C2 66 427 expansion tank holes

[Terry S.]

We're restoring a 66 427/425 that was in pieces for Flight Judging. This is a December 65 car. On the right front inner fender there are two large holes and one small hole where the expansion tank bracket would normally be riveted on. Since this is a big block and there is no expansion tank, my question is what would these holes be for? The two larger holes had washers on the wheel side and you can see where there is no undercoating under where the washer was. We believe this is an original inner fender not aftermarket. Please see the attached pics. I would appreciate any input.

[John H.]

Re: C2 66 427 expansion tank holes

Terry -

That's an awful lot of undercoating coverage. The original inner fender came from the molding source with all four holes for the expansion tank bracket pre-drilled, and both plants filled the four holes with bond material on big-block cars.

I can't think of anything the plant would install in that area that required two holes and flat washers; are there two more holes there that are covered by the undercoating?

[Jeff D.]

Re: C2 66 427 expansion tank holes

My 66 425 HP car also has the holes for the tank in the RT inner fender. I talked with an NCRS judge and he told me all 66's big or small block had the holes for the tank. He has seen some original big block cars that even had the bracket riveted in place but not used. Maybe it had one and someone removed it? Just a guess. I was told to leave the holes alone and not fill them as they are original. Hope this helps. Jeff

[Marco H.]

Re: C2 66 427 expansion tank holes

Jeff,
What month was your car built?? A.O.Smith or St.L.?? As far as I can remember reading a NCRS Restorer Article, the early A.O. Smith bodies had the bracket installed (built as per 1965 specs). Upon car assembly at St. Louis the brackets were removed and left a bare spot (no black-out paint)
on the fenderwell.
Marco

[John H.]

Re: C2 66 427 expansion tank holes

Jeff,
What month was your car built?? A.O.Smith or St.L.?? As far as I can remember reading a NCRS Restorer Article, the early A.O. Smith bodies had the bracket installed (built as per 1965 specs). Upon car assembly at St. Louis the brackets were removed and left a bare spot (no black-out paint)
on the fenderwell.
Marco

Marco -

Do you recall the "Restorer" issue that article was in? I have the "everything" Restorer CD and I'd like to read it.

[R N.]

Re: C2 66 427 expansion tank holes

John ---

I had always thought that the BB cars had "dimples" on the inner fenders rather than drilled holes.

[John H.]

Re: C2 66 427 expansion tank holes

John ---

I had always thought that the BB cars had "dimples" on the inner fenders rather than drilled holes.

Kurt -

Nope - the holes were pre-drilled in the panel by the molding source. If there were dimples for them, drilling the holes and the hole diameters would be called out in the Assembly Manual on the sheet that shows riveting the bracket to the inner fender.

The Chevrolet Assembly Manual doesn't show filling the holes with bond (one of many process details left out of the A.I.M.), but the highly-detailed A.O. Smith process sheets (500 pages) have a sheet that specifically shows filling the holes with bond, only on big-block cars (except L-88).

[Marco H.]

Re: C2 66 427 expansion tank holes

John,
It is in the Spring 2003 issue. "A Study of the 450HP L72" by Everett Ogilvie.
Marco

[Marco H.]

Re: C2 66 427 expansion tank holes

Kurt,
Look for a Thread "67 427 Speedo Cable Routing" a few days back. In there you will find a picture of an original, unrestored 427 Battery area. It shows nicely the factory filled holes in the fenderwell.
Marco

[R N.]

Re: C2 66 427 expansion tank holes

Thanks John. My '66 is an AOS car and I've never really looked that close as I had always thought of them as dimples. You learn something new here every day!

Kurt -

Nope - the holes were pre-drilled in the panel by the molding source. If there were dimples for them, drilling the holes and the hole diameters would be called out in the Assembly Manual on the sheet that shows riveting the bracket to the inner fender.

The Chevrolet Assembly Manual doesn't show filling the holes with bond (one of many process details left out of the A.I.M.), but the highly-detailed A.O. Smith process sheets (500 pages) have a sheet that specifically shows filling the holes with bond, only on big-block cars (except L-88).

[Terry S.]

Re: C2 66 427 expansion tank holes

Terry -

That's an awful lot of undercoating coverage. The original inner fender came from the molding source with all four holes for the expansion tank bracket pre-drilled, and both plants filled the four holes with bond material on big-block cars.

I can't think of anything the plant would install in that area that required two holes and flat washers; are there two more holes there that are covered by the undercoating?

Thanks John,

No, there are just the two holes and they are a approx. 1/2" in diameter each.

[John H.]

Re: C2 66 427 expansion tank holes

John,
It is in the Spring 2003 issue. "A Study of the 450HP L72" by Everett Ogilvie.
Marco

Thanks! I'll take a look at it.

[Wayne W.]

Re: C2 66 427 expansion tank holes

Former owner inspired.