1957 347 rebuild

[mdbomstad]

I am rebuilding a 347 for my GMC the block and crank are at the machine shop and all looks good so far. I have been studying the heads and understand the copper tubes that direct the water blast will not survive the hot tank. Does anyone know the procedure to remove them without damage? does anyone know where to get replacements if necessary? Is it necessary to install guides and hardened seats in the reverse flow heads? Any insight will be appreciated.

Mike B.

[Larry]

I have checked a couple of old manuals and when they address the water distribution tubes, they simple say "remove" when doing a valve job. If yours are anything like in the older flatheads that I have rebuilt, they just pull out. Now, if they are corroded they may be a bit stubborn. At least yours are copper, so there is some hope for them. many were just sheet steal and they were always rotted beyond hope.

I see that CPR in California lists them. They give our members a 10% discount, so mention PontiacRegistry.com. Also Then and Now in Mass. might have the tubes. They also give our members a 10% discount.

Northwest Auto in Grand Rapids, MI may have the tubes too. They have tons of old engine parts. They aren't passing on discounts, but have always =been reasonable.

Don't forget to check a place like NAPA too. You might have to sweet talk an older guy to dig out some books 'cause I doubt it would be in their computers.

As for valve guides, standard one should be fine, and most everyone has dropped off of the hardened valve seat (panic) bandwagon. It was a big fluke. Unless you're gonna pull a horse trailer full of hay burners cross country at 70mph all day, you will never have any "valve seat regression" issues.

If the valve guides are close to tolerances, a simple knurling is a good idea. It "fattens" everything and allows for a little extra lubrication.

[mdbomstad]

Thank you Larry, I did contact both places you mentioned but they no longer have them. The folks at CPR did say that the distribution tubes are vital to the proper cooling of the head. The tubes in 55&56 were different, 57&58 were copper and the tube for 59 was galvanized. They suggest to have them fabricated. I have done sheet metal work so I may get some sheet copper and see what I can make.

Mike B.

[Larry]

Not surprised to hear they are not available. Probably a limited supply of such specific items ere ever made in the first place.

Save your patterns if you succeed in making your own. I'll bet there are others who need them too. They aren't too complicated, but still above the average bear's ability.

Let us know what happens.