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Im looking for the best carb spacer to run on my 400. Cant decide if i should go 1 inch or 2? Open or 4 hole? It will see mostly street and strip. Its a 2wd F-150 with a built 400. Any suggetions will be great.
I would use the tallest spacer that I could get under my hood, and I would use a 4 hole style. The 4 hole spacer helps to reduce turbulence in the carb venturi, which provides a better throttle response.
to add...any spacer that does not completely seperate the primary and secondary flow in a dual plane intake will hurt perfomance significantly. It attempts to turn a dual plane into a single.
keep in mind you want ot get an air cleaner in there that will do some good as well. I have a 1" spacer with a diesel air cleaner which has a lot more breathing area and it just fits.
The only way to know for sure is to install the manifold and carb and then use the cowl as a reference point and see how much room you have. There is no formula, it's measure as best you can and trial and error.
Im currently using a 2" single plane spacer with a dual plane intake in my 351m, I have a single plane intake but what would be worse for my mild low comp ratio 351m:
1. to use the single plane intake with the sigle plane spacers
2. keep using the dual plane with single plane spacers
???
Im currently using a 2" single plane spacer with a dual plane intake in my 351m, I have a single plane intake but what would be worse for my mild low comp ratio 351m:
1. to use the single plane intake with the sigle plane spacers
2. keep using the dual plane with single plane spacers
???
I think that your dual plane intake is acting like a single plane now. So there is no advantage either way. I would be looking for a 4 hole spacer, myself.