EGR valve on aftermarket SBC intake manifold?

Started by Baby Deuce, April 18, 2007, 04:30:07 PM

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Baby Deuce

I know most people block them off, but imagine for a moment that you wanted to actually run a functional EGR on a motor!

I have a Holley Street Dominator, the old single plane version, that has a provision for an EGR valve on it. The intake accepts both Holley and Q-jet carbs. I have a good Q-jet to run with the intake.

The EGR mounts at the rear of this manifold, instead of on the passenger's side like most stock Chevy intakes I've seen. If you look inside the plenum area, there is a hole at the bottom directly under where the carb would be mounted. I assume that this feeds the recirculated exhaust gasses into to engine when the EGR valve is open?

So, my questions are as follows:

1. Once the EGR valve is mounted, where does the vacuum hose go to? Ported vacuum, manifold vacuum, or some other specific port on the carburetor?

2. Are all Chevy V8 EGR valves the same? I know they share a common mounting pattern. I have a good valve from an early 80s G-body that had a 305 in it.

3. If I decided not to run the EGR valve, where can I get that hole in the plenum welded up good enough so that I'd never have to worry about the 'plug' popping out?

I'm not opposed to running an EGR. It doesn't really hurt anything, the intake was designed to work with it, and Ford STILL uses them to gain the minute edge they provide in fuel economy. I'm no tree-hugger, but I thought I might try running the EGR this time around, to make up for all the times I blocked them off and threw them away! :D
If you are not criticized, you may not be doing much.

Dave

Well I guess If you want to... About the only thing I can add is just make a plate to block off the egr port and use the bolts If i remember right there are 2  and some hi temp silocone and you should be good to go.
Dave

Baby Deuce

Quote from: "jusjunk"Well I guess If you want to... About the only thing I can add is just make a plate to block off the egr port and use the bolts If i remember right there are 2  and some hi temp silocone and you should be good to go.
Dave

I have made block-off plates for stock intakes in the past and they work great, but look dumb. Like something is missing. I'd rather see the EGR there and hooked up than a plate in most cases. This intake has the oil filler tube on the front which is a big reason that I am using it, and I thought I'd run the valve too.

It seems to me that vacuum wasn't always run directly to the EGR valve. I can't find any info to verify that, but from what I remember while pulling them off in the past, I think that the vacuum ran through a thermostatic vacuum switch in the thermostat housing or the water crossover on the manifold. Is that the correct way to hook it up? Anyone know?
If you are not criticized, you may not be doing much.

enjenjo

QuoteI think that the vacuum ran through a thermostatic vacuum switch in the thermostat housing or the water crossover on the manifold. Is that the correct way to hook it up? Anyone know?

Yes, thats the way it's done.
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