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Looking for input regarding bigger valves in 351C 2V heads.

Will these larger valves hinder low end torque production and defeat the purpose of building with 2V heads ... or with a low lift cam could they be an advantage??

This engine will not be a high RPM screamer ... more of a daily driver & highway cruiser.

What'cha think ... any advantage here
 

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Discussion Starter #3
Morgan ... I looked at the charts ... I hate to "plead stupidity", but I'm not sure I understand what exactly they are telling me


Any chance you could edguma-cate me?

Sorry for being a dumb ****
 

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Those Aussie heads have some seriously closed chambers. They are smaller than regular 4bbl closed chambers, and shroud the valves BIG time. Unshrouding needs done with the stock valves, and installing larger valves would only aggrivate the problem.

Larger valves without the chamber work would probably HURT flow. If plenty of chamber work was in order, it might help... But, I wouldn't even consider it otherwise. The bowl will need opened up as well.

Good Luck!
 

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I have 4V valves fitted to my 351C 2V open chamber head. It has a mild cam (12mm lift) stock 4 barrel manifold, Carter Thermoquad, FMX and 2.77 diff. It has heaps of low end torque.

NOTE:
Aussie 2V heads, open chamber are 351C and closed chamber are 302C.
 

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I've talked to one Ford engine builder and read on the internet from another one that putting too large an intake valve in Aussie heads can cause flow problems. The most I've seen recommended is a 2.10 valve. I know this goes against some other discussions I've seen on the net, but I'm going to stick to what I've heard. Because of the higher port velocity in the Aussie heads, intake valves larger than 2.10 apparently create short-side radius flow disruptions when trying to blend something as large as the 2.19 size valve seat (and the area under the valve) into the short-side radius. The radius is tight enough, caused by the extremely large valve and necessary blending into the port, that flow in that part of the port the can't make the turn, breaks into the remainder of the flow, and disrupts overall efficiency.

I'm sorry if I didn't do a very good job of describing this situation. Just trying to add another perspective to your inquiry. I'm sure if anyone objects to this point of view, they'll offer their ideas.


Take a look at these two URLs, if you haven't seen them already. Lots of 335 series engine info and discussion that might keep you busy looking for several hours...

Good luck! Scott

http://www.network54.com/Hide/Forum/119419

http://www.network54.com/Hide/Forum/message?forumid=119419&messageid=1002770531
 

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Im new to this site and have couple questions for anyone who could help. Ive been fixing up a 351c with my dad for the last couple years. What looks to have happened is the cam wore out so i pulled the engine. My dad cant help me any more and since he was the one with the knowledge of everything about those engine ive had to figure it all out myself. I bought some aussie heads and put 2.19 valves, 125lbs springs, roller rockers, ported them and then assembled everything. I ran the car for about 15 min, ran bad them boom, started to run awful. I pulled it again and saw bent valves. After reading some posts i think i must of put to big a valve and also the heads have been milled as well as the deck. So i think if i didnt have the right gasket it could of brough the valves closer to the piston and also if i didnt put the right pushrods it could have caused that catastrophe. I used leaded 101 octane so i dont think it was the fuel. Should i port the heads Combustion Chamber to help with the added size of valves, compensate for the volume. PLease HELP with any links or ideas Im in a little town with one unfriendly machine shop. VEeeeery basic.
 

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????
 

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2.100/2.125 intake valve will work better for the Aussie or 2V head, short turn shape , try to get it right - will find water
 

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Looking for input regarding bigger valves in 351C 2V heads.

Will these larger valves hinder low end torque production and defeat the purpose of building with 2V heads ... or with a low lift cam could they be an advantage??

This engine will not be a high RPM screamer ... more of a daily driver & highway cruiser.

What'cha think ... any advantage here
Not recommended, even in US 2V open heads, it's better to stick with the stick diameter valve or around 2.10. The 2.19 might have a little advantage up to around 4.5 but depending on the ports the larger valves can actually hurt flow above that mark. Have the shop to a back cut on the valves to increase low lift flow. With open chamber heads, you would want to deck them to around 76~78cc and then zero deck the block because that's the only way you're going to get any kind of activity started in that big chamber. Early (70-71) 2V heads are good just about the way they are, considering they already come with a 2.08 intake and a 190cc port. The Aussie heads have a very small chamber that will put a 351C in the 11:1 compression range, so you'd have to plan accordingly. The Aussie heads are from their 302C, not a 351C - hence the small chamber.
 
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