[Bad bird 169]

Does anyone offer a cooling kit package for connecting the rear of the cylinder heads to the water crossover?

[JLMounce]

I don't think I've ever seen a specific "kit" put together for this. There are some speed parts that can help put it together. From what I've seen those are centered more around race use and omit a thermostat all together.

If this is going in a street car, you want/need a thermostat.

It's a little bit more involved, but take a look at this video from Fast Monty. What he did on his engine is probably the best you can do for a street car specifically.

https://www.youtube.com/watch?v=v_qUY4E33r0&t=188s

Long story short, yes tying both heads together at the back to move fluid through the core and back to front of the engine, does help reduce temps at the back of the heads. However, you really need to dump the coolant into the cross-over, not back into the pump where you're adding that hotter fluid to the rest of the engine, bypassing the radiator. This is the same reason AC equipped cars come with heater block-off valves. It allows the condensor to work better and doesn't shove hot fluid back to the front of the engine.

This requires welding a bung to the cross-over to achieve.

I will say however, that unless you're doing sustained higher load, higher rpm driving, like open road racing, circle track etc. There's probably not a huge benefit in doing so to save 10-15 degrees at the back cylinders. What I do personally is tune around those cylinders specifically.

[steve25]

You can do this with iron or aluminum heads , or with iron heads you can weld a thick washer to new freeze out plugs to go in the rear of the heads and then before installing them drill and tap them for 3/8” pipe, then use 90 degree fittings to get the lines top side.

Note that if you do the freeze plug deal that as I said the spacer washer needs to really be thick because the exh port runner is right behind the freeze out plug.

[JLMounce]

It is important to note that the above method, while great, completely bypasses the heater core. Fine for a race car, probably not practical for a street car. Since this is the street section, I'm assuming we're talking about a street car.

[performerrpm]

ive been reading up on this lately myself...theres a guy on youtube...forgot his name but he has a pretty elaborate setup on his pontiac. near as i can tell, the way steve posted is the most affective situation. but alot of others have had good luck looping the drivers head to passenger head with a T then onto the heater core. this will be how i do it along with the 421 passage drilled in the deck/heads.

im not 100 why you couldnt loop the driver head to the crossover and leave the passenger side as the only feed to the heater core

[tc]

I use a Y at the rear of the heads, then to the heater core, out of the heater core to one of the threaded holes on the top of the crossover of the intake manifold. Also, plug the nipple on the timing cover the heater core coolant hose used to go to.

[Nobuddy]

If it matters, the heater and defrost will be effective quicker if you plumb to the original location on the timing cover.

[Joe-Touring]

Another way to help cool the rear of the engine is to drill/tap the forward 3 cooling holes on each side of the block. This forces more coolant to the rear of the block, up into the rear of the heads, and then forward to the crossover.

As far as I know, Steve Barcak developed this method. He also advocates for drilling the 421 cooling passage in the heads and block, adding coolant flow to the hottest part of the heads. See post #5 in this thread:

https://forums.maxperformanceinc.com...d.php?t=583733