afr 205's on stock 302
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Depending on the excat combo, and if its a street car I would go 205's and keep the port velocity up.
jwzg
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With the right cam, almost anything will work.
I'm not suggesting you spend a bundle on a custom cam to install a set of grossly oversized heads (for a 302) rather than save your money and build a proper stroker that could use these, but anything is possible...just not expedient.
I'm not suggesting you spend a bundle on a custom cam to install a set of grossly oversized heads (for a 302) rather than save your money and build a proper stroker that could use these, but anything is possible...just not expedient.
Wallzy
New Member
Cam's do not control the average port velocity, one of the key factors for choosing the port diameter of your head. With fuel injection cars it is not as bad since the fuel will not "fall" out of the charge, but it will not run "ideal" either. Good luck!
Walz
jwzg
Member
True, it wouldn't be optimal, but it's within the realm of possibility
. I'd personally rather have a set of 165's, but for $800, those would make for a great trade.
95Vert383AOD
15 Year Member
<~~~has heads that flow like 170's that i need to get rid of.....and i need 205's bad because my car stops making Power after 4500ish RPM 383 Strokers don't like Heads that only flow 270 Cfm @ .600
Im willing to make a deal and the creator of this tread some $$$ on top of the heads i have for the 205's
~Chris
Im willing to make a deal and the creator of this tread some $$$ on top of the heads i have for the 205's
~Chris
joel5.0
New Member
... Was the cam huge?..... in alphabet cams terms and duration @.050" wise, the intake was smaller than an E-303, the exhaust = a B/X- 303, and the LSA = F-303.
If the intake valves are bigger than a 1.94 then you're SOL unless you notch the pistons, and then you're still limited on valve lift.
Me personally, i'd run'em even if they are too big. But, i'm the type that buys things piece by piece while i work towards the big picture. Right now i've got too much cam and not enough heads...but i'll get heads down the road to match the cam and things will get better. I don't think it'll be a total pig like everyone else, but it definitely won't show you even a hint of the heads' true potential.
Me personally, i'd run'em even if they are too big. But, i'm the type that buys things piece by piece while i work towards the big picture. Right now i've got too much cam and not enough heads...but i'll get heads down the road to match the cam and things will get better. I don't think it'll be a total pig like everyone else, but it definitely won't show you even a hint of the heads' true potential.
joel5.0
New Member
Why would it be limited in valve lift? If the valve springs and valve train is set correctly, and .600" lift is required (as an example), notching the pistons has no effect on total valve lift.
Wallzy
New Member
I wouldn't say that there are cams per runner volume, runner volumes are used as a basis for determining the average diameter of the port - gives a good basis when looking at different shaped ports.
Correct, camshaft events can not affect the A/F charge.
Your car sounds like a good ride, i am in no means saying that you can not make a 205cc head work - i'm not really a letter cam guy either (even though i have one in my car) so i would have to look up the duration and LC. What i was trying to imply is that port velocity is ideal and usually designed around 300ft/s (for max power) - some institutes claim 280 and others 320, but 300 is a good basis. Camshafts duration on the other hand for the desired RPM, LC for the power band width, and lift based on the curtain area of the valve and port efficiency. These factors are usually always a good starting point when beginning an engine design from the ground up.
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Walz
Wallzy
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joel5.0
New Member
Wallzy
New Member
joel5.0
New Member
I guess you missed the whole point........
.... or let me rephrase, if the piston and valves clear, whether you have to notch or not.... Why would it be limited in valve lift?
Wallzy
New Member
jwzg
Member
Peak lift does not determine p-v clearance. The timing of the valve events does. (Captain Obvious to the rescue here) A custom cam allows you to "optimize" the setup (i.e. get it to run as good as it can). However, if I have to run less than optimal cam specs from a performance standpoint just to get around smacking the valves, that just doesn't make a whole lotta sense unless you simply want to run something different.
With that large of a cylinder head, one will likely need a band-aid to get it to the desired performance.
Some use small intakes on a large cylinder head, or a small camshaft to limit the time (and the when) air can travel into the cylinder.
A matched combination is best.
Some use small intakes on a large cylinder head, or a small camshaft to limit the time (and the when) air can travel into the cylinder.
A matched combination is best.
the cylinder heads make the power. more air and fuel in = more power. the displacement just determines the rpm where the power will be made. saying that an AFR 205 is too big for a 302 is a blanket statement and one that may or may not be true depending on the users desired powerband. i dont know that i would go so far to say that a "smaller head" would be faster because it has a more agressive cam. anyone claiming that a milder cam is a bandaid for a bigger head doesnt fully understand valve timing or cross section and its implications. Judson Massingill runs the school of automotive machinists and for a price will explain these concepts.
The total intake trac makes power, not just the cylinder head. You are missing ~50-75% of the runners, in just considering the cylinder head.
More air does equal more power, if actually used.
The top-end can also determine where the power will be made.
This is true, but let's be honest. How many guys are on stangnet with 8,000 RPM goals?
Why not? Do you believe that in every case that a large cylinder head/small camshaft is the best case scenario in all scenarios?
Who said, a mild camshaft? I hope you are not just comparing .050" numbers or lift numbers. This is a fraction of the importance. It is the lobe that determines the mildness. But then again, what is "mild."?
Do you? Does anybody FULLY understand?
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