225 Offy Intake Mods.

Hi Everyone, I am new here and wanted to share the mods I made to a Offy 225 intake back in 2016.


I wanted the advantages of the 225/Offy intake manifold over the stock one but did not want to be limited to using a 4V. I cut the 4V hole top plate out so it can now be used along with a simple adaptor plate, with any 2V carb, 2V TBI or even back to the 4V. I built the 225 in my Commando around low/mid power and so the other change I made was to close off the two “communication” passages at the base of the divider. Modern day these passages are made in the way of a slot at the top of the divider of a dual plane.
These cut outs in the divider wall enhance top end and make the manifold less sensitive to a given carb CFM. Since this Offy manifold was originally designed for use with a 4v carb, these cut outs made sense.

The downside and the reason I eliminated them is that low speed torque suffers ( this is because the communication holes actually makes the manifold in fact more like a open or single plane) as well this hurts idle thru low speed cruise vacuum and throttle response.
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welcome from Oklahoma! I happen to be in Pagosa this week because my kids wanted to go skiing.