1968 SB radiator replacement

[Richard D.]

The incorrect copper/brass rad. in my car is going to be replaced with a new Dewitts one this weekend. Engine is the L-79 with remote fill tank.

The current copper/brass (AutoZone replacement?) has 2 bolts into the bottom of the radiator (where the the 2 rubber cushion mounts are), and I noticed on the DeWitts that the 2 guide tubes that the rubber mounts go over are not threaded for bolts.

Are bolts used at all to secure the bottom of the radiator to the mount, or does it just sit in the mounts, and the securement of the radiator is accomplished by the top bracket?

Also, is there any other cushion pad under the radiator besides the 2 rubber mounts? I have purchased the mounting sealing foam kit from the Dr., but none of the pieces seem to be a pad for the bottom.

Thanks in advance for any help.

Rich

[John H.]

Re: 1968 SB radiator replacement

Rich -

Nope, no bolts - just the pins and round cushions; retention is at the top.

[Richard D.]

Re: 1968 SB radiator replacement

Thanks John.

Would you know about the other part of my question concerning any other support for the bottom besides the 2 cushions, like a foam strip?

Thanks again for the info.

Rich

[Kurt B.]

Re: 1968 SB radiator replacement

I just did the same procedure on my 68 L79 and there are no other "cushions" on the bottom other than the 2 (one in each side) in each of the brackets that support the radiator. There is a foam rubber "seal" that keeps out dirt on the bottom but it is not a cushion and serves no support function. I also obtained mine from Dr. Rebuild and everything fit perfect. The DeWitt radiator was perfect and worth every cent.
You mentioned a remote expansion tank: I assume you do not have A/C as I do not have such a tank. I have A/C and am second owner since 1972 and see no place where a tank may have previously been located or subsequently removed prior to my purchase. My build date is May 10, 1968.
Kurt Bunting

[Joe L.]

Re: 1968 SB radiator replacement

Kurt and Rich-----

Now, this is a little confusing to me.

First of all, the 63-72 small block aluminum radiator, GM #3155316, used only the 2 dowel-like "pins" at the bottom. These fit into round rubber cushions and thence into the radiator support cup-like brackets welded to the bottom member of the radiator support. This same, basic lower mounting was used for all 63-72 small block which used the aluminum radiator even though the radiator supports otherwise changed configuration over the years. In fact, the exact same mounting was used for the HD aluminum radiators used for 1965 L-78, 1967-69 L-88/ZL-1, and 1970-72 ZR1/ZR2. ALL of these radiators used an external supply tank.

Original 1968 L-79 applications with C-60 did not use an external supply tank. That's because they didn't use an aluminum radiator. They used a copper/brass radiator of GM #3008567 which had integral tanks and a filler on the right side tank. These radiators also did not use the "pin" style lower mounting. Instead, they used the "stirrup-type", u-bracket mounting, both upper and lower. The lower brackets are welded to the support and have a long, thin rubber cushion which isolates the radiator from the bracket. The upper brackets are nearly identical but are attached by bolts to the support.

So, it sounds like you are talking about the lower mounts used for the aluminum radiator, but then you say that you have a C-60 application (that for 1968 didn't use an aluminum radiator). That's what confuses me.

[Kurt B.]

Re: 1968 SB radiator replacement

Joe,
My mistake. I did not mean to imply that I have an aluminum radiator. I do indeed have the copper radiator with the side fill and the stirrups on the bottom. I must have misread Rich's post as I assumed he was installing this same type of radiator. I think that the radiator used with the C 60 Air Conditioning isa very similar in appearance to the radiator used for big blocks. In any event, I have the copper radiator as you described. Sorry for the confusion. I am glad to learn that my car never came with the fill tank and that I am not missing anything. Incidentally, the body shop called and said that my car should be returned with nice new LeMans blue paint in the next two weeks. I can't wait as this resto has been 8 long years in the making.
Kurt

[Justin N.]

MMMMmmm....Lemans Blue 68....

...like my neighbor's 327/350hp

Justin

[Richard D.]

Re: 1968 SB radiator replacement

Hey Guys -

My 68 did not have A/C, therefore, the Alumiminum Rad. with external supply/fill tank.

Going back to my original post, I found out there's no bolts that that go into the bottom "dowels" or posts, that are now there into a non correct brass/copper replacement Rad. now in place (thanks John and Tom).

The rubber grommets that go over the posts are there, and in good condition, so I will place them over the posts and install the Rad. tomorrow.

The foam air dam kit I got from the Dr. looks like it will work out just fine.

Thanks Guys,

Rich

[Joe L.]

Re: 1968 SB radiator replacement

Rich-----

Not only weren't there ever any bolts into the lower dowel pins, you absolutely don't want any bolts there when you're using the aluminum radiator. The whole mounting system for the aluminum radiators was designed to isolate the aluminum radiator from any contact with dis-similar metals. That's the purpose for the rubber cushions on the bottom dowel pins and the u-shaped, central upper mount cushion.

The bolts on the bottom dowels wouldn't create as much of a problem with the copper/brass replacement radiator you had, but they're totally unnecessary. The same mounting system originally used will work for the copper/brass replacement,too.

[Joe L.]

Re: 1968 SB radiator replacement

Kurt-----

Not only is the 1968 L-79 with C-60 radiator very similar in appearance to the big block radiator, it's the exact same radiator as originally used for all 1968 big blocks with 4 speed (except L-88). During the 1965-72 period there was only 1 year in which the big block and small block radiators were the same for certain applications. That year was 1968. All 1968 small blocks with THM-400 and/or C-60 used the same radiators as big blocks.

The only other really small exception was 1971 ZR-1 and ZR-2. For these options, the HD aluminum radiator was used for all. In fact, the 1970-72 ZR-1 was the only small block application EVER for the HD aluminum radiator, GM #3007436.

For 1973-74 small block and big block radiators were the same.

[Richard D.]

Re: 1968 SB radiator replacement

Thanks Joe.

Galvanic reaction of 2 disimilar metals I believe.

Rich