Switching to Dual Carbs

[Taylorman]

I have a 455 in my Taylor. Basically stock except for cam. Im running Bassetts and an Offy tunnel ram with a single Edelbrock 750. I experience a hesitation just when the secondaries on the carb start to open. It only occurs just at that point. Once you accelerate past that point, it runs fine. Has anyone ever heard of this problem and a possible solution. I am thinking about switching to a dual carb setup, either dual Edelbrock 500's or dual holleys. I have heard that with a tunnel ram, its best to run dual carbs. Please repond, as I would love to hear what you have to say. Thanks.

[LeE ss13]

Is it a single or dual plane manifold? It's not an Offy 360??? If it is, melt it down into a paper weight. Before going to a tunnel ram, it should work well with a stock manifold. Just my $.13
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LeE ss13

[Craig]

As ss13 said, what's your intake manifold? Not real familiar with the Edelbrock carb (Weber/AFB)but on any vac secondary carb you shouldn't have a bog or "feel the secondaries kick in" Sounds like you're not getting the proper fuel enrichment when the secondary butterflys open. Try and get some tuning directions from Edelbrock. They typically have a good troubleshooting section. I've always liked Holleys. Ran an 850 DP on my 460 jet. Ran great.
Craig

[Thunderbutt]

Taylorman, I have a weiand tunnel ram with 2-750 Holleys that have mechanical secondaries and a 50cc accelerator pumps on both sides. I think you need more fuel when the secondaries open, and the 50cc pumps do that. I don't think the vaccum secondaries work well with tunnel rams. But who am I?.

[Taylorman]

The tunnel ram I have is an Offenhauser with a single carb top. The edelbrock is a 750 with mechanical secondaries. I want to switch to a dual top and dual carb on the Offy ram.

[DetroitJim]

Taylorman, I have had excellent success with Edelbrock carbs, even on a blower. Your problem is very simple, you just need to install larger secondary jets. Just remove the two small cover plates on top, pull out the needles, and pull off the top. Change jets to .113, slap the lid on, and drop the needles in. Wiggle them a little to drop in the jet, cover plates on, done! There are no secondary power valves or enrichment of any kind on your carb. Not needed, there is a flapper valve that controls velocity through the secondaries. There will be no bog with correct jetting. Your carb is set up stock to work well on a mild engine. Your cam, cubes and headers need more fuel. One carb is fine, but if you want a little more just keep your 750 and get another one for about 200 bucks on ebay. Jet them both down a little on the primary, then use a progressive linkage for better fuel use.
DJ

[howard69]

I'm also going from a single edelbrock 750 to twin 650 with machanical secondaries on an offy,not a tunnel just high rise manifold. What jets are recomended on the primaries?