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Intake Port size vs Carb Port Size


bonkas

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Hey Guys,

Have run into another issue which I am having trouble finding a clear answer for.

I am looking to run a pair of Dellorto DHLA 45's on my 4g63.

I am at the point where I need to make a decision on Intake Port Size, the valves have been enlarged so I need to also increase the small port for more flow.

The carbs I have are 45's, One which is in need of repair and they both need a rebuild and misc parts replaced.

The real question is do I run 45's with a smaller choke size (34mm or so, 36-38mm for peak power around 6000rpm ish) or do I sell these carbs and pick up the 40's which are on trademe at the moment which have been rebuilt and tunes for a 1600, I will just need to adjust the chokes etc to suit the larger capacity engine.

Do I port match to 40mm and run the 45's anyway or is this a poor thing to do?, port match to 45mm with the 45mm carbs or get the 40mm carbs and go to a 40mm port.

The engine is having compression increased to around 10.5:1, port and polished head (bar intake), 2mm larger intake and 1.5mm larger exhaust valves.

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