drilling holes in SBC cast iron heads

I want to drill and tap holes in the front of my heads for cooling, like this:


What's the best way to do this? How thick is the head wall at this point? How close is the cylinder? Any gotchas?

 

I can't see where you would gain anything by doing that as that appears to be a cutsie show car that probably never sees serious street driving. From looking at the size of their braided hose it's pretty small and restrictive.

 

Looks like trouble to me.

 

Where does the thermostat go?

If you are serious about this ... pick up a used, junk head and drill it ...

 

I already use #10 hoses in my cooling system, on a blown SBC, with an electric water pump, electric fans and no thermostat. Cools fine. This mod is to reverse flow the system and clean up the plumbing for appearance and best flow.

 

If you want to drill and tap for effective cooling then drill into the back of the intake manifold - near the distributor, both sides and return from there. That way water will flow thru the motor and across the heads then to the radiator.
If you look how the water flows in a chevy it goes into the front of the block and then straight up to the crossover for the thermostat housing and into the radiator. The lions share of cooling is done by convection because water don't flow to the back of the block or heads, there may be some little water flow but it is minimal. Once water gets saturated with heat it telegraphs the heat instantly to the front of the engine and gets absorbed by the water flowing to the thermostat.
Lots of race engine feed the water into the back of the cylinder heads and return it from the front of the block (reverse cooling) and will have an extra return from the middle of the cylinder head - there's water ports cast into the heads to return from.

 

Can this be done ,my idea is to machine front of heads and use a 32style rad with 2 hoses just like a flathead and put thermostats in hose,reason is to us a old blower manifold ,might be extra work but will it cool with a good fan and shroud and water pump?

 

http://www.speedwaymotors.com/Speedway-Small-Block-Chevy-Cooling-Unit,1856.html

 

If you are worried about having enough depth to completely tap the hole, mount your fitting to a bolt on plate, machine a flst area on the front of the head and bolt on the plate. takes less depth to correctly tap two 3/8-18 holes then a pipe tap.

 

That doesn't do what he wants.

His intake does not have any provisions for coolant, there is no crossover, there is no thermostat housing on it.

He just needs to know what it takes to drill and tap the front of the heads for some hoses like shown in the first post in this thread. I've never done it...but like was mentioned, try on an old head first. Or spend some time looking inside the cooling passage at the end of the head, there are some small holes that might let you see what's in there. As long as the iron is thick enough to hold a couple threads, and there isn't too much in the way of the drill and tap so they can go in far enough, it should work fine.

Probably want to use as large a fitting as you can, 3/4" pipe would be a good starting point, or 1" if possible.

 

I like it. Now I just need a sbc.

 

Sorry folks, that's not reverse flow. That is simply a way to route the water from the heads, avoiding the intake and thermostat housing and the normal route to the rad.

I'll try and give you the basics to help you understand and I have done the correct reverse flow on special app. race engines many times.

Normally the flow of water would come up from the block into the cylinder heads and intake and out to the rad, correct? The reason for reversing this is the theory that why would you bring extra heat from the cylinders up into the already very hot cylinder heads and top of combustion chambers.

By reversing the flow you take the heated cylinder head or combustion chamber heated water and send it DOWN through the block and back into the rad. That is the idea behind reverse cooling.

The above picture by the O/P has nothing to do with that at all.

 

Traditions is describing a system config. used in counter-flow heat exchangers.
This is fine, unless the heads were to offer so much heat (quantity) to the coolant that the block would be less likely to reject(send) heat, due to the now hot coolant arriving to the "lower" regions.

 

Born to loose, if we could see the entire engine we would probably find out that it is a dry manifold, like some injector manifolds. No T stat because it is designed to go real fast for 1320 feet, then shut off and get towed back to its parking space to waite for the next round if it went fast enough.

You are no where near the cylinder where that head is drilled, you just drill with a light hand and when you break into the water jacket stop drilling.

 

Total flat out racing manifold,I don't care about the reverse flow,just want to know about the cooling,plan on machining some bungs that step up to the flathead hose size,then run thermostats in the hose like they sell for flatheads with a 1inch stainless pipe welded to thermostats so they dot turn in hose,thanks for the help.

 

Ummmm, there's not much chance of drilling into the cylinder unless you aim teh drill down at a 45 deg angle and use about a 6" long drill!
The cylinder normally sits below the head on a SBC.
Most other stuff too.

 

A lot of engineers already figured out the way to cool our engines,.....And for one, I figure they know a LOT more than I do, so,...........

4TTRUK

 

Sorry wrong again. I described what is used on the Chevrolet LT1 engines as well as what we tried and used in Nascar, NHRA, Powerboat racing, etc., etc. Chevrolet engineers designed this system flow to up the effective compression ratio and still burn cleanly for emissions. Pass the heat from the cylinder heads to the block, please guy's I know what the hell I am talking about here. I didn't give you bull crap I found on the internet, I HAVE done this, thank you. For goodness sakes already.

 

I fear I was talking about heat transfer theory. Don't take this as intent to offend, this was simply conjecture, not criticizm. Words often lack emphasis or presence. They are difficult to assemble into fully shared perspectives.
Your experiments in this realm inform us, so thanks.

 

i drilled my intake

 

i've drilled the heads at the back and run -8 return lines to a y then a -10 it worked fine but i prefer to drill the intake it removes any trapped air it was done to get more even temp in the block as the rear ran hotter

 

I did it 30 years ago on my T bucket , machined a piece of cast bar stock to about 3/8" in thickness & placed a pilot hole in the stock to locate it on the head, used cast iron rods to attach the pieces together, into the mill and milled a big arse tapping hole. When I ran it like that I had heating problems with bleeding the air from the coolant system, my solution was to add a third hose on the old thermostat boss , was only a small hose but it did the job, I regulated toerature by a radiator bra, this was used
During the cooler months, still have the heads, stil have the T hope this helps Wayne

 

Old hydroplanes used to do it all the time. On these SBC heads the wall thickness is a little over an 1/8th", give or take.......................

 

Brigrat that is so cool!! Thanks for sharing!!

I lust after those finned breathers, too!!

 

Brigrat thanks for the pic,that's what I wanted to see,I just can't believe it wouldn't work as the intake dumps the coolent there anyway,right?

 

the coolant flows from the head into the intake.

Do you have a picture of your intake? just curious what it looks like at the front

 

pic

 

Ok, it all makes sense now.

 

My hemi truck heads are done like that, there's not much meat there.
Tr waters has a neat gizmo to help for the hemi, might work on the SBC too.

 

These photos I'm seeing ,most have the hose way to low,and would not let water fill head as much as needed=big air/steam pocket above hose/only way for it to work is if there is nearly no load on motor so it makes no Hp/heat.
The heads are designed for water to come out at the top,not below the top.
I see this stuff a lot,and some say it works,there lieing there butt off.
Were theres no water there is no cooling.............
Same goes for water hoses looping up in a big high hump,that hump holds air/steam even if bleed ,as engine runs it fill back up with steam/air and slows flow.
PUT THE HOSES IN THE PLACE THEY WERE DESIGNED TO GO<OR call in a for show only car,