Can't find much info on this. I've got a pair of 347 heads being redone right now. The copper water diffusers (or restrictors, or whatever you call them) that are in both of the water inlets on the heads are deteriorated and falling apart. I assume they are necessary to slow the flow of the water down - but I have no idea where to find another set - or is it better just to fab up some sort of a smaller-hole restrictor to put in each one? Run without them? Any advice is appreciated.
Are you talking about these? Discontinued but they were a bargain in 74! These guys will know what you are talking about. California Pontiac Restoration 820 Poinsettia Santa Ana, CA 92701 Ph: 714-245-9800 Toll Free: 1-877-504-8124 Fax: 714-245-9269 cpr@dcninternet.net
With some dimensions and some copper pipe it looks like a fairly easy fab job. A minor flare at the end, a hammer and a length of hardwood, the right size drill bits, voila... Awright, a quick edit: Thinking Packard and a similar part in the later 8cyl models, they were brass diffusers. Are we certain that yours were copper? Brass pipe is still used for plumbing needs but you might have to anneal it 1st, which also isn't rocket science. Just offering help, but I was having memories of some Pontiac escapades from my youth based on the title. Just sayin...
These looked copper. They wouldn't pull out, and when they went to the hot tank, they were so bad they just fell apart the guy said. So at this point, I have nothing to go by. I emailed CPR to see - they may have them. They apparently are diffusers that direct the coolant right at the exhaust valve seat. Now, whether they are 100% necessary I don't know...I don't know much about reverse-cooled engines.
Crap. CPR doesn't have them. Early Pontiac guys - are these 100% necessary for me to have? I can't find squat online about them.
If you find a set of 58 or 59 heads, the tubes were made out of stainless steel and usually will come out with out too much trouble. I never had any success in getting out the older brass ones.
I guess I'm puzzled as to why these are so crucial. The head is getting water first regardless of whether the tubes are in are not, they just jet-direct the water right to those specific areas, but every other head on the planet that's not reverse cooled gets water AFTER its been through the block anyways. Pontiac didn't change much of anything on the head geometry through the years, and you can even use the early heads on later stuff by putting a freeze plug in the front anyways....so I guess I'm puzzled as to why these are necessary.
I have no hands on experience with them at all. But if Pontiac engineers thought they needed them I'm quite sure there is a very specific reason. The cool water enters the head evenly, without the tube the front end/cylinder gets all the cold water and gradually warms to hot by the back. Pontiac didnt run reverse cooling for very long- either there wasn't enough performance return for the effort or it was too expensive or it didnt work. If you are going with reverse cooling I'd run them, if you are going bottom up cooling i can't see why you would need them.
Was an idea ahead of it's time. The early ones had a high failure rate. Since the blocks, heads, water pump, and timing cover were made for this not sure about making that change. Maybe someone else has done it?
They were using these back on the flathead engines also, some reason they thought they needed to carry the design over the the new v-8 at the time (287) when it came out.
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