400 adding a 4bbl question

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Apr 6, 2007 | 12:15 PM

cowboyty

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400 adding a 4bbl question

I have a stock 400 with stock exhaust manifolds running a 2bbl carb. I am replacing the carb with a Holley 650 I think model 6210 manual choke and manual secondaries. The intake manifold I bought from a salvage yard and its an Offenhouser intake. It has been modified by welding plates onto it to eliminate the valley pan, and was told it probably came off a pulling truck or something. I didn't know if anyone has heard of these intakes or any idea of what it might gain me in horsepower?

Thanks

Apr 6, 2007 | 01:16 PM

packlet

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From: Berkeley

according to http://www.mustangsandmore.com/ubb/D...1CIntakes.html
there were several Offy dual ports avaialble for 351m/400's.

dunno what the differences between the models might be, but i've heard good things about 'em, although they seem to be pretty hard to find these days.

Offenhauser Dual Port 400 (P/N 6033-DP)
- low rise dual port with Holley carb bolt pattern
- not CARB emissions approved
- advertised RPM range: idle-???
- '71 later 400

Offenhauser Dual Port 400 (6034-DP)
- low rise dual port with spread bore carb bolt pattern
- not CARB emissions approved
- advertised RPM range: idle-???

Offenhauser Dual Port 351M (P/N 6141-DP)
- low rise dual port with Holley carb bolt pattern
- not CARB emissions approved
- advertised RPM range: idle-???
- '75 and later 351M

Apr 6, 2007 | 01:23 PM

beartracks

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From: Albuquerque

Valley pans on a 400 are recommended but not required. If you have plates welded on the sides of the manifold it's probably originally for a 351C

Apr 6, 2007 | 02:34 PM

cowboyty

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its a dual plain intake with the oval holes and there is about a inch and half gap between the plate for the valley pan and the bottom of the intake. I had to put a spacer on it to get the carb to fit. I will try to get some photos this weekend.

Apr 6, 2007 | 02:39 PM

53fatfndr

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From: Earth

Quote:

Originally Posted by cowboyty

Can you pull any numbers off of the intake?

Apr 6, 2007 | 02:41 PM

cowboyty

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I will get them this weekend.

Apr 9, 2007 | 11:18 AM

cowboyty

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The only number I can find on it is 360. It has 360 on the top side on the front and rear of the intake. I haven't gotten photos yet, but hopefully in next day or so.