A buddy of mine is lookin to buy a new camshaft for his 5.8L F150. I went to the Summit website to look at camshafts, but I realized that I have no idea what I was doing. It listed the advertized duration, lift, and I have no clue as to what those things mean. I went to sites like HowStuffWorks but the explanations they give are extremly basic. Does anyone want to give me a little explanation on what all that stuff means and what types of camshafts are best for street driving, towing, racing, etc?
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88 Town Car (wrecked, for sale)
Walker OEM duals with muffler deletes -
What year truck ? EFI? Mass air? Speed desity? Goal of change?Scars are tatoos of the fearless -
It's a 94, so it's EFI. I don't know if it has Mass air or speed density. And I think he's replacing the camshaft because he likes to drag race the truck so I guess he wants a higher performance cam. I just want to know what the duration and lift stuff means, and what duration and lift is needed for dragstrip use.88 Town Car (wrecked, for sale)
Walker OEM duals with muffler deletesComment
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Got to know which its about that year it changed.Scars are tatoos of the fearlessComment
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I just called him. He says it's mass air.88 Town Car (wrecked, for sale)
Walker OEM duals with muffler deletesComment
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Go with the FMS E cam Crane makes it and is in the Crane book to 220 duration @ .050 and just under .500 lift .. .491 I think.Scars are tatoos of the fearlessComment
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Those numbers are what I was talking about when I said I don't know what they mean. For example, what does 220 duration @ .050 and under .500 lift mean? Are the numbers higher (numerically) for higher performance cams? I'm a total noob when it comes to things like this.Originally posted by turbo2256b88 Town Car (wrecked, for sale)
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Lift is the amount the cam raises the valve off the seat. There are 2 figures given for lift. Lift at the cam lobe and lift at the valve. Lift at the lobe referd to as lobe lift is the amout the cam lifts the pushrod and lifter off the base circle of the cam. Valve lift or gross lift is the amount the lobe lifts the push rod and lifter times the rocker arm ratio. Here is an example for a 460. A 460s rocker ratio is 1.73. A lobe lift of .282 times the rocker ratio 1.73 would result in lift at the valve of .488. If this lobe lift is used in an engine with 1.5 ratio rocker arms the lift would be .423
How are you doing so far?Last edited by turbo2256b; 09-04-2006, 08:29 AM.Scars are tatoos of the fearlessComment
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It's still a little confusing. What is duration and what does it mean? It's different than lift, right?88 Town Car (wrecked, for sale)
Walker OEM duals with muffler deletesComment
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duration is how long the valve stays open. long duration cams allow the cylinder to fill more completly.
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Duration is how long the "lift" occurs in degrees. The "@ .050" is...well I don't know how to explain it...basically with the valve open .05" there is no air flow so they measure starting and ending with that. Make sense? Duration would be longer if measured at 0", I suppose its more accurate at .050"...
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Duration is the amout of time a valve is open in crankshaft degrees.
Advertised duration is a bit lame because it is measured from some lift point to a closing point. Without knowing were the lift point is they begin to measuer it at your left hanging. The earlier they begin the more duration.
.050 duration is more accurate. It is realy tellling you at .050 after the ramp starts to lift the valve how long in crankshaft degrees the valve has been open. It also helps determine the power band or range of a cam and helps to compaire one cam to another. The higher the number the higher the power band. Each degree of change at .050 is equal to about a 500 RPM change. Note here that whatever you gain in a higher range you can loose that or more at a lower range.
Another note a cam needs to be matched to cylinder head or a manifolds (usally the limiting factor) air flow. If not matched correctly performance suffers. Your are usally better off with a milder cam than a hotter one.
A misconception is cams do not increase air flow. They only effect power bands.Scars are tatoos of the fearlessComment
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E cam is a good power maker, but gears and converter should be in the plans with 220 duration. 2400-6000RPM operating power range for that cam. .498 is the lift.Comment
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does the truck 351 use the ho firing order?
1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
2006 Lincoln Town Car Signature. Stock for now
1989 Ford F-250 4x4 much much more to come, sefi converted so far.
1986 Toyota pickup with LSC wheels and 225/60/16 tires.
2008 Hyundai Elantra future Revcon toad
1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)
please be patient, rebuilding an empire!
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The "HO" firing order is actually the 351W firing order. Early HO motors used 351W cams from the early 70's.
All 302's and 351's from 1994 on used the same roller cam with the exception of the Lightning 351W which used a flat tappet marine cam from the 70's.Comment
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