Rear water crossover on intake?

TFD32 · Oct 22, 2017

Have done some reading on using the rear water crossover passage on my Edelbrock Performer 351w intake. Has anybody used it and had a problem. I've got a 94 roller block and Trickflow heads. Some say that it does make a difference others say no difference. Want to see what you guys think.

blubuckaroo · Oct 22, 2017

On my 302, I've had Edelbrock Performer intakes of the rear crossover variant and also the one without. No difference in cooling or in priming the cooling system.
Since the heads are the same as on the 351W, I can't see how that application would be any different.

Dbarnes72 · Oct 22, 2017

Researched it a few years back because I have an Edelbrock manifold on a 351W that is tapped but I never found any compelling evidence that made it seem worthwhile. Don't have any personal experience to share. Should be some old threads here in this section.

TFD32 · Oct 22, 2017

Tried the advanced search, didn't find much at all. Might not of used the right wording?

gr8scott · Oct 22, 2017

Try this, it works!
http://reedweb.net/classicbroncos.search.html

Broncobowsher · Oct 22, 2017

I tapped the rear water for the heater. Being in AZ I don't need much heat. So pulling water before the heads results in cooler water then the front of the intake (after the water has been through the heads). It cleaned up a little bit of heater hose plumbing. And left both holes in the front of the intake for temp senders (gauge and EFI).

At one time I had the other rear port plumbed into an oil cooler. Eventually removed the cooler as I wasn't running it hard enough to warrant it.

None of the messing around with it ever made any difference in cooling. I was fighting marginal cooling at the time as well. Finally did a few things correctly and never bothered with the crossover anymore.

73azbronco · Oct 22, 2017

I actually bought the earlier edelbrock version which has the crossover and put it in my storage area. Probably never use it. The performer on my stroker does not have it, supposedly that crossover was used for EGR coolers in the day, not needed these days.

ntsqd · Oct 23, 2017

Think about what that cross-over could accomplish. The rear end of both heads should be about the same temperature, and pressure. Connecting them together won't increase coolant flow, it will only equalize both the temperature and the pressure at the rear of the heads should there happen to be a difference otherwise.

What might be a benefit would be if you could pull coolant from the rear of the heads and port it directly to the coolant manifold right behind the thermostat. Then the coolant could exit at all 4 corners of the engine instead of only at the front.
I did this mod to an intake that I ran on the Ranchero's 302. The results were that the engine took a little longer to warm up and while warming up the rear of the heads were about 10°-15° warmer than the front of the heads (temp gauges at both ends). Once warmed up I didn't notice a huge difference in cooling. Surprisingly I never had any trouble purging those local high spots of air.
Given the added complexity for the little gain I've not done this mod again.

JB Fab · Oct 23, 2017

It works if you plumb it to the water neck

I did it on our 351W, but I "T" it and plumbed it to the water neck with a ball-valve. Closed for winter, open for summer, makes about 10* difference when its hot out

ntsqd · Oct 23, 2017

Putting into the water neck partly by-passes the t-stat, which will reduce block pressure. Not something I'm willing to do when cooling is paramount.

tirewater · Oct 23, 2017

The 1983-1985 Mustang 5.0 (carb) intake had the rear crossover port.

Coolant gets pushed to the back of the block, up and through the heads to the front of the intake. All things being equal coolant would just sit in the crossover.

In all likely hood it was simply put in to allow for more sensors.

I have the Edelbrock 3721 intake and installed a second coolant sensor in one of the rear ports.

jckkys · Oct 23, 2017

The 351W Edelbrock Performer EGR is the only 351w Performer intake with the cross over I know of. It provides a place to install the ported vacuum switch that activates the EGR valve. Non EGR intakes have no use for one. No Ford OE intakes had them until they needed EGR. When you say you may want to use it, I have to ask what for?

Broncobowsher · Oct 23, 2017

tirewater said:
The 1983-1985 Mustang 5.0 (carb) intake had the rear crossover port.

Coolant gets pushed to the back of the block, up and through the heads to the front of the intake. All things being equal coolant would just sit in the crossover.

In all likely hood it was simply put in to allow for more sensors.

I have the Edelbrock 3721 intake and installed a second coolant sensor in one of the rear ports.

That's the era where Ford was doing water cooled EGR with carburators. Even if that model didn't have it the engineering was probably a holdover from those that did have it.

TFD32 · Oct 24, 2017

I have both the non-egr intake and the intake with the egr. The egr intake has a lower carb platform. I'm going to be running propane so i'm trying to keep the height down for hood issues. The intake has a plug that i can block the rear water crossover with, so i was just trying to determine the pros and cons of using it.

ntsqd · Oct 24, 2017

Don't propane mixers need coolant to keep them from icing up?

TFD32 · Oct 24, 2017

ntsqd said:
Don't propane mixers need coolant to keep them from icing up?

Yes, most of the set ups that I have seen use the return from the heater core.

Rear water crossover on intake?

TFD32

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blubuckaroo

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Dbarnes72

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TFD32

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gr8scott

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Broncobowsher

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ntsqd

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JB Fab

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tirewater

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jckkys

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ntsqd

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