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| josh.c |
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Hey everyone,
my father in law has an XD 351 Cleveland Ute which he expects to have a burn valve on number 2. question is, when they say a 2v v8 clevo and a 4v v8 clevo, what does this mean? not sure if the v means valve or venturi (whatever that is). also how does effect the rebuild? different gaskets? any info much appreciated. Josh |
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| MikGan |
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heres a good article on the differences {DESCRIPTION}
I've cut a few little bits and pieces out to save you reading the whole thing, although its a VERY good read. "351C engines were produced in standard "2V" and several distinct "4V" versions, where the numbers 2 and 4 indicate the number of venturis of the engine's associated carburetor. A 2V engine is one that came with a 2-barrel carburetor, while a 4V engine is one of a variety of 351C engines that came with a 4-barrel carburetor. ... The heads are so different that they require 4V/2V-specific intake, exhaust manifolds and associated gaskets. ... 4V 351C heads have enormous intake & exhaust ports that mate to radically different, 4V style intake and exhaust manifold flanges. From within the engine compartment, 4V heads don't appear dramatically different from 2V heads, though with a few pointers they are easily distinguished. But take the intake manifold off, and you'll be stunned by the size of the intake ports."
_________________ I couldnt fix your brakes so I made your horn louder
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| josh.c |
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thankyou for that info, very helpful. if im lucky i will be able to find out the info from the vin. thanks again.
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| MikGan |
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Hey hey 1000 posts and it was actually something useful for once! swoit!
_________________ I couldnt fix your brakes so I made your horn louder
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| brenx |
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XD's only ever had 2V engines. The only thing that may have varied is the carb and manifold. 2brl or 4brl. The last 4V engines were in XB's in 1973. I don't think any 74 model's got 4V heads.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| vik351 |
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Dont they say 4V's headr are only good for fanging down Conrod straight???
vik...too thirsty for a street car 
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| brenx |
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Nah, they say that because some idiot started a myth that 4V heads have no low down power which is BS. 4V's are a factory performance head. 2V's aren't.
To expand on my earlier comment. XD 302's had 2V closed chamber heads and 9.2:1 compression. XD 351's had 2V open chamber heads and 8.9:1 compression.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| vik351 |
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{USERNAME} wrote: Nah, they say that because some idiot started a myth that 4V heads have no low down power which is BS. 4V's are a factory performance head. 2V's aren't.
To expand on my earlier comment. XD 302's had 2V closed chamber heads and 9.2:1 compression. XD 351's had 2V open chamber heads and 8.9:1 compression. If only you knew who to believe  Opinions are ares holes
vik...and there are plenty around
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| XR9UTE |
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Sorry but it ain't no myth.....The fact is, compared to a 2V a 4V doesn't produce enough low rpm torque. It's simply that the 4V port is too big to make any serious low lift flow and port velocity. When the 4V was designed in the 60's it was a case of "big is better" but these days of course we know this is not the case.
Pete. |
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| brenx |
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Pete,
I've seen plenty a 4V combo with low down power. Even ones with small hyd cams. I've spent plenty of time in the workshop that dyno tunes my car over the years. I've seen 4V engines in XW/XY/XA's go though none what I'd consider wild. To give you some idea 3.23 or 3.5 geared cars with stock - 2500rpm stalls. I've seen anywhere from 160-230rwkw on stock 4V's making power to a lazy 5500-6000rpm max. 4V's if the setups right do quite well. The ones that can't get the low down power happening with 4V's generally have no idea. they keep sticking camshafts designed for 2V heads in 4V engines which have no chance of working as they should.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| XR9UTE |
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I understand what you are saying Brenx. I too have seen many 4V's that go well but none can match the 2V combos I have worked on.
While the 4V's are starting to wind up the 2V engined cars have walked away. The only 4V that went better than a 2V in my experience was one that had port tongues fitted. BTW it's no accident that our CHI heads have smaller ports than a 4V yet piss all over them. Pete. |
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| vik351 |
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{USERNAME} wrote: Sorry but it ain't no myth.....The fact is, compared to a 2V a 4V doesn't produce enough low rpm torque. It's simply that the 4V port is too big to make any serious low lift flow and port velocity. When the 4V was designed in the 60's it was a case of "big is better" but these days of course we know this is not the case.
Pete. I thank thee for clearing that up... vik...bigger aint always better...
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| Walker |
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I totally agree with Pete on this one.
The quickest NA Clevo i've seen was a 2V. |
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| GTBob |
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This also applies to carburation as a well setup 750cfm can be better than an 850 or bigger carburettor unless you are running to 8000 RPM or above
 at which time the 4V heads come into their own 
_________________ Rotten Old Revhead!!! XW GTHO + EF ex cop car (exractors 2.5 cat back zorst !6" Simmons K&N +airbox mods Lowered with Bilstein shocks+Whiteline Bars NEXT THING Swap HO for GTP or Ferrari! |
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