[western star]

If you have a dual plane spread bore intake and you are mounting a square bore (Holley) carb to it does it matter if you use and open plentum gasket instead of a square bore gasket? With the 4 hole gasket you do get the seal on the divider on the intake. Would it make any difference off idle. Just curious.

 

[fried_guy]

I've used both on the same engine and noticed absolutely no difference.

 

[western star]

Fried_guy and by the way I love your name, thanks for that.

 

[4 Jaw Chuck]

Cut the gasket to fit the manifold, any gasket material left hanging in the opening will eventually get fuel soaked and could possibly hook the throttle plates open when you least expect it or fall into the plenum...usually at WOT!

I wouldn't worry about a plenum divider seal, it won't make a difference.

 

[musky2]

spread bore intake with square Holley

The carb fits or bolts on ; but you need to get a plate that is a little thinner than a quarter inch . They dont put them in the intake boxes ; I dont know why! It looks like a brass or metal spacer that is open square: this makes sure there is no gasket leak (carb.) because with the spread bore intake opening there is not much of a sealing area. It might leak and it might not without this plate but it will be close. They are about 6 bucks and you can find them in the Holley parts section at the hotrod shops. Check a few different places because they are hard to find and they dont stock very many. Or you can use one of the inch thick aluminum adapter that looks like a spread bore base but tapers into a square Holley base : they are about 12 bucks. Ive used both and felt no difference. I would not just bolt the square Holley onto that s. bore intake that is not a close match at all!

 

[western star]

I am useing a base gasket made by Holley. It's about 1/4" thick. It is the one that is open in the centre. The reason I ask is I am trying to get rid of an off idle stumble from a new Holley 670 Street Avenger. I've change cam/throttle postions, increased and decreased pump nozzle sizes, adjusted floats, check fuel pressure, Checked choke, checked vacuum advance and manifold vacuum, had 2 or 3 beer, set up fuel mixture, installed better air filter, played with timing, can't think of anything else right now but I still have a hesitation at any speed when stepping on the throttle even lightly. I had it also when taking off but managed to correct that part. It's on a 340 Dodge motor with about 15000 miles on it. Here's the other thing. The Edelbrock I took off had the same problems. I run electronic ignition, ballist resisitor and external coil. What else should I check?