Carb spacer plate.. open rectangle or dedicated bores?

[birdsandbees]

Putting my engine all back together and while cleaning my carb realized back in '89 or so I put the wide open spacer plate under the 750 Holley I bought at the time. Has of course always had the "whistle" on light throttle taps.

Should I be returning to dedicated bores from carb to intake manifold?? I am running the factory dual plane and I have a dedicated bore spacer plate (that is currently tapered bores) that I can mill as straight throughs to match the 1 11/16 of both the carb and manifold ports.

Also I have never had any issues of black plugs, running rich, etc... but should I be returning my factory stock 383 to a 600 CFM carb from this 750 x 65-3310 Holley??

Thanks!

[PRH]

Depending on the rest of the combo, the open spacer might make more top end power than no spacer, or a four hole spacer. You'd just have to try them both to see which you prefer.
There really isn't any "right or wrong" when it comes to carb spacers...... And since they're fairly cheap and easy to test, you should try both and see how they affect your combo..... Or if you can even discern any difference.

If I had to make a "one and done" decision, I'd match the 4 hole to the manifold and run that. 

[Dino]

I'd give the 4 hole straight through a shot.   

[birdsandbees]

Thanks guys... I'll make sure the 4 hole spacer is thick enough for the 750 arms and if so mill it straight tomorrow and then find some proper gaskets for same. I already have open style gaskets in the shop if I need to use the open spacer that is about 3/16 thicker. Be good if the 4 hole works and I get a bit of hood clearance back as I am slamming a ramcharger hood seal down on top of it.

[BSB67]

Because it is a 383 with a 750, I would go 4 hole.   

[birdsandbees]

THANKS!