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Freshman User
Joined: Apr 2002
Posts: 45
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From: St. Petersburg USA
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I have learned that the Clifford 2bbl adaptor plate will mount to a stock 1bbl manifold. I'm considering doing this by mounting a 350cfm 2bbl on my stock manifold. I'm also adding a set of headers. Has anyone done this or know what the power advantage might be over the stock setup? Is the stock manifold too restrictive? Thanks for the input - BUBBA
Laughing Gas
Joined: Apr 2001
Posts: 1,024
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From: Elon, NC
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Bubba,
Although I replaced my 300 six with a 351W I've read a lot about these engines. Most will tell you the stock manifold is restrictive and should be replaced. From what I've read, the split manifold from the EFI six's is as good as aftermarket headers for this engine.
Or so they tell me......
Ron
Although I replaced my 300 six with a 351W I've read a lot about these engines. Most will tell you the stock manifold is restrictive and should be replaced. From what I've read, the split manifold from the EFI six's is as good as aftermarket headers for this engine.
Or so they tell me......
Ron
Elder User
Joined: May 2002
Posts: 627
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From: Claremore, Ok 74017
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Can't tell you too much of the 2 barrel but I have maxed out intake serval times accelerating on the highway. I would recommed you get a JcWhitney catalog and look at a Offenhauser 4bbl intake and maybe a 500cfm carb from Edelbrock or Holley. Run around $400-$500. Also the later EFI Exhaust flow comparable to headers from what I have seen, and Dynomax also makes a good header. Use a 3inch exhaust out and have one stout little six for not much in it for improvements.
Postmaster
Joined: May 2002
Posts: 3,241
Likes: 3
From: Broken Arrow, OK
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The EFI dual manifolds suck compared to headers. I put a set of Hedman headers on my 90 with EFI and gained 7 mph in the quarter mile. I also gained a lean condition on the top end that won't let the engine make any power above 3100 rpm. When I get the fuel curve fixed and find the 700 rpm I lost I should get a bit more. There's and old racer saying: "The worst header is better than the best manifold". For $120 you can't beat the Hedman headers.
Junior User
Joined: Mar 2001
Posts: 80
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From: Temperance USA
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I tried the clifford adapter and it helped nothing and hurt the off idle power(there's a reason NASCAR uses restrictor plates). After a lot of trial and error, my '78 F150 300/3spd ended up with with a 390 Holley(you're good for well past 4000rpm), on an Offenhauser 360 dual plane, I don't remember the runner size, but they were the smallest Clifford headers, recurved distributer, and valve timing advanced a couple degrees with an offset key from Clifford. It ran with the 351's of the day and sounded like an Austin Healy. I'm sure you'll come up with your own setup, but I was very happy with this one when I had it. Good Luck
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