[Bill Hanlon]

Tried "search" and couldn't find what I was looking for. A guy over on the Old GMC forum has a '56 GMC with a stock Pontiac V8. He needs a set of water distribution tubes for his heads. 55/56 tubes are part number # 518063 both sides. 57/58 is 523327. I don't know if the later tube will go into the earlier head. I think the early ones were some kind of copper/brass alloy, while the later ones were stainless.

I have ONE spare '58 tube that I'm willing to donate to his cause.

Anyone know for sure if the later tubes will or will not go into the early heads?

[Safari Larry]

The switch from brass to stainless was made December 1955 so early 56 tubes were brass. I have a set of 56 heads with the stainless tubes but can't get them out. I'll diddle with it some more today and see if I can make any progress. I doubt the 57-59 tubes will fit in the 55-56 heads but I don't know that for certain. I will check if I can get the tubes out of the 56 heads.

[Bill Hanlon]

So you have a 57-59 tube Larry?

[Safari Larry]

Yes I do.

[CATBIRD]

I seem to recall that there is a difference between left hand and right hand tubes 1957-59. They do have different part numbers don't they? Before these tubes get buried in someones heads, has anyone thought about trying to have them reproduced? Their not often needed, but when they are, they can't be found……John

[Safari Larry]

Yes, 1957-59 have left and right tubes with different part numbers. 1955-56 tubes are same on both sides, one part number.

[Bill Hanlon]

Larry's Pontiac MPC lists 57-59 tubes 523327 in the right head and 523328 in the left head. The GMC Master Parts Book states 523327 for both tubes. Wouldn't be the first time the GMC book was wrong, but ......
The heads are interchangable side to side. Does that mean the tubes are not?

[Safari Larry]

Pontiac heads are interchangeable side to side but 1957-59 tubes are not. Looking at the tubes from the end, they are mirror images of each other (see attachments). The tube can be inserted in the head only from one end and the flared end needs to be in the front. If you moved a left head with left tube to the right side then the flare would be at the back of head which would be incorrect.

The 1955-56 tube can be inserted in either end of the head. If you moved a left head to the right side then you would need to remove the tube and insert it from the other direction -- so the flare is in front.

I'll take a look at my 56 heads today, didn't get a chance to yesterday, sometimes life gets in the way of important stuff.

[Safari Larry]

I diddled with the 56 heads yesterday and got one of the tubes out without bending it up too badly. Can't get the the other out, it is stuck.

I tried a 57 tube in the 56 head, it would go part way in but a rib near the center of head stopped it from going in further. It was same inserting it from either end. It might be rust buildup in the center two ribs that prevented it from going all the way in, not sure about that. Those inner ribs are difficult go get to.

Some photos attached of tube in 56 head and 56/57 tubes together for comparison (57 is cleaner).

Bill, I think your GMC parts book is incorrect.

[Bill Hanlon]

Originally Posted by Safari Larry

Bill, I think your GMC parts book is incorrect.

I agree. Thanks for looking.

[Teej]

How would you go about getting these out?

[Safari Larry]

Originally Posted by Teej

How would you go about getting these out?

Sometimes you don't get them out without destroying them. The one I had difficulty with, I "pushed" it out part way from the back end with a sawed off broomstick and a hammer. Then I pulled it out with pliers from the front end. This caused some damage to both ends of the tube but not severe. The other 56 head I have, I cannot get the tube out without destroying it. So the tube stays and I still have a useable head.

The tubes came out of my 57 heads without much problem. I think it depends on how much rust buildup is in the head. It might help to "tank" the heads first.

Such issues may be in part the reason Pontiac abandoned reverse flow.

[55GMCX2]

Larry,

I'm the guy that Bill has been helping out with the tubes. Thanks for taking the time to test fit the 57 tube in the 56 head. So far, I've only been able locate a set of tubes from a 58 engine. Too bad these won't fit my 55 heads.

Does anyone know if these are being reproduced? I talked to California Pontiac Restorations yesterday and they used to stock these, but they are now discontinued.

Thanks,
Steve

[Bill Hanlon]

Steve:
You might try http://www.indianapontiacs.com/Partscars.html
They list a '55 and a pair of '56 Pontiacs that they are parting out.

[Safari Larry]

Originally Posted by 55GMCX2

Larry,

I'm the guy that Bill has been helping out with the tubes. Thanks for taking the time to test fit the 57 tube in the 56 head. So far, I've only been able locate a set of tubes from a 58 engine. Too bad these won't fit my 55 heads.

Glad to help Steve, we are fortunate to have Bill's help, he's been of considerable help to me also.

I think the 57/58 tubes will fit into the 56 heads with just a little work. The 57 tubes can be inserted in the 56 heads down to near the center exhaust port from either end. Looking though the head cavity where tubes are inserted, it looks like it is the same profile all the way through. Knocking out the rust down towards the center of the head cavity MIGHT allow the tube to go all the way through. If it doesn't then a little grinding would likely create the necessary clearance. Trouble is, grinding out metal way down in those cavities might be a bit difficult.

Now the question is "are the 56 heads same as 55?" 56 heads have slightly larger exhaust ports and different rocker studs but but I suspect 55/56 are the same where the tubes are inserted, they use the same tubes.

So if you have access to 58 tubes and can't find 55/56 tubes, I suggest trying them with the understanding that you can return them if they can't be made to fit. Even if you get "stuck" with the 58 tubes and can't use them, you will have something valuable for others and probably quite desirable on ebay.

Question??? What happened to your original tubes? Were they in bad condition when the heads were removed?

[Safari Larry]

Good news, I used a long round file to knock out some of the rust buildup from inner 56 head and the 57 tube now inserts freely into the head! Assuming the 55 head is the same as 56, the 58 tubes will work.

The tube will insert into the head from either direction which surprised me. So that leaves the question "which way should it be inserted?" Remember for 1957-59 there is a left and a right tube. It fits better in one direction (flatter side towards exhaust) than the other so that's the way I would install it. It looks like it would work about the same installed from either direction so it may not matter.

I cleaned up my 56 tube and it is brass. That agrees with head casting date, J225 = Oct 22, 1955. Photos attached of the 56 brass tube and 57 stainless tube.

[Bill Hanlon]

Originally Posted by Safari Larry

"which way should it be inserted?"

If one end is "belled" like the '58 tube is, I would guess that is the forward end.

[Safari Larry]

Originally Posted by Bill Hanlon

If one end is "belled" like the '58 tube is, I would guess that is the forward end.

Correct that is the forward end but what we don't know if it the left or right side? There is a left tube and a right tube for 1957-59.

[55GMCX2]

Originally Posted by Safari Larry

Good news, I used a long round file to knock out some of the rust buildup from inner 56 head and the 57 tube now inserts freely into the head! Assuming the 55 head is the same as 56, the 58 tubes will work.

That is good news. Thanks for taking the extra time to clean things up so the tube would fit. The pictures also help!!

I've contacted IndianPontiacs as Bill recommended to see if they have a set of 55-56 tubes, but I'm still waiting to hear back from them. I may go ahead and get the 58 tubes just to try them, but like you said, the challenge is going to be, which is left and which is right. I'd also like to see the two side by side for comparison.

The machine shop that's rebuilding my engine said that the tubes I have are shot and need to be replaced. They said that I could probably get away without them, but if I can find a set, then I'd be better off with them than without.

Thanks again,
Steve

[Safari Larry]

Originally Posted by 55GMCX2

I'd also like to see the two side by side for comparison.

See my 03-03-2013 post for left and right 57 tubes side by side. Looking at the end, they are mirror images of each other. It is most obvious in the back end view of the tubes. I really don't think you can go wrong, if they are installed on the "wrong" side, I believe there will be little or no difference in effectiveness. The water exit ports will be on the bottom either way. There is one way of installing them where they appear to be a better fit and that's how I would install them -- and not worry about it being wrong.

Originally Posted by 55GMCX2

They said that I could probably get away without them, ...

I think that is bad advise. Yes, you can get away without them for a while. But the back of engine will run hotter than the front and it won't show up on the temp gauge. Not good for a long lasting engine! I would not use those heads without the water tubes.