Drilling Hole in SBC Head for Reverse Cooling

Since you are aiming for the water jacket you can do a small pilot hole with a 1/8" drill bit. That should be easy to control and will allow you insert a piece of wire to feel around with to get an idea of how big the water jacket passage is plus it will allow you to progressively step up in larger bit sizes without going in too deep.

Ideally you should have the head off so you can see though the water passage or go to a junk yard and have a look at a old head and see what amount of casting clearances you have to work with.

More importantly why is your engine running so hot or having circulation problems bad enough that it needs extra coolant passages in the heads in the first place?

More importantly why is your engine running so hot or having circulation problems bad enough that it needs extra coolant passages in the heads in the first place?

No cooling problems. This is a street rod and I'm reverse cooling it and cleaning up the plumbing for appearance and best flow.

It is a "Hot Rod", isn't it?

Sounds like tcmtech has a pretty good idea. Can you inspect another head?

Do you have part nos of heads, what size engine, is that a 302? They sell jigs...You want 3/8ths hole? 4 times, both sides both heads? Is that a T-bucket?

New crate Gen I, 350. Need to tap front of head for 1/2 NPT, so about a 11/16 hole. Pic is a bucket.

I would go with LS eng which comes with rev cooling...but if your heart is set on it, I would certainly find someone who has done this successfully...There is no shortage of hotrodding forums...

http://www.hotrodders.com/forum/reverse-cooling-gen-1-sbc-155657.html

Thanks, Solareagle. I actually posted in the first thread you mentioned, small world. And that book looks very interesting.

Dart, Edelbrock, and any of the aftermarket cylinder head manufacturers that cater to the aftermarket industry should have a template, and detailed instructions for you. Who did you buy the heads from? If they are a manufacturer, or distributer of the heads they should have the answers you need.

New GM crate Gen I motor from Summit.

I'll bet Summit has some information on the project.

SSC pal are these heads the Vortec heads GM is currently using? If so those heads should be around 3-400 thousands thick you should not have a problem drilling those heads for reverse flow, just take your time and use a drill press then follow-up with tap. This is a common procedure on sprint and some drag cars. Drag cars mainly do it to eliminate the water pump out front and to save weight. It works very well on my 410 Yates heads with the Kinsler mechanical fuel injection we had to do it for the place to locate the fuel pump on the cam cover. Duke

Thanks, Lockduke. No, these heads are p/o the GM Gen I motors that they are still making, and wouldn't be the Vortec units.

SSCpal I just thought of something are you blocking the water passages in the intake crossover and tying the rear of the heads into the front fittings or are you planning to flow from the block to the heads at the rear to the front and block the water neck passage. Duke

Here's the motor:

You got it, option #2. There are no water passages in the Potvin manifold and no water neck. Cooled water will flow into the heads first, then down to the block at the rear and forward to exit (reverse flow; rare on street rods, but I have it easy with the AN hoses and like to experiment). Air bleeds at the four top corners of the heads will purge the system. I've done this once before with the U fittings you can see at the front of the manifold. I think the new arrangement will improve flow and purging. Thanks again for your interest and help, Duke!

Front of the head?

reverse cooling goes in the BACK of the heads.

"Reverse" means supplying more (earler) cooling to the BACK of the heads as thats where the heat concentrations are. (farther path for coolant, header heat, transmission heat, firewall heat, no airflow)

Smokey Yunick pioneered this in the 1970s.

Either Circle Track or Stock Car Mag had a write up on it.

Youre inventing a square wheel

Two different versions of reverse cooling. The one the OP is looking to achieve cools the cylinder heads before pushing the coolant into the block, and then to the radiator for transfer to the air stream. Its the same thing, only different.

Exactly right on, Bob. It cools the hottest part of the engine, the chambers and exhaust valve, first. This gives more margin for overheating and detonation, allows more timing, and has other advantages. GM started it with the Gen II LT1 in 1992. You do have to make provision to bleed or vent trapped air and steam.

For safety sake and peace of mind I would put schrader valves in the locations of the water crossovers to vent air locks or steam. you could also use mineral oil instead of coolant to even out the temp and stop steam inside the block but that depends on your location of the country antifreeze may be the only thing you can use. I would also think about using an additive like water wetter to help remove the heat from the engine. It looks like you are going for show. In my case it was function over form and cosmetics did not figure into it. In your case you might use one in the rear and jack the engine up on that side and try and release the trapped air then start the pump or engine to flow the coolant and keep purging until you get all of the air out.Duke

I have a couple of questions.

Do the steam vents get installed on the bottom of the block if south of the equator? And could you use solenoid valves like the nitrous bleed off valves, and double them as windshield washers?

I read an E book that was very thorough on the subject of automotive cooling systems. Tonight I will try to find the name and author and post it. I found a good bit of new information on the subject.

I like the way you think, Bob...warped. I'd like to see that E book.

Right, if the heads are warped sufficiently, the vent passages will not be needed.

Your head is most sufficiently warped.

I had to charge up the battery in the Literati to find that title.

It is "Engine Cooling Systems HP1425, Cooling System Theory, Design and Performance for Drag Racing" by Ray T. Bohach. Kobo wants $16.99 for it.

The purpose of the vents is to let the accumulated air out. That air should only accumulate at the highest point in a cooling system. That should be the thermostat housing, or the branches of the intake leading to it. Will that work?

Not sure what you mean by crossovers...explain?

I did this once before, with the hoses going into the top fronts of the heads (see previous pic). I made custom bleeders for the rear top corners of the heads, with glass reservoirs so I could see the air coming out. I used distilled water and 2 bottles of water wetter in TX. Now that I'm in MN I have to add some antifreeze, or drain the system every winter.

I like to experiment. My car is 20 years old and I've never gone a year without changing something. If you're interested, see tbucketeers.com/threads/big-redo-of-the-old-bucket.13677

the area that is in the intake that crosses over to the opposite head there is one at the front and one in the back. Since you don't have them doesn't mean you cant use those places to put a valve in there. you might locate it in the back of the head so it is out of sight or accentuate it by running separate lines to a viewable reservoir higher up on the intake and make it a subject of conversation for your build and easy to get to. I will check back later got to go on a job now. DUKE

Yep, I'll have 4, one at each corner. Will run tubing from each to a raised tank to burp the system as needed.

Back from work. Have you considered using a mineral oil instead of antifreeze it tends to even out the temp and does a good job of keeping corrosion in the cooling system in check and does not attack the aluminum in the intake. and I do not think it is effected by freezing to the point of expansion in the block. I haven't let mine set outside in the winter here in Indiana I always keep it inside heated garage so I don't drain out the mineral oil. Do you have a expansion tank anywhere in your system to allow you system to compensate for the expansion when hot, and return to system when it cools down to flow back in to the radiator or block.Duke

Take a look at post # 27. The purpose of a cooling system is to transfer heat away from the cylinder head surface. The way to do this is to use the medium that will transfer heat the best, mineral oil is not the fluid to use. I remember water soluble oil from years past, used as a water pump lubricant. I don't know if it is still an option, but think of this. I had an old can of water pump lubricant. It laid around a long time because I favor antifreeze for all. When I finally used it, there was rust inside the can. Not much for inspiring product confidence.

If you are afraid of it freezing up there, ship it down to me for the winter. I promice to never race, abuse, or even drive it hard. Promice.

That is why we went to mineral oil, It was to eliminate the boiling issue, aka no steam and once the system evens out the temp it pretty much stays the same and still below overheat conditions. where we came across using mineral oil was on our our turbo race bike a 6 cylinder Honda CBX the jug assembly was enclosed with alum sheet and drilled thru the fin plates to allow the oil to flow thru it eliminated our overheat problems and at last accounts that engine was still being run that way the same as we had it I am not sure who originally set it up that way but it worked way better than air cooling. Duke.

No argument that mineral oil will transfer heat better than air will. But I believe that water is near the top of the list as far as liquids to transfer heat from the cylinder head surface, to the coolant. It was an entire chapter in the book, but that was two year ago that I read it, and I did not take notes.

I think the main reason we stayed with the mineral oil was that it will not react with aluminum, so no repairs on the alum heads that we spent way too much money on and the Kinsler mechanical fuel injection intake. I thought my house cost a lot of money, but between those two parts I spent way too much money to take a chance on anti freeze or water. Just my take on things, but I do believe you are right about water removing heat better and you can add several different additives to it to increase its ability to take more heat out of the system. If my physical sciences classes in school don't fail this old memory I agree on the article you posted about being correct. we just needed something that would not boil or expand a lot that is why we stayed with it. We are using it in a 410 cu in Windser motor in a 87 T-Bird turbo coupe.it just eliminates all in between rounds work to scurry to change coolant, and you never know how much iron is in the local water at the race tracks in the midwest, causing a lot on iron build up in the engine over time and deteriorating the cooling capacity of the systems. Duke

SEND PICTURES!

Yes, pics please, I need a fix until the next race.

I will try, not very good with camera or getting them to computer will see if my wife can figure out what I am doing wrong