Thread: Roush 427 SR verses R
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Old 01-26-2021, 05:32 AM
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Join Date: Jan 2017
Location: Glendale, AZ
Cobra Make, Engine: FFR MkIV 427
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SR has dual plane manifold (street/torque oriented) vs single plane on R (more WOT/high HP oriented). The car is so light, you can really go either way.
I have the Craft equivalent of the R with a Performer RPM Air Gap. I ended up switching to an EFI ($1200 system) to tune around the low vacuum, which the carb didn't like below 1800 RPM. If you choose to go this way, let the engine builder know and ensure they use an EFI friendly camshaft.
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