random stupid question

[rfisch]

I'm putting a 4bbl in place of my old 2 on my 289 and need to get a new carb spacer of course. My question is what is the purpose of the spacer (just for heat?) and why am I having trouble finding one that has a outlet on the back to run a hose to my valve cover like the original? And what is the point of the hose that runs to the cover? Most of the ones that I have been finding don't have that outlet. Is it necessary?

[Phillyfanfrombirth]

Ok... I'll ask...

Why do you need a spacer?

Now that that is out way...

Get a different grommet, and stick a breather in there...

[rfisch]

I'm sorry, that confused me. Are you saying that I don't need a spacer. I assumed that the hose really didn't need hooked up to the valve cover, like you said, just stick a breather there, I just thought that if I did need the spacer, I would hook it up the way it was when I took it off.

[Rev]

1.) A carb spacer can be for different reasons. The original phenolic resin spacer was to insulate the carb from engine heat helping to reduce fuel percolation in the float bowl.

2.) Sometimes a spacer is added to increase the plenum volumn in the intake manifold. It depends on how your engine is set up as to whether a spacer helps or hurts perfomance. There are numerous designs and heights available. Also it can lead to hood clearance problems.

3.) They are relatively inexpensive, so it won't hurt to try one even if it doesn't help.

4.) The hose to your valve cover is for the PCV valve. You need that to pass almost any vehicle inspection in any state. Most aftermarket 4 bbl carbs have a vacuum connection for that application. Otherwise you can run that hose directly to the intake manifold. You really need a PCV valve anyway just to get the blow-by gases out of the crankcase.

Rev

[Phillyfanfrombirth]

Yeah... the emissions thing... In PA pre-75 autos are exempt, didn't think about that.

I know for sure that Holleys have that connection, but wasn't sure about Edlebrocks...

As far as percolating thing... is that generally an issue with aluminum intakes? Since the aluminum dissipates heat much more efficiently?

As far as the carb spacer... watch clearance with the hood if you take that route. In effect, you will push the RPM band of the intake higher, the higher you go... sort of the difference between a normal manifold and a high rise manifold.

[Rev]

I know in Texas I don't have to get on the dyno to check for emissions in my '66. The law does require that all original emissions equipment must remain on the car though. Mine came with a PCV valve, so I have to keep one on the engine to pass. I would have one anyway as it doesn't really hurt performance any.

My Road Demon also has a vacuum connection for the PCV valve. I'd bet all the new 4bbl after market carbs do. I don't have any spacer on mine (Performer/Raod Demon) and don't believe a spacer would help me anyway. Also, I don't have any hood clearance to spare with my home made cold air/ram air set up.

Rev