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| Mac Winter 76XB351GS |
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Gday,
I have a dead head gasket and im using it as an excuse to get better heads and maybe a mild cam while im at it. Im going to look at some 4V heads that are supposedly new and have been freshly done up with a P&P, HO valves, double coil springs, unleaded and some other stuff. I currently run 2V's on my 351. Just wondering what I will need to change to run 4Vs if I get them and what gains I can expect. Thanks
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| MikGan |
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I'd keep the 2V's, get some 4V valves in there.
_________________ I couldnt fix your brakes so I made your horn louder
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| Mac Winter 76XB351GS |
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Thats sounds like a bit of work. Roughly how much should that cost? Im not planning on spending more than $1200 on the heads. The 4Vs I am looking at are $950.
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| Walker |
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They'll bolt straight on, but you'll need 4V intake manifold and extractors to benefit from them, they'll cost as much if not more than the heads.
I'd only go 4V if you're looking at a much bigger cam than mild, and also at least 3.5 rear end gears, they lag low end power compared to 2V. |
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| black02vct |
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Age: 51 Posts: 9 Joined: 19th Nov 2004 Ride: AU Fairlane, lowered, BA XR whee Location: underwood |
How much work has your motor got?
If your motor is only mildly modified then you may find these heads won;t do much for your car as they are designed to flow more air into and out of your engine at high rpm levels 6000+ If your motor only goes to 6500 or less then you are much better off using a 2V closed chamber head with 4V valves in it with a port and polish The benefit of the closed chamber head over the open chamber is that it will slightly bump your compression up without need for changing pistons, saying this also if your motor is using closed chamber heads at moment then the 4V heads you are referring to will lose you power as they are open chambers and will drop your compression At the end of the day it all comes down to your motor and what you want out of it If relatively standard i would steer away from 4V heads
_________________ 99 AU Fairlane V8, lowered, BA GT wheels, Black TL50 replica
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| brenx |
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get some tongues in the 4v's and you'll have the lowend of 2V's. Only use the tongues in the inlets. While your there? Remove the bump from the exhaust port if it's still there. You will need a 4V manifold. I suggest a strip dominator.
Don't waste your time with the 2V's.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| MikGan |
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I think 2V's certianly have their place, you are right a set of 4V's will allow you that usability up top.. if you ever get there and set of tounges will get you some of what the 2V's have but not 100% 2V bottom end. 2'vCC heads have the compression ratio factor on their side to, something that I think is important when looking to run richer fuels. In the end its horses for cources.
_________________ I couldnt fix your brakes so I made your horn louder
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| brenx |
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You can get closed chamber 4V's too. They have the same chamber size as the 2V's
_________________ XB Fairmont sedan 11.07@123.02mph |
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| Walker |
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{USERNAME} wrote: You can get closed chamber 4V's too. They have the same chamber size as the 2V's
No they don't, they are larger in the chamber than the 2V 302 heads. I'm a fan of 2V if done right, especially for the street. You're right about the Strip Dominator, but try and find one for a 4V, they were rare as rocking horse s**t 12 odd years ago, and back then were pulling $900 second hand. I think we're all getting ahead of ourselves lol, Mac is on a budget and doesn't want to spend much so he's trying to get the best value for money. |
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| brenx |
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So how did XY GT HO's end up with 11:1 compression
4V's come in open chamber and closed. Just the same as 2V's. Technically the 4V CC is slightly bigger due to the larger valves needing deshrouding.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| Mac Winter 76XB351GS |
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Ok thanks for the input but I took a look at the heads today and they ate NOT 4V, they are 2V. Which I was actually hoping for because I dont want to buy a new intake manifold and exhaust.
These heads are mickey mouse, never been on a car, new hardened valves (Black, cant remember the brand), seated for unleaded, HO guides, new double compression springs for upto 600thou lift and new rockers. They have not been ported and polished but I got a quote from a bloke there that has been doing Clevos since the 60s for $600 for the usual tidy up and opening up of the valve throats. The total package ready to bolt on is going to be 1600 which I think is a pretty good deal for having everything new. Im 75% sure im going to drop in a mild cam while the engine is half apart. I am after a crow cam with a little bit of lope on idle and lower to midrange power, not concerned with above 5000. Anyone had any experiance with something like this? What do you think about this package now that I have a bit more info?
_________________ 76XBGS, 383c, custom crow cam, 4V p&p heads, Isky SS Valve+springs, extractors, 2.5"twins, MSD Ignition, Edelbrock intake, Forged bottom end, Barry Grant 750DP, thermo, discs, toploader, Holley fuel pump, SUPERCHARGED! |
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| brenx |
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I'd be 100% set on the 4V's
For the $ the deal sounds good.
_________________ XB Fairmont sedan 11.07@123.02mph |
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| Walker |
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Just looking at the pics (Regardless of unshrouding for valves) the size is bigger and shape is different. I see the 2V has been pluged for a Boss setup.
I used to have the CC's memorised but that was a long time ago. If it serves me correctly, the 4V closed were around 68, the 2V closed were 63, the 2V open were 76 cc. To be honest Mac, they sound a bit on the exy side for what you can buy if you look around. And saying things like HO guides is just pissing in your pocket, they sound like a basic pair of 2V heads done for gas with the usual bronze guides and a set of springs. I'm actually owed a pair of closed 4V's from a mate but i've been waiting for years, i will get em eventually but he's just a slack a***. |
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| raiki |
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2V and Australian 4V were 72.2-75.2cc open chamber (9.1:1 comp)
Imported 4V were 64.6-67.6cc closed chamber (11:1 compression)
_________________ Adrian
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| balizticbobo |
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Dont forget the factory poptop forgies
_________________ 13.28@103.73mph |
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