351 Camshaft questions
12-24-2006, 04:15 PM
#1
2nd Gear Member
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Join Date: Mar 2006
Location: Warwick, RI
Posts: 289
351 Camshaft questions
Hey guys, I scored a 351W the other day for freeeee. And I'm gonna start the build in the next few weeks, but i'm a little weary on how much lift I can run without having to notch the pistons. I'm gonna be running Ported 351 Heads w/ a 1.90 Intake valve, and 1.6 Rockers.
If it comes to it, I'll get the pistons notched. But I'm really hoping to avoid that, as I've heard it gets expensive and sometime requires balancing. Furthermore, if any of you have any suggestions as what cam to get, please drop me a part number or a link.
And also, a little off topic, but in the next few weeks i'm going to be selling BBK Long tubes, BBK shortie H, Edelbrock RPM manifold and afew other things.
If it comes to it, I'll get the pistons notched. But I'm really hoping to avoid that, as I've heard it gets expensive and sometime requires balancing. Furthermore, if any of you have any suggestions as what cam to get, please drop me a part number or a link.
And also, a little off topic, but in the next few weeks i'm going to be selling BBK Long tubes, BBK shortie H, Edelbrock RPM manifold and afew other things.
12-24-2006, 08:00 PM
#3
4th Gear Member
Join Date: Feb 2006
Location: South Jersey
Posts: 1,250
RE: 351 Camshaft questions
well if you are rebuilding the engine anyways or buying new pistons you are going to have to have them balanced so just notch them and then balance....thats what i plan to do when i get my project started next fall but I could have sworn that get the piston notched wast expensive
12-26-2006, 12:44 AM
#4
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Join Date: Jun 2006
Location: texas
Posts: 1,082
RE: 351 Camshaft questions
lol duration is just how long the valves are open thats all ..the lift is how far down ya valve goes..ask ant machine shop...not a shade tree mech.. when ya ask a pro thay ask how much lift ya have not duration..i recommend doin a ptv clearence check.. use clay,play do and set heads down tighten a lil not much and set rockers,push rods,turn crank afew fullrevolutions by hand not starter,and take apart,and you can slice it,and use a feeler gauge even,ya need at leasssssssst 0.080 thousand-100thousands of a inch...some with exp can get less clearence,but a novice id say stick to reliable readings...most after market pistons have notches(valve reliefs anyway//i have kb hypers,and they came with enuff room for 202/16 valves..
12-26-2006, 12:48 AM
#5
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Location: Lil' Rhody
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RE: 351 Camshaft questions
ORIGINAL: hellas85stang
lol duration is just how long the valves are open thats all ..the lift is how far down ya valve goes..ask ant machine shop...not a shade tree mech.. when ya ask a pro thay ask how much lift ya have not duration..i recommend doin a ptv clearence check.. use clay,play do and set heads down tighten a lil not much and set rockers,push rods,turn crank afew fullrevolutions by hand not starter,and take apart,and you can slice it,and use a feeler gauge even,ya need at leasssssssst 0.080 thousand-100thousands of a inch...some with exp can get less clearence,but a novice id say stick to reliable readings...most after market pistons have notches(valve reliefs anyway//i have kb hypers,and they came with enuff room for 202/16 valves..
lol duration is just how long the valves are open thats all ..the lift is how far down ya valve goes..ask ant machine shop...not a shade tree mech.. when ya ask a pro thay ask how much lift ya have not duration..i recommend doin a ptv clearence check.. use clay,play do and set heads down tighten a lil not much and set rockers,push rods,turn crank afew fullrevolutions by hand not starter,and take apart,and you can slice it,and use a feeler gauge even,ya need at leasssssssst 0.080 thousand-100thousands of a inch...some with exp can get less clearence,but a novice id say stick to reliable readings...most after market pistons have notches(valve reliefs anyway//i have kb hypers,and they came with enuff room for 202/16 valves..
You can take a .498 lift cam and give it 300° duration, and you will need to notch the pistons for clearance... and thats NOT from lift
12-26-2006, 12:51 AM
#6
3rd Gear Member
Join Date: Apr 2006
Location:
Posts: 590
RE: 351 Camshaft questions
Your an idiot dude!
Everyone knows that maximum lift occurs when the piston is no where near TDC.
Add a bunch of duration (how long the valves are open),then there may be some clearance issues
because the piston is coming up to meet them.
Everyone knows that maximum lift occurs when the piston is no where near TDC.
Add a bunch of duration (how long the valves are open),then there may be some clearance issues
because the piston is coming up to meet them.
12-26-2006, 12:54 AM
#7
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Location: Lil' Rhody
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RE: 351 Camshaft questions
http://www.fordmuscle.com/fundamenta...ve/index.shtml
The overlap period occurs near the end of the exhaust stroke and at the beginning of the intake stroke, when both valves are open for a short period of time. Overlap is a critical period in the cam cycle, as the movement of exhaust gases out of the combustion chamber "draws" in a fresh charge through the intake valve.
Many people have even erroneously measured clearance at the point of maximum valve lift, thinking that is the most likely point at which interference would occur. However when a valve reaches its maximum lift, the piston is actually the furthest away since this occurs during the intake stroke, when the piston is moving down the cylinder bore.
The overlap period occurs near the end of the exhaust stroke and at the beginning of the intake stroke, when both valves are open for a short period of time. Overlap is a critical period in the cam cycle, as the movement of exhaust gases out of the combustion chamber "draws" in a fresh charge through the intake valve.
Many people have even erroneously measured clearance at the point of maximum valve lift, thinking that is the most likely point at which interference would occur. However when a valve reaches its maximum lift, the piston is actually the furthest away since this occurs during the intake stroke, when the piston is moving down the cylinder bore.
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