Crossmember Under Radiator Rust Out Problem
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,265
Likes: 547
Crossmember Under Radiator Rust Out Problem
Has anyone used a #203015 corvette cental part on their 69-72 and how was the fit? I tried to post a link off their picture properties and it linked to the wrong pic.Thanks. Ron B
Instructor
Joined: Feb 2007
Posts: 114
Likes: 18
From: McKinney TX
This extract from a Vette Magazine article (Big Block from Hell) in the 90's may be helpful.
Much Ado about Core Supports
There were four core supports used from ’69-’72. To differentiate, measure across the radiator opening:
1) 19" hole p/n 3966591–low-performance, small-block, manual, no air
2) 21" hole p/n 3966597–all w. L88, ZL1, early ZR1, ZR2.
3) 26" hole p/n 3966594– small-block, air
–hi-po, small block, M20/M21 manual, no air
–small-block, automatic
4) 27.5" hole p/n 3966596– big-block, M20/M21 manual, auto
All of these are discontinued Chevrolet parts, however, a derivative of #4 (p/n 339176, introduced for model year 1973) was available. If you use it on a ’69-’72, you accept any cosmetic differences and drill two 1/4" holes to mount the fan shroud.
First, we hunted for a serviceable used core support. None was found. We looked at repairing the existing piece by removing rusted sections and welding in new material. Not. A better idea was a reproduction. Numbers 2-4 can be had from Eckler’s. As the Big-Block from Hell is a ’71 coupe; we ordered p/n 25155 which replaces Chevrolet’s 3966596. It’s identical to the original part and bolted in with no problems.
Much Ado about Core Supports
There were four core supports used from ’69-’72. To differentiate, measure across the radiator opening:
1) 19" hole p/n 3966591–low-performance, small-block, manual, no air
2) 21" hole p/n 3966597–all w. L88, ZL1, early ZR1, ZR2.
3) 26" hole p/n 3966594– small-block, air
–hi-po, small block, M20/M21 manual, no air
–small-block, automatic
4) 27.5" hole p/n 3966596– big-block, M20/M21 manual, auto
All of these are discontinued Chevrolet parts, however, a derivative of #4 (p/n 339176, introduced for model year 1973) was available. If you use it on a ’69-’72, you accept any cosmetic differences and drill two 1/4" holes to mount the fan shroud.
First, we hunted for a serviceable used core support. None was found. We looked at repairing the existing piece by removing rusted sections and welding in new material. Not. A better idea was a reproduction. Numbers 2-4 can be had from Eckler’s. As the Big-Block from Hell is a ’71 coupe; we ordered p/n 25155 which replaces Chevrolet’s 3966596. It’s identical to the original part and bolted in with no problems.
Thread Starter
Melting Slicks
Joined: Jun 2001
Posts: 2,265
Likes: 547
Thanks Gearhead, I don't know how many times I've read the BBH articles, But Batman is right, I am wondering about the crossmember beaneath it, they can look good and be paper thin from internal corrosion. Mine has pinholes and I'd rather replace it, both corvette central, and ecklers have them. I just have heard horror stories about reproduction part fit. Ron B.
Le Mans Master
Joined: Mar 2001
Posts: 6,240
Likes: 1,013
From: Watkinsville, GA and Glen Cove, NY
You can easily take the crossmember off and have new metal welded in. It is usually in the corners where this bumper crossmember rusts out. Mine is rusty too and this is on the to do list.
Bill
Bill
Former Vendor
Joined: Oct 2007
Posts: 2,092
Likes: 2
From: walpole ma
cross member.
I have done both(repaired some and used a new repro one.) For the roughly 200 dollars that a new one costs it is a good deal and fits well.
You can repair yours if you want but depending on how bad it is it may not be worth it. Plus ,you may repair a bad spot ,and somewhere else where the metal is thin from the inside but you just cant see it yet,can rust later on.
The new one is the safe bet.
You can repair yours if you want but depending on how bad it is it may not be worth it. Plus ,you may repair a bad spot ,and somewhere else where the metal is thin from the inside but you just cant see it yet,can rust later on.
The new one is the safe bet.
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Brett Foote
Le Mans Master
Joined: May 2006
Posts: 5,814
Likes: 414
From: Pittsburgh suburbs Pa.
Mine was rusted in the corners on my 68. I cut out the rust and made metal pieces that fit flush and welded them in, ground the welds flush and painted it. You can't tell it from new. Took a couple hours to do the metal repairs. A lot cheaper than buying new. 
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
EH, been 12 years now, I bought used for my '72 here, and it's still fine...course I cheated....drilled drain holes in the lo spots for the water that will for sure get in there to sit, NOT NOW.....
and also poured in a whole can of naval jelly....let it drip dry itself out....
12 years later, still good....
and also poured in a whole can of naval jelly....let it drip dry itself out....
12 years later, still good....
Burning Brakes
Joined: Oct 2001
Posts: 911
Likes: 5
From: TN
Team Owner
Joined: Oct 2004
Posts: 23,831
Likes: 10
From: Springfield MO
St. Jude Donor '07
EH, been 12 years now, I bought used for my '72 here, and it's still fine...course I cheated....drilled drain holes in the lo spots for the water that will for sure get in there to sit, NOT NOW.....
and also poured in a whole can of naval jelly....let it drip dry itself out....
12 years later, still good....
and also poured in a whole can of naval jelly....let it drip dry itself out....
12 years later, still good....
