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Author
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Topic: 2V or 4V...that is the question
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: OCT 99
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posted 01-25-2000 11:58 PM
 
On my 351C I have a set of 4V heads but Im considering going with the 2V heads and a 4v intake to make the car more streetable. I can probably sell the 4v heads for a good price anyways.
Other than the qeustion of should i do this....if i did go to 2v heads would i have to cam it differently? what would i be looking at as far as a decrease in HP and torque?
also what are the advantages of each?
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Scott (69Mach)
Gearhead Posts: 719
From: Walnut Creek, CA USA
Registered: JUN 99
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posted 01-26-2000 09:59 AM
Stay with the 4V heads. They'll make more hp. You give up a little torque off the line, but make up for it with higher rpm head flow. To get back some of the low end torque, you can install intake and exhaust port plates. They shrink the port size and increase port velocity. If you're bent on 2V heads, get the Australian closed chamber 2V heads. They have the smaller chambers and bigger valves of the 4V heads with 2V ports for good flow velocity. But, if it were my money, I'd stay with what you have and get your compression down to the 9.5:1 to 10:1 range so you can run pump gas. Stick in a 225/235 or 230/240 cam and you should be pretty happy. 
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mach72
Gearhead Posts: 127
From: Bixby, Ok. USA
Registered: JUN 99
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posted 01-27-2000 01:55 AM
You could build good power either way. One thing to think about is gearing. The 4V heads need low gears (3.90 or lower -higher numerically)) to really work well. The 2V heads have very good velocity and can use a much more modest gear (3.50 or so). The cam choice would change if the heads were changed. The 2V heads run out of flow at about .500" of valve lift if I remember right, whereas the 4V heads don't quit until about .650" of valve lift. The 4V head actually flows less than the 2V head until about .400" inches of valve lift. Again these figures are "to the best of my recollection". Good luck, Tom
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SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: MAY 99
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posted 01-27-2000 08:23 AM
The 4V heads are for high rpm use. They are best between 3000-8000. To use their full potential you'll need low gears {in the 4s, for sure} because if the motor is kept in the upper rpm range the low speed port velocity isn't a problem.But these heads aren't 2000 rpm cruising heads. Speaking as someone who has ran 4V heads since 1979, I'd go for the 2V heads {which are still great heads!} for a street cruiser.
I built a 2V Cleveland for a '86 F-150 I used to have and it was a great motor. It had 3.08 gears and it was an awesome highway cruiser. It humiliated a lot of cars, especially in the winter when I ran stock wheels with bottle-cap wheelcovers! {By the way, I ran an Edelbrook 600/AFB and I loved it.} Of course, I've heard a lot of good things about those port plates, and I plan on trying out a set sometime. ------------------
SteveLaRiviere/Administrator Mustangsandmore.com Cherishing the Past,
While Racing into the Future!
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Alex
Gearhead Posts: 148
From: Melbourne, Vic, Australia
Registered: JUN 99
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posted 01-27-2000 08:54 PM
Sorry Scott, Aussie 2V heads definately came with standard 2V sized valves regardless of whether they were open or closed chamber. Of course they readily accept the bigger valves with some machining.The 2V closed chamber head (with 4V valves fitted) was very popular here until about 5 years ago when our fuel octane dropped to the point that you can barely fuel a 9.5:1 motor. 2V heads with mild porting and 4V exhaust valves seem to be the trend here at the moment (for street and street/strip) and can give 470 hp (7000 rpm limit) and high tens with appropriate gears & converter etc. Of course many Cleveland owners realise the full potential of the motor and use 4V heads and considerably more rpms (wow!). You don't say how many rpms you are using? Another possibility would be to try a Performer 4V manifold, which has a good reputation for helping the bottom end of 4V motors. Has anyone ever tried this manifold on 2V heads??? I have one at home to try on my Cleveland, but haven't got around to it yet (C4 still isn't happy). Wulfgar, if you do try swapping the heads please let us all know how it goes, this is really usefull feedback!
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: OCT 99
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posted 01-28-2000 12:36 AM
Well, Ive decided to go with the 2V heads in my mustang to make it more streetable...its going to be a daily commuter and there really isnt much need for such high RPM's that the 4V's offer
Ill save those heads and put them on my Boss block and stick it in a pantera or something...make a cool trailer queen..=)one question...the heads are n the shop...shouild i have work done to make it so i run $v exhuast valves? would that help? if it will ill call the man doing them and tell him to hook me up
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SteveLaRiviere
Administrator Posts: 42139
From: Saco, Maine
Registered: MAY 99
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posted 01-28-2000 08:25 AM
It will help, because the weak spot of most Fords, and especially the Cleveland, is the exhaust port.Make sure he opens up the transition area and cleans up the bowl to get the most advantage of the larger valves. Also, make sure to use good quality one-piece, single groove keeper, stainless steel valves. Definately worth the money. {essential, actually} ------------------
SteveLaRiviere/Administrator Mustangsandmore.com Cherishing the Past,
While Racing into the Future!
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Wulfgar
Gearhead Posts: 193
From: SAn diego, CA, USA
Registered: OCT 99
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posted 01-30-2000 03:00 AM
Ok, I called the machineshop guy I have doing my head work and asked him if i could get the exhaust milled to accept 4V exhaust valves and he said he didnt think it was possible. Is that right?
Is there any other way I can increase the effieciency of the exhaust?
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Alex
Gearhead Posts: 148
From: Melbourne, Vic, Australia
Registered: JUN 99
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posted 01-30-2000 08:12 PM
Wulfgar,Sounds like maybe you should try another shop? putting 4V valves into 2V heads is the sort of thing I would expect any resonable cylinder head shop to be able to do - are they Ford specialists?. Steve is right, if you are changing valves, good quality single groove valves and keepers are a must for the Clever lever. Also, Steve's comments about porting etc are good ones. Make sure the shop machines the short turn radius under the valve and opens the port up 'till the seat contact is right at the outer edge of the valve for better flow. Fitting 4V intake valves to 2V heads is a litte more difficult, basically because the valve tends to get shrouded by the combustion chamber, and so the chamber needs some grinding - leading to gasket problems if the job isn't done properly. I can't remember exactly what specs your motor are? Ignition timing and cam may also be causing bottom end torque problems? What is your stall speed? Other possibilities for increasing exhaust flow are: split pattern cam (most are anyway), port plates, and all the usual exhaust stuff like headers, big bore pipes, and free flow mufflers. You probably have most of those anyway?
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Moneymaker
Administrator Posts: 25052
From: Lyons, IL, USA
Registered: MAY 99
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posted 01-31-2000 12:54 AM
I agree wholeheartedly with Steve! For the usage that you have intentions towards, the 2V heads are far and away a better choice. Also the 4V heads are much sought after by NHRA/IHRA class racers.  Alex------------------
Alex Denysenko Co-Administrator and Moderator
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TomP
Gearhead Posts: 5626
From: Delta BC Canada
Registered: DEC 99
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posted 01-31-2000 04:44 AM
Alex...(the OZ one not the US one) i have used a Edelbrock F351-4V intake (same as Performer4V) on 2V heads,not too much port mismatch,i matched them anyways. worked great,but i had not tried any others to compare it with.
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Alex
Gearhead Posts: 148
From: Melbourne, Vic, Australia
Registered: JUN 99
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posted 01-31-2000 08:01 PM
Tom -thanks for the feedback! Glad to hear that it fits OK! I have the 2V performer and a Weiand 2V accellerator. The performer is better at low rpm and the Weiand at higher rpm. I'm hoping that a 4V performer will be a good compromise for my combination. Will let you know how it goes....
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