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  #1 (permalink)  
Old 03-24-2013, 07:21 PM
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Default how do you seal the tubes heading into the collectors?

So frustrated right now! Decided to switch to an EFI TBI unit on my GT, and finally got her running today, BUT....she is dumping fuel (super rich) and the AF ratio looks like 23 or there about....i know there's leaks at the collectors, so I think fresh air is being pulled in and the EFI is trying to dump fuel to get it in line....at least this is the only thing I can think of.

So, how can you seal the pipes into the collector? Is there a sealant?
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Old 03-24-2013, 08:02 PM
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Hey Brent, I use a high temp silicon sealant with copper in it.
Buy Permatex Ultra Copper Maximum Temperature RTV Silicone Gasket Maker (3 oz) 81878 at Advance Auto Parts
You should have a mechanical fit that is very close and be able to seal it from there. I also have been using little welded on tabs that you can pull the slip joints together with a couple of small bolts. I'll try and find a picture.
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Old 03-25-2013, 03:09 AM
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Default rtv red high temp sealer or antiseize

Brent I have used both. You need to be sure that neither one will effect the O2 sensor readings. How much pipe do you have that goes into the header pipes and slides into? Other question is about support of the mufflers and keeping them moving with the motor and not the frame of the car.
I know there is not alot of room, band clamps may also fit and seal.
K&D sell a tail pipe kit with either and expander for inside the tube or reverse cone tool to squeeze the end of the pipe, keep round and take up the room.
I have the origninal pipes and mufflers from ERA of 16 years and have used both antiseize and let the motor warm a idle a couple of times. The other times at the track have been with the RTV orange hi temp. This needs clean areas and a couple of heat cycles to cure. No back pressure on either until heat cycled or you will blow it out. Both are about the same to pull apart if needed. Resize the header tubes and red rtv will work fine.
1 side note, does your motor have a PCV valve? If yes make sure you are not having alot of blow by for this will richen up and cause lean out. Fresh air does the same for the other way. Rick L.
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Old 03-25-2013, 05:20 AM
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I have always used the Copper RTV. I've sealed headers to engines, exhaust manifolds to engines, and downpipes to headers and manifolds with that stuff.
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Old 03-25-2013, 07:35 AM
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If you want to run electronic fuel injection------------its sorta like brakes on a race car----fix the systems/components that are basic to the operation--------in this case, fix the exhaust system---coverups with silicon aren't the answer---------

what tbi system do you have and how about a photo or two of the install?????
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Old 03-25-2013, 05:26 PM
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I bought a exhaust pipe expander and opened the smaller pipe up to fit the outside pipe (larger pipe).


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Old 03-25-2013, 05:53 PM
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ERA recommended Walker Exhaust Sealant which I found at a NAPA. It's suppose to ease dissassembly later also.
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Old 03-25-2013, 07:17 PM
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Quote:
Originally Posted by Dwight View Post
I bought a exhaust pipe expander and opened the smaller pipe up to fit the outside pipe (larger pipe).


Dwight
i was just doing that a few weeks ago. had an expander i bought at harbor freight and because the expander wouldn't go into the pipe far enough it was breaking the flat metal rods, so i had a few more to do so i went and bought another one to finish the deal, and it was breaking also, so i was substituting rods and finally ran out with two pipes to go! i gave up. maybe go down to the exhaust shop someday.
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Old 03-25-2013, 08:13 PM
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I think I paid about $40 for my expander.
Are your pipes steel?
Do you own an oxy/acetylene rig? Apply a lot of heat to them and then use the expander.

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Last edited by Dwight; 03-26-2013 at 06:28 AM.. Reason: sp
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Old 03-26-2013, 05:59 AM
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my expanders were like $15.
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Old 03-26-2013, 06:21 AM
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After owning a backdraft with slip fit headers to side pipes the permanent solution is as follows: Purchase a Lisle exhaust pipe expander about $90.00. You can use a ratchet wrench and it will expand the pipe to the point of tearing with little effort. The little $15.00 pos are good for taking out clamp indentions but not expanding. I broke 3 of them before i got the Lisle and it worked perfect than I sold it as it was still in new condition. Get a piece of exhaust pipe to test fit as you are expanding. After expanding than twist rotate the exhaust on and it will work perfect. For grins use the high temp sealant but the sealant will quickly blow out if the gaps are anything but a crack.
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Old 03-26-2013, 06:56 AM
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the cheap pos would have worked, but the outside cone wasn't in the pipe so the middle portion of the rods were unsupported on the edge of the pipe. i'll look at the lisle, they make some good stuff. i've had the same experience with the rtv, it blows out or sucks in, maybe cause of the too large gap.
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Old 03-26-2013, 07:56 AM
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Update....because of advice above, I went and got a cheapo expander and it worked fine...used copper sealant as well for good measure, but the fit seemed to be snug.

Started up and the same rich condition. Holley thinks it may be because the o2 sensor is only a couple feet from open pipe.

I appreciate the help, guys!
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Old 03-26-2013, 08:07 AM
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i ended up ditching the efi and going to carb, stuck the o2 sensor in a primary pipe for monitor purposes. i asked an efi guru if there should be any compensation on sampling rates for the efi using the primary pipe only and he said no. only thing is you are sampling only one cylinder, so it better be a good one.
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Old 03-26-2013, 08:15 AM
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http://www.spdexhaust.com/pdfs/Temp_Pages/DSMC.pdf

this should explain what you need
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Old 03-26-2013, 02:25 PM
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Quote:
Originally Posted by Jerry Clayton View Post
http://www.spdexhaust.com/pdfs/Temp_Pages/DSMC.pdf

this should explain what you need
Jerry, that's fantastic! Thanks!
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Old 03-29-2013, 03:31 AM
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Hi, unless you want to retain the look of the slip fit , tig welding the collector to the primary pipes , you can have a 4 hole flange in engine bay this makes the corner pipes separate from the headers. Cheers
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