So a friend of mine is running her '76 Ford mud racing in the Stock Class around here. Her 390 has 2bbl that needs rebuilt, replaced, or something along those lines. She is restricted to factory exhaust manifolds in this class so would it be worth it to pick up a cast iron 4bbl manifold? I am thinking she might just be better off with a Holley 500cfm 2bbl. What are your thoughts?
Can she run a factory aluminum intake? The exhaust is the biggie - fe log manifolds suck the long branch 427 manifolds are huge money but look for a set shorty branch manifolds (406 high po) they will make a huge difference (if they will fit the chassis) - I would do that before I worried about the induction
If street manners (and mileage) aren't a big consideration, a 500 cfm 2-barrel on the stock intake will work fine. If it's a daily or semi-daily driver too, a 4 barrel carb and intake will work a bit better. On a near-stock or mildly warmed motor, tracking down big $$ and/or rare exhaust manifolds (if they'll even fit, which I doubt) won't gain you a ton of power.
Wow, the FE truck manifolds are really restrictive maybe do some relief work inside of them to slightly smooth flow - what exhaust pipe/muffler restrictions?
That stinks, the exhaust side is where FE's really need help, especially with those restrictive exhaust manifolds. If it was me, I'd swap out the pistons for those from an earlier 390, in '70 or '71 Ford started putting 410 pistons in 390's to get them an extra .010 down in the hole and cut the compression down to 8:1 or something like that for emissions. Being a stock class, that's probably not allowed by the rules, so if you don't want to pull a Smokey Yunick I'd suggest checking out The Great FE Intake Comparo by Jay Brown, who races FE's and has forgotten more about them than most of us will ever know. Here's a link: http://fepower.net/GFEIC.html. He tests basically every intake that is (or has ever been) available for the FE, with dyno charts for each one. I don't know which one he recommends overall. Personally, I'd recommend a single-plane and a 750cfm Holley, the FE is a torque monster as it is so the extra top-end you get from the single-plane might be helpful.
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