C1 Exhaust Manifold Questions

[Mark P.]

The right side manifold I am planning to install on my 1960 is #3750556 and has some grind marks on it. Any chance these were done at the factory ?

If not, why do you think they were done ?

What is a good way to remove the flange studs ? Even with heat I still broke them.

[William C.]

Re: C1 Exhaust Manifold Questions

Not enough heat or the studs would have come out, next step is drill out and retap. A little inconvenient to ket into the barn right now and look for an early manifold, maybe someone will have on more handy and comment.

[Mark P.]

Re: C1 Exhaust Manifold Questions

Bill - should I gave heated the manifold but not the stud ? Or both ? I did a few minutes with MAPP gas on the manifold around the stud but not directly on the stud. Should I have done like 10 minutes ?

I ended up drilling out and retapping all the threads except a couple were not exactly on center so the rethreading was not very good. I then drilled and tapped for a helicoil which I am sure will hold fine but may cause a bit of a deduction in judging. Hopefully just a point or two.

Any idea if the factory ever ground manifolds ? One of the manifolds on EBAY kind of looks like it was ground in the same place.

Thanks,

Mark

[Mike M.]

Re: C1 Exhaust Manifold Questions

Bill - should I gave heated the manifold but not the stud ? Or both ? I did a few minutes with MAPP gas on the manifold around the stud but not directly on the stud. Should I have done like 10 minutes ?

I ended up drilling out and retapping all the threads except a couple were not exactly on center so the rethreading was not very good. I then drilled and tapped for a helicoil which I am sure will hold fine but may cause a bit of a deduction in judging. Hopefully just a point or two.

Any idea if the factory ever ground manifolds ? One of the manifolds on EBAY kind of looks like it was ground in the same place.

Thanks,

Mark

i believe Bubba did the grinding.mike

[Loren L.]

Re: C1 Exhaust Manifold Questions

If not Bubba, his cousin Floyd.
The one I looked at in the garage (no grind in the area described) had, on the back side and UPSIDE DOWN "A8" (maybe "A6") on the back of the dump and the number "3" forward of the dump......??? Maybe mine was built "from the ground up" by Floyd.........

[Mark P.]

Re: C1 Exhaust Manifold Questions

Thanks for confirming my grinding was not original. I just located another one and will give that a try.

[Gary C.]

Re: C1 Exhaust Manifold Questions

Mark, use Kroil Oil for penetrating oil from www.kanolabs.com Also, have had good success with Freeze Off by CRC available at local auto part stores. Gary....

[Mike M.]

Re: C1 Exhaust Manifold Questions

Thanks for confirming my grinding was not original. I just located another one and will give that a try.

if you've got a good welding shop locally, they can furnace heat the manifold then cast-weld it. then you can take it home and dress it with a grinder then got one of those air tools with multiple needles. that'll restore the sand-cast texture. be sure and give the needles a sharp point and repeat the sharpening of the needles till you've got the sand cast texture on the manifolds repair area. . harbor frieight has the needle air tool. US Navy uses them to chip away paint on their ships. mike

[Mark P.]

C1 Exhaust Manifold Questions - very strange

I just bought another right side manifold for my 1960 and it has been ground exactly like the first manifold. Does anyone have a 1960 manifold without this grinding ? I didn't want to use the first manifold because of the grinding and now I find the 2nd one I bought has the same modification. Seems very unlikely that this could be done so similar if it wasn't at the factory..

[John N.]

Re: C1 Exhaust Manifold Questions - very strange

I just bought another right side manifold for my 1960 and it has been ground exactly like the first manifold. Does anyone have a 1960 manifold without this grinding ? I didn't want to use the first manifold because of the grinding and now I find the 2nd one I bought has the same modification. Seems very unlikely that this could be done so similar if it wasn't at the factory..

Are they repros? I have seen grinding on repros.
Regards

[Mark P.]

Re: C1 Exhaust Manifold Questions

They are both original units cast in late 1959 or early 1960.

[Dick W.]

Re: C1 Exhaust Manifold Questions

if you've got a good welding shop locally, they can furnace heat the manifold then cast-weld it. then you can take it home and dress it with a grinder then got one of those air tools with multiple needles. that'll restore the sand-cast texture. be sure and give the needles a sharp point and repeat the sharpening of the needles till you've got the sand cast texture on the manifolds repair area. . harbor frieight has the needle air tool. US Navy uses them to chip away paint on their ships. mike

Pnuematic needle scaler is the name of the tool you want. Like the Doc prescribed, they will make all evidence of repairs go away on cast

[Mark P.]

Re: C1 Exhaust Manifold Questions

Mike and DIck - thanks for the suggestion. If anyone knows why these might have been ground I would appreciate it. Perhaps it is to clear an alternator bracket or something.

Mark

[Cecil L.]

Re: C1 Exhaust Manifold Questions

Most likely those did not come from a Corvette, but from a passenger car with A/C. Just a W.A.G., but I'm guessing it was done to clearance the compressor front mount.

[Howard M.]

Re: C1 Exhaust Manifold Questions

Mark:
The 0556 manifold on my '60 (I believe it to be original) has the same type of cutout as you describe. However, my looks as if it had been machined for a reason rather than ground out. It has a smooth machined surface which then makes it flush with the end of the cylinder head.