1966-74 BB With Air Conditioning Owners

[Joe L.]

I'd like to have folks with 1966-74 Corvettes with big block and air conditioning check and confirm something for me. It's pretty easy to check; just a glance will do it but a photo would be nice.

What I'd like you to check is the LOWER heater hose nipple. This is the one for 3/4" hose that threads into the WATER PUMP. What I'm interested in is the length. Is it the "long" style nipple (i.e. about 1-1/8" unthreaded length between hex and start of the threads) OR "short" style nipple (essentially no unthreaded length between hex and start of threads)?

[Jim M.]

Re: 1966-74 BB With Air Conditioning Owners

Hi Joe:
I have the "short" style one on my '71 BB air car built 12/29/70.

[Dale C.]

Re: 1966-74 BB With Air Conditioning Owners

Joe

Look at Is '68 25610 out here? 427/390 4 sp. on 25 Oct., George has some good pictures of what he thinks is an origional 68 BB. I talked to him about it and we think it's a non A/C manual car. In the AIM under BB L36 A9, it calls for the production nipple and so going back to the C60 D3 it shows a 3849848 nipple which looks like the one on Georges engine and also 452022 at Corvette Central, as what I put on mine. It's listed in parts catalog under @ 8.866 and for 64 -72 and looks (as in the the AIM, C60 D3) this one nipple was for both small and big blocks. Could you let us know what you find out?

Thanks
Dale Carlson 33147

[Joe L.]

Re: 1966-74 BB With Air Conditioning Owners

Joe

Look at Is '68 25610 out here? 427/390 4 sp. on 25 Oct., George has some good pictures of what he thinks is an origional 68 BB. I talked to him about it and we think it's a non A/C manual car. In the AIM under BB L36 A9, it calls for the production nipple and so going back to the C60 D3 it shows a 3849848 nipple which looks like the one on Georges engine and also 452022 at Corvette Central, as what I put on mine. It's listed in parts catalog under @ 8.866 and for 64 -72 and looks (as in the the AIM, C60 D3) this one nipple was for both small and big blocks. Could you let us know what you find out?

Thanks
Dale Carlson 33147

Dale-----

The 3849848 is correct for non C-60 68-74 big blocks. I'll be posting some information on these after I get a few more "loose ends" tied up.

[Bill C.]

Re: 1966-74 BB With Air Conditioning Owners

72 454 A/C - original nipple and water pump casting.

[Jeff G.]

Re: 1966-74 BB With Air Conditioning Owners

Joe, I responded to a couple of threads earlier this year that are very similar in topic. I posted some pics that you can find there. I have a 69 L36 with AC and original water pump.

https://www.forums.ncrs.org/showthre...70791&uid=7323
https://www.forums.ncrs.org/showthre...70929&uid=8877
Jeff

[Gary C.]

Re: 1966-74 BB With Air Conditioning Owners

Hi Joe

Attached are a few photos. I have two 1967 427/400HP cars with factory A/C, one has AIR as well and is a little hard to get a good photo amongst all the extras. Both have the short nipple.

Regards

Gary

[Dale C.]

Re: 1966-74 BB With Air Conditioning Owners

https://www.forums.ncrs.org/attachme...1&d=1256872960

Joe
I hope this get resized so you can see it. My orginal water pump nipple that came with the 68 BB with A/C some two years had this extended nipple with the large hex stem. As I said, I went with the Corvette Central smaller hex as that was what I thought was called for. Could that larger one be correct?
Dale

[Joe L.]

Re: 1966-74 BB With Air Conditioning Owners

https://www.forums.ncrs.org/attachme...1&d=1256872960

Joe
I hope this get resized so you can see it. My orginal water pump nipple that came with the 68 BB with A/C some two years had this extended nipple with the large hex stem. As I said, I went with the Corvette Central smaller hex as that was what I thought was called for. Could that larger one be correct?
Dale

Dale-----

Let's put it this way: it might be original to the car but it's not the one that was supposed to be installed.

[Joe L.]

Re: 1966-74 BB With Air Conditioning Owners

Thanks to all for the help on this. I was particularly happy to see the 1967 photos that Gary posted. 66-67 is the period I was most uncertain about. However, it looks like at least as far as 1967 is concerned, they were equipped with the nipple that they were supposed to be equipped with. I'll be posting some information on 63-82 heater hose nipples soon.

[Dale C.]

Re: 1966-74 BB With Air Conditioning Owners

Joe
After looking closer at the AIM's for 67 68 & 69 the L36's with air it called for the nipple 3739798 not the 3849848. What's that one? Most of the parts places do show a difference in the non a/c and a/c cars, like Ecklers A9854, that coincidently looks similar to that old one I had on my car with the big hex.
Dale

[Joe L.]

Re: 1966-74 BB With Air Conditioning Owners

Joe
After looking closer at the AIM's for 67 68 & 69 the L36's with air it called for the nipple 3739798 not the 3849848. What's that one? Most of the parts places do show a difference in the non a/c and a/c cars, like Ecklers A9854, that coincidently looks similar to that old one I had on my car with the big hex.
Dale

Dale-----

The GM #3739798 is the short nipple (about 1-3/4" end-to-end length). The GM #3849848 is the long nipple (about 2-7/8" end-to-end length) with the SHORT hex. Both, of course, have hose barbs for 3/4" hose.

[Dale C.]

Re: 1966-74 BB With Air Conditioning Owners

Joe
I am about to redo my hoses and would like to know what H2O pump nipple you ever came up with that would be correct for a 68 BB with A/C (C60)? A picture and ref to Corvette Central ort Paragon would be nice.
Dale

[Joe L.]

Re: 1966-74 BB With Air Conditioning Owners

Joe
I am about to redo my hoses and would like to know what H2O pump nipple you ever came up with that would be correct for a 68 BB with A/C (C60)? A picture and ref to Corvette Central ort Paragon would be nice.
Dale

Dale-----

The fitting you require for the water pump heater hose nipple is the GM #3739798. A photo of an NOS example is attached. However, this is a later version with the "ramped" hose barb. The version in use at the time your car was built used a symmetrical, rounded hose barb. Of course, this feature cannot be seen once the hose is installed.

The configuration of the hose barb was changed via a revision to the specifications for this part in the later 70's.

[Dale C.]

Re: 1966-74 BB With Air Conditioning Owners

Joe
Thanks for the info.
Dale