cylinder head external coolant lines

[Mike Peters]

I have conventional port SBC heads that are tapped for external coolant lines. Lines from the intake side center to the water neck and lines from below the center exhaust ports to tapped holes in the water pump. Also included in the system are the lines from the rear of the intake manifold to the manifold coolant crossover. This is a nitrous combo that will be run run in 1/8th mile events. I bought the engine used and haven't ran it myself so it was already plumbed with this system. I'm in the process of replumbing it as the previous workmanship doesn't please my eye. I am asking how much difference having this system in place will help as opposed to buying pipe plugs and blocking it off? The coolant lines and fogger make everything very packed and crowded for room.

[Matt Compton]

Man if you can .... leave it the more water you can get in/out of those places on a sbc the better. Will help keep head gaskets in it for sure.

[JeffMcKC]

Cooling the two exhaust valves that are close is a good idea, and will help the chambers out, leave it

[ROB]

The end plumbing does a good job of bypassing the cylinder head with water. Exceptions are cases where the deck holes have been modified to allow a LOT of water in the center of the head & flow across the head from exhaust side to intake, then out the ends.

If the heads have "normal" holes in the deck I'd get rid of the end plumbing. I've taken 4-corner temp measurements on a small block with a belt driven water pump & found them to be within ~3°-4°F so there's no reason to believe the back of the heads are hot or whatever.

I'd also consider either welding extension nozzles to the fittings going in under the paired center exhaust ports - OR - connect the water pump end of those hoses to the suction side of the water pump (center top of the stock Chevy housing). The latter will probably help coolant flow on the lifter valley side of the jacket and it will draw coolant from that area across the hot bridge between the center cylinders.

[Mike Peters]

Thanks for the info and the PM guys. I'll upgrade the lines and keep the system in place.

[Greg G]

I would use it. That is primarily a circle track mod, but it also helps drag engines.

[Chris Uratchko]

Originally Posted by ROB

The end plumbing does a good job of bypassing the cylinder head with water. Exceptions are cases where the deck holes have been modified to allow a LOT of water in the center of the head & flow across the head from exhaust side to intake, then out the ends.

If the heads have "normal" holes in the deck I'd get rid of the end plumbing. I've taken 4-corner temp measurements on a small block with a belt driven water pump & found them to be within ~3°-4°F so there's no reason to believe the back of the heads are hot or whatever.

I'd also consider either welding extension nozzles to the fittings going in under the paired center exhaust ports - OR - connect the water pump end of those hoses to the suction side of the water pump (center top of the stock Chevy housing). The latter will probably help coolant flow on the lifter valley side of the jacket and it will draw coolant from that area across the hot bridge between the center cylinders.

At most, I like to run a -3 or 4 line from the back upper area of the head to bleed.... and that way it's not stealing too much coolant from the head.

Another note worth mentioning, is that little trick of putting water under the exhaust ports in the center...... probably minimal gain, unless you go all the way into creating a water port THRU the entire head, so a stream of water can pass between the seats/ports and to the valley side of the head, pulling heat away from that area..... it's not an easy task either....

Then you need to force water thru that port.... and that involves more than just a fitting on the outside. It's pretty involved if you really really want to cool between the runners.

That old chevy power book gets into it with the 18 degree head, but on a 23 degree head, and the way their cooling systems are designed it's more nerve racking to run water between the seats and ports. Unfortunately it's a must for a turbo engine and it will make the head live.

[Shelton_Barrs]

Chris,
Back in the day when I was fooling around with dirt track stuff a lot of guys were trying to push water into that area between the ports. We tried that but then decided that since that area was a "hot" area that the pressure would be higher in that area. So instead of trying to push water in, we pulled water out. Seemed to work. Your thoughts?

[Deakins]

We always pull the water out of the cylinder head between the center two exhaust valves. If the application was severe enough (endurance engine) we would pull from the ends as well. We really found a difference during tear downs and didn't have to nip the head/deck as often. Just my .02

[ERV JR]

got some pics or diagrams ?

[ROB]

Originally Posted by Chris Uratchko

At most, I like to run a -3 or 4 line from the back upper area of the head to bleed.... and that way it's not stealing too much coolant from the head.

Another note worth mentioning, is that little trick of putting water under the exhaust ports in the center...... probably minimal gain, unless you go all the way into creating a water port THRU the entire head, so a stream of water can pass between the seats/ports and to the valley side of the head, pulling heat away from that area..... it's not an easy task either....

Then you need to force water thru that port.... and that involves more than just a fitting on the outside. It's pretty involved if you really really want to cool between the runners.

That old chevy power book gets into it with the 18 degree head, but on a 23 degree head, and the way their cooling systems are designed it's more nerve racking to run water between the seats and ports. Unfortunately it's a must for a turbo engine and it will make the head live.

That's the way it was done in the old days on the turbo big block stuff for marine use and it does work but is a pain in the ass to set up. At one time I did some of the required machining for a guy who was doing twin turbo 353 CID big blocks with Pontiac pro stock heads on them & his finished package made stupid power & would live long after many hours dithering near WOT in a 40' boat.

For the plumbing in the back of the heads & bleeding, I'd rather vacuum fill the system. The tool costs about the same as it will for lines & fittings to set up an engine and it's completely effective when used according to directions.

[ROB]

Originally Posted by Deakins

We always pull the water out of the cylinder head between the center two exhaust valves. If the application was severe enough (endurance engine) we would pull from the ends as well. We really found a difference during tear downs and didn't have to nip the head/deck as often. Just my .02

Did you notice what looked like better heat distribution on the intake side of the deck face when you pulled water out at the exhausts?

[Shelton_Barrs]

Originally Posted by ROB

Did you notice what looked like better heat distribution on the intake side of the deck face when you pulled water out at the exhausts?

It seemed to help us but we were also playing with different size holes in the deck plugs also.

[Deakins]

We noticed an all around improvement during tear downs with our set ups.

[ROB]

Originally Posted by Deakins

We noticed an all around improvement during tear downs with our set ups.

Not at all surprised.