carb spacer on pre-emissions 300

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carb spacer on pre-emissions 300

Postby thunderb » Tue Oct 11, 2005 9:05 am

I'm removing the non-funtioning EGR and failing emissions equipment off my '79.

Is there a carb spacer on the pre-emissions 300's and 240's that would replace the EGR plate on my 300 or should I just bolt my carb directly to the intake?

As of right now, i'm rebuilding the carb and trying to get rid of a rough idel and improve my 11 MPG gas mileage. Seems like I should be getting at least 15 for a base model 2wd 300 3 spd, Stock tires and wheels, and a 2.75 rear gear.
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Postby benwantland » Tue Oct 11, 2005 9:18 am

Yes, there is a non-emission spacer, and you have to either find one and use it, or make a block off plate that covers where the EGR valve bolted onto the stock spacer, because you have to run one of the two to cover up the hole in the carb pad of the intake manifold where the exhaust gas comes out for the EGR system.

Be aware, when scouring the junkyards, that there are two bolt-hole-spacings, and also, some spacers have vacuum ports and some don't. Here's a picture of a couple of non-EGR spacers:
Image
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Postby thunderb » Tue Oct 11, 2005 9:53 am

What mileage do you get with your truck? Most of the threads I see about mileage involve the later model fi 300's or 4X4's. I'm curious as to what a plain 2wd 300 gets for mileage.
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Postby benwantland » Tue Oct 11, 2005 10:19 am

With careful - but not necessarily slow - driving, I get about 19 mpg with my four barrel. Did about the same with the one barrel Carter.
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Postby SuperMag » Tue Oct 11, 2005 10:53 am

You don't necessarily need a spacer... The EGR hole in the intake manifold is just the right size for a pipe tap; 1/2" or 3/8", I forget which (it's been a few years since I've done it). Tap the hole, screw in the pipe plug, grind & file it down flush with the manifold...

However-- having the carb sit directly on the manifold does create one interesting problem. I the summer time, the carb gets too hot after I shut the engine off. If I run into a store for a minute or two, come out and restart and go about my way, the engine surges and runs rough for a minute or two until the incoming air charge cools things back down.

But that's just a hot weather problem. In the winter, the carb heat never worked better!
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