JRHaelig

How Far Can You Shave A Manifold

Recommended Posts

I've been messing with old cars long enough to know that things are rarely as bad as they seem.   They're usually worse.

 

I've had an exhaust leak at the last cylinder since I got the car started.  Not the end of the world, but let's put a new gasket in and fix it.

 

Well, my old pal "root cause" showed up.  Some how the end of the manifold is way off - like a pregnant 1/16".  Little wonder that the gasket gave up.

 

That last manifold bolt hole had wallowed out, so I re-tapped it at 7/16ths, and now I see this!

 

So - can the manifold set be dressed enough to fix this or do I just put it back together and wait for the new copper gasket to blow out?

 

buick manifold gap.jpg

Share this post


Link to post
Share on other sites

Or, perhaps  :  Given that the rest of the manifold is co-planar at all holes, and the fact that the last hole is plane-parallel (little  or no wedge to the gap), couldn't  you simply shim/discretely gasket the end hole ? This would equalize the slack, and might permanently solve the recurrent problem. I have never done this, nor have had need to. But like (almost) all of us, have had, and am very annoyed by exhaust leaks. But unlike so many of you guys and gals, I, sadly, fall in to the lazy end of the effort spectrum. I wonder if anyone has tried this ?    -   Carl 

  • Like 1

Share this post


Link to post
Share on other sites

I was thinking about that, too.  Add 1 section of the old gasket on that port, but wouldn't it blow out, or do you think the compression from the torqued manifold would keep it intact?

Share this post


Link to post
Share on other sites

I think the amount of, the thickness of the "shim" (and perhaps the material), is critical. If it is just a few thou' thicker than the offending gap, my guess is that you would have a cure. It would be a good idea to increase exposure by posting above in General, or Technical. Since this is not a Buick specific problem, and since this shim idea occurred to both of us, certainly someone has tried it.   -   Carl 

Share this post


Link to post
Share on other sites

Basically, shim it to the gap size then add gasket? You need crush on the gasket to seal. But would the shim seal? Maybe not... so how much does the gasket crush from its starting thickness? So maybe you need to use gasket as shims so the same amount of crush occurs in each gasket?

 

We are assuming all the other faces are co-planar and adjusting the fit between the two manifolds won't help.

Edited by Spinneyhill (see edit history)

Share this post


Link to post
Share on other sites
3 hours ago, JRHaelig said:

Will REMFLEX take up that much slack?

 

From the company website:

 

Remflex Performance Promise

• Seals Warped Flanges:

Remflex exhaust gaskets come in a standard 1/8-inch thickness and are designed to crush 50%. This allows them to fill gaps in the flange surface up to 1/16-inch! 

• Won’t Burn Out:

100% flexible graphite construction means Remflex gaskets are good for up to 3,000 degrees F—far exceeding that of any vehicle’s exhaust system temperature! 

• No Re-Torquing Necessary:

Remflex exhaust gaskets rebound 30%, creating an optimum seal that eliminates the need to re-torque!

 

About Remflex

Remflex’s unique flexible graphite material has been proven for more than 30 years in industrial applications, where temperatures routinely exceed 2,000 degrees—day after day, week after week, year after year. Now, we’re bringing this technology to enthusiasts of all kinds to eliminate exhaust leaks for good! Whether you have an old pick-up that needs a manifold gasket, or a race car with custom-built headers, you can be assured that Remflex exhaust gaskets will work properly the first time, every time.

  • Like 1

Share this post


Link to post
Share on other sites
8 hours ago, C Carl said:

Or, perhaps  :  Given that the rest of the manifold is co-planar at all holes, and the fact that the last hole is plane-parallel (little  or no wedge to the gap), couldn't  you simply shim/discretely gasket the end hole ? This would equalize the slack, and might permanently solve the recurrent problem.

 

That sounds like what I would do. And extra layer of gasket material at that last port. Could make it out of sheet copper with a circle cutting tool, and tin snips, just a drill, and hand tools. I have made gaskets that way. Either a hole saw or one of these -

MIBRO Adjustable Circle Hole Cutter For Wood, Plastic and Composites

 

Share this post


Link to post
Share on other sites

I had the same Problem , 

Original, there is no gasket,the intake have the rings inside and the Exhaust had a graphite grease between Head and EM to let them moving because of the heat expansion in lengths.

Don't try to pull a bended Cast Manifold down tight with the bolts..,a cracket EM can be the result .

 

If it's only the rear runner  thats not match with the Intake ? If yes,than bring it to a Maschineshop for that they planning the complete Intake/Exhaust combo down to a matching surface..,I had do that too.

Then it's no problem to use the copper gaskets ( Best Gasket offer its too)

If all EM surfaces don't match with the IM ,then I would align intake to exhaust  first.

 

 

20181025_153752.jpg

  • Thanks 1

Share this post


Link to post
Share on other sites

Thats what I would do, too. Align the manifolds to each other in such a way to minimize the error, and then have it machined.

Share this post


Link to post
Share on other sites
4 hours ago, Bloo said:

Thats what I would do, too. Align the manifolds to each other in such a way to minimize the error, and then have it machined.

Caveat to folks doing machining to staighten alignment of sufaces! CAREFULLY MEASURE THE INTAKE RINGS TO MAKE SURE THEY DONT END UP TOO TALL FOR GROOVES THEY SIT IN AFTER MACHINING! Just a reninder.

  • Like 2

Share this post


Link to post
Share on other sites
16 hours ago, 2carb40 said:

What function did the engineering staff have in mind for the inserts originally? Alignment, vacuum?

Yes, l think so too, allignment and also sealing.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...