Coolant return on 455 from back of the heads

« **on:** September 12, 2015, 10:45:44 AM »

Can I drill and tap the back coolant ports on my manifold and either return them to the thermostat housing or just dump them out the back? Seems like it would help with cooling of the back cylinders.

Garrett

« **Reply #1 on:** September 12, 2015, 11:11:10 AM »

The front cylinders are the ones that need the cooling.

« **Reply #2 on:** September 12, 2015, 11:11:37 AM »

Do you know how the water goes through the engine?

« **Reply #3 on:** September 12, 2015, 11:12:48 AM »

So the water not flowing out the back of the heads doesn't matter? I know it moves through the block and heads and out the front but I thought it would help the back to have it flow more. I take it there isn't anything I can do about the front.

Yeah, I know how it flows through the block.

Garrett

« **Reply #4 on:** September 12, 2015, 11:30:26 AM »

Quote from: SSpeeDEMONSS on September 12, 2015, 11:12:48 AM

So the water not flowing out the back of the heads doesn't matter? I know it moves through the block and heads and out the front but I thought it would help the back to have it flow more. I take it there isn't anything I can do about the front.

Yeah, I know how it flows through the block.

Garrett

The water flow through the engine goes through the front of the block, up into the heads from the rear, through the heads to the front and out the front of the heads into the manifold. How will relieving the water before it goes through the head "improve" cooling? It will reduce water flow through the head.

The way we have done it is to cut the head gaskets at the air bleed holes to about 3/4", feed the water through the block drains at the bottom of the block and relieve it or if all four corners. This was to prevent sand from clogging up the cooling system on whitewater boats. Big block Chevy, not an Oldsmobile.

GT

« **Reply #5 on:** September 12, 2015, 11:35:39 AM »

This is why I keep dissing the thermostat kits without a water pump.

The water around the front cylinders is lake temp, while the water in the front of the cylinder heads is control temp. That's a 100°F + temperature differential.

GT

« **Reply #6 on:** September 12, 2015, 11:41:13 AM »

I don't see how that is how it works on this engine. From the block the water can come up into the heads starting right at the front of the block. The coolant passages line up from block to head all the way across the cylinders. Why would it need to go all the way to the back to enter the heads?

Garrett

« **Reply #7 on:** September 12, 2015, 11:42:33 AM »

« **Reply #8 on:** September 12, 2015, 11:49:46 AM »

You need to look at the head gasket. The gasket determines flow.

« **Reply #9 on:** September 12, 2015, 11:55:03 AM »

It's opened up to allow flow. I will compare to the new one when I get them in a little.

Garrett

« **Reply #10 on:** September 12, 2015, 12:00:29 PM »

Quote from: SSpeeDEMONSS on September 12, 2015, 11:55:03 AM

It's opened up to allow flow. I will compare to the new one when I get them in a little.

Garrett

What do you mean it's opened up to allow flow?

So the Oldsmobile engineers are idiots?

If you are feeding cooling water from the front of the block, leave the gasket alone. You can literally short circuit water keeping the back of the engine from getting any cooling.

GT

« **Reply #11 on:** September 12, 2015, 12:03:15 PM »

Remember, this engine was designed to have a water pump recirculating water at about 160°F. When the water is hot like that, it requires a lot more flow to keep the proper amount of cooling. I would rather see smaller ports in the gasket, nor bigger. Under cooling is not the issue, it's over cooling.

JMO

GT

« **Reply #12 on:** September 12, 2015, 12:04:58 PM »

The gasket looks like it was drilled in a few spots. The engine was built by Mondello so I assume it was built right. I will just put the stock gasket on and leave it alone. Little bit of copper spray and put the heads on.

Garrett

« **Reply #13 on:** September 12, 2015, 12:07:15 PM »

Quote from: SSpeeDEMONSS on September 12, 2015, 12:04:58 PM

The gasket looks like it was drilled in a few spots. The engine was built by Mondello so I assume it was built right. I will just put the stock gasket on and leave it alone. Little bit of copper spray and put the heads on.

Garrett

Did they build it for a jetboat or a car?

Huge difference.

GT

« **Reply #14 on:** September 12, 2015, 12:22:05 PM »

For this boat that it's in.

Garrett

« **Reply #15 on:** September 12, 2015, 12:37:49 PM »

Quote from: SSpeeDEMONSS on September 12, 2015, 12:22:05 PM

For this boat that it's in.

Garrett

Just a question.

Why do you think it is requiring modification?

GT

« **Reply #16 on:** September 12, 2015, 12:54:56 PM »

My passenger side was getting hotter than the drivers side. I think there was just too much crap inside the block that was restricting flow. I've checked the water lines to the headers and the pisser. Temp never got over 130. I cleaned the block out and going to run it. Plugs all looked good. For some reason the passenger header was a couple hundred degrees hotter.

Garrett

« **Reply #17 on:** September 12, 2015, 01:03:50 PM »

Quote from: SSpeeDEMONSS on September 12, 2015, 12:54:56 PM

My passenger side was getting hotter than the drivers side. I think there was just too much crap inside the block that was restricting flow. I've checked the water lines to the headers and the pisser. Temp never got over 130. I cleaned the block out and going to run it. Plugs all looked good. For some reason the passenger header was a couple hundred degrees hotter.

Garrett

This is going to sound retarded, but. ..

Sounds like a carburetor issue to me.

Unless of course there was a shit ton of sand/debris in the block.

« **Reply #18 on:** September 12, 2015, 01:06:49 PM »

Carb issue with 2 new 600s on a tunnel ram? There was literally a shit ton of sand in the block. It took like 10 minutes to flush both sides of the block with the freeze plugs out and running hose to water through the front of the engine.

Garrett

« **Reply #19 on:** September 12, 2015, 01:12:18 PM »

Quote from: SSpeeDEMONSS on September 12, 2015, 01:06:49 PM

Carb issue with 2 new 600s on a tunnel ram? There was literally a shit ton of sand in the block. It took like 10 minutes to flush both sides of the block with the freeze plugs out and running hose to water through the front of the engine.

Garrett

Sorry, had no idea what you had for carburetion.

Still, header temperature has little to do with water temps.

GT

« **Reply #20 on:** September 12, 2015, 01:21:16 PM »

Quote from: GT Jets on September 12, 2015, 01:12:18 PM

Sorry, had no idea what you had for carburetion.

Still, header temperature has little to do with water temps.

GT

I was thinking more like water flow issue and the passenger header wasn't getting enough water hence why it was hotter. The plugs all looked the same, no lean issue on the passenger side.

Garrett