mixture well enough to run the cats safely?
Rodney

 

I noticed today that my header flanges are not pointed straight back; the passenger side is pointed inward. Is the RH header pointed inward for a reason or is this just poor manufacturing QC? I expected both flanges to line up and be parallel to the bell housing surface of the block. This is my first rodeo with headers so I'm a little unfamiliar with how things should look. Here's a few pics:



The passenger side is about 15 degrees out.




Passenger side.




Drivers side.

 

I'm on board with Joe and the others. 20+ years of driving the convertible and no issues with exhaust smell in the car with the top down. If you are having issues there's something wrong that needs to be addressed.

 

Don't worry about the angle if you're using those ball flange connectors. They can be a little off and will still seal

 

x2, should not be a problem.

 

Is it normal for the flanges to be so far out?

 

What brand headers are they?

 

They are Hooker 3901. 5/8" primary tubes with 2-1/2" collectors.

 

Call Hooker and ask, kinda curious myself.

 

I believe it is normal and I believe Hedman's are similar. I can't remember if my Flowtech's were the same.