How did that work out? I understand opening the idle tubes and idle bypass restrictors, but don't know what you mean by idle spring. Do you mean the power valve actuating rod spring? If it's too stiff, with a lumpy cam and low vacuum, the power valve will be open most of the time, resulting in the fuel/air mixture being too rich.
The stock power valve rod spring on a Tripower center carb is about 220 grams. I've found that, with a lumpy cam, about 170-170 grams of spring pressure works well with the stock power valve. .Cutting about five turns off the spring is a good start.
Quote:
Originally Posted by i4abuygto
My cam specs are advertised Intake Duration 284 / Exhaust 296
Duration at .050 - intake is 240 / exhaust is 246.
Valve lift is .507 Intake / .510 Exhaust.
Lobe separation is 110
I believe it is Comp Cam XE284H
I originally was not going to run a tripower but decided on the wow factor and put the original 67 numbers matching intake on the shelf.
Here is what I have and did:
I have a numbers matching 67 GTO WS 400 with the stock 670 heads worked by a local head and engine specialist to run stock compression on really good pump gas.
Based on the aggressive cam I was using I had to make some modifications to the original 66 tripower idle circuit and jetting.
Using the original engine block and heads was important to me as I wanted it to look stock when i opened the hood. However, I wanted a 425 hp engine to run on pump gas.
With the advice of the engine builder that did my head work, to achieve better performance, I was directed to a more aggressive cam as I was installing with a 4 speed so the idle rpms were less of a concern to me.
I had originally planned on using a 4bbl carb until I acquired an all original 66 Tripower that I thought would be a better wow factor when the hood was open. I thought the tripower was all good to bolt on and go.
After talking with Mike Wasson, and telling him of the engine configuration, he advised me that the stock 66 tripower would need to be modified to run correctly with my engine configuration. I was advised by Mike that I would need to modify the center carb idle circuit by drilling out the idle ports to his specs and shortening the idle spring to his specs base on the cam I was using and the more aggressive idle that the engine has. I was also advised by Mike on jetting of the carbs, float setting on all carbs and sealing of the throttle plates on the front and rear carbs.
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