Offy C vs. DP
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From: Earth
Offy C vs. DP
Anyone ever switched from a C to DP or vice versa? Just wondering if there's a big seat of the pants difference between the two. I've got a C on my 300 now and it's miles better than the stock 1bbl, obviously, but as I'm kicking around building up the engine further - and realizing a manifold made for power from 2,500 to 7,000 rpm doesn't really seem like the best fit on an engine that will rarely even see 5,000 rpm - maybe replacing it with a DP would be the way to go.
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From: Spokane, WA
Some have reported soggy performance with a C at low speeds but rather than invest in another manifold try a 4-hole spacer. That might help with creating a more columnar flow through the carb and moving the carb base away from turbulence that might be created when dumping into the wide open space of the C. Also, one I know of actually split a C with a divider so that one half the carb fed the front three cylinders and the the other half the back three cylinders...kinda like a dual plane manifold.
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I've got a 1" 4-hole spacer on there now and it definitely helped, changed the A/F ratio across the rpm range.
I'm trying to picture how someone divided a C to feed the front three and back three separately. Must have redrilled the carb mounting studs so the carb was turned 90 degrees? Otherwise you'd have the primaries feeding 1-3 and the secondaries feeding 4-6 wouldn't you?
After spending a couple of hours searching the big six forum at fordsix the guys that swapped from a DP to a C had nothing but unkind things to say about the DP, so I figure there's better things to spend the extra dough on vs. switching.
I'm trying to picture how someone divided a C to feed the front three and back three separately. Must have redrilled the carb mounting studs so the carb was turned 90 degrees? Otherwise you'd have the primaries feeding 1-3 and the secondaries feeding 4-6 wouldn't you?
After spending a couple of hours searching the big six forum at fordsix the guys that swapped from a DP to a C had nothing but unkind things to say about the DP, so I figure there's better things to spend the extra dough on vs. switching.
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From: Spokane, WA
I think he machined a slot running east/west in the manifold and pushed a piece of aluminum or stainless steel or whatever in the slot to divide the manifold. With the primaries facing the engine like on a DP, one primary and one secondary feeds each half of the motor. Since you use a spacer I don't think you would be much ahead by switching to a DP...the ROI just wouldn't be there.
My combo is good to 5000 rpm before it lays over...I don't need to run that fast at all...did several times though just to prove to myself it could do it.
My combo is good to 5000 rpm before it lays over...I don't need to run that fast at all...did several times though just to prove to myself it could do it.
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