4v intake
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New User
Joined: Jan 2003
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4v intake
Are 2V heads good for any kind of set up with the 400M? I hate to buy 4V's. I have two sets of 2V's just laying around. I have noticed the 2V exhaust with 1.71" valves supposedly out flows the 4V. I think open chambers works well with pop-up pistons don't they?
"D"
"D"
Senior User
Joined: Jun 2002
Posts: 423
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From: Oklahoma
4v intake
2V heads don't have a quench area so most folks caution against running much over 9:1 compression with them. As far as flow, it's the typical poor flowing Ford exhaust port that's the problem; the intake side flows quite well. As far as the 2V exhaust port flowing better than the 4V port (with any size valve), that is doubtful. Port match the intake side, clean up the bowl areas, open up the exhaust side and install 2.09" (460) or 2.19" (351C-4V) intake valves and the 1.71" exhaust valves and you'll have a decent set of street heads. Using a dual-pattern cam with longer exhaust duration than intake can help balance out the port flow.
Posting Guru
Joined: Aug 2000
Posts: 2,416
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From: PacNW
4v intake
Open chamber heads are not good for quench...period. However there's no reason they can't be used to make decent power and torque. 2V heads with 4V exhaust valves do outflow the 4V heads becase of the location of the port. I'd suggest that you grind the thermactor bumps out (if there are any...my '74 2V heads had them) clean up the bowls and grind the heck out of the valve guides to help improve the flow. I've seen 2V heads with the portion of the guide that's in the pocket completely removed to help improve flow. There's plenty of metal there so don't be afraid to remove some. Definitely go with a dual pattern cam with longer duration/higher lift on the exhaust side.
Posting Guru
Joined: Aug 2000
Posts: 2,416
Likes: 4
From: PacNW
4v intake
There's really no such thing as "2V" M heads. Cleveland 2V heads and M heads are basically identical as far as valve size, cc's, and port size. There may be some differences in the exhaust ports but FoMoCo never made a 4V M.
