maximum valve lift

[import convert]

does anyone know the maximum valve lift stock heads can handle? im looking to get a cam where the intake lift is about .532' lift so i want to make sure itd work with the stock pistons or if id need to get ones with valve reliefs. and yes ill be porting the heads cause this cam is a bit radical for stock ports.

if anyone knows a safe valve to piston gap that can work too

[Outlaw440]

Dude, there are so many more factors that have to do with ptv (piston to valve) clearance than just lobe lift... Only way to find out for sure is to try it by checking yourself, unless multiple people have used an identical combo and can give you a ballpark estimate as to whether it will work or not, and even that isn't a %100 trustworthy method...

Radical cam? What's the duration on it? LSA? I've had .600 lift cams that were mild.

[import convert]

a comp cams 35-601-8 thumper cam

291 intake duration @ .541 lift
311 exhaust duration @ .526 lift
107* lobe separation

im gonna use ported E7's or D8's

and yea i know the head gasket thickness and if the heads are shaved will change all that. i know theres ways to get a clearence measurement but im not sure of the distance thats ok after torqueing the head down to get the gap

[import convert]

i was thinking a 35-600-8 too

Intake Duration at 050 inch Lift 227
Exhaust Duration at 050 inch Lift 241
Duration at 050 inch Lift 227 int./241 exh.
Advertised Intake Duration 283
Advertised Exhaust Duration 303
Advertised Duration 283 int./303 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.531 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.515 in.
Valve Lift with Factory Rocker Arm Ratio 0.531 int./0.515 exh. lift
Lobe Separation (degrees) 107

[Lazerbeans]

I ran across this info a year or two ago, and I will just quote it, easier that way. Not exactly your sitation but it brings up a few points.

"It is more of a matter of duration and not lift numbers that matter in this situation. When the valve is open, the piston is on it's way down so lift numbers aren't the problem. The duration is the length of time that the valve stays open and is where you more than likely may get into trouble. In theory, you could run a .700" lift cam and not have piston to valve problems if is has a short duration. Also, you could use a cam with only .400" lift and if the duration holds the valve open too long into the stroke you would have contact. In our experience, we have used the Trick Flow Stage 2 camshaft with numbers at .544"/.563" lift and 224/232 duration @ .050" and have no clearance problems at all on a stock shortblock. Piston to valve clearance should always be checked during assembly, but just try to not to get "hung up" with lift numbers only......there is more to it than"

Don't ask me where I got that quote because I don't remember for sure. Through it wasn't Trick Flows web site.

[import convert]

well last night i was looking around and going to comp cams and jeggs and they list a lot more info on like what the cam will work with best like gear ratio and compression ratio and manual or automatic( converter stall)

made me think about it more and what to get. now i probably wont use the thumper cams cause its a conversion cam to run hydraulic roller setup on a block that was origionally a flat tappet or somethign like that.

i knew there was more to it and theres a "rule of thumb" clearence, but yea i wasnt sure what factors go into it and i dont want to get a cam that wont work so i figured id ask.

i would like to make this thread a rough guideline for all so they can maybe see what works and what doesnt along with whats a good rpm range for each car and overall usage of the car.

ford racing gave a guideline for duration and what tll work for

duration
270-290 can give good idle and good low-end torque
use with slightly modified or stock engine and stock gear ratio with AT/MT

290-300 fair idle quality, good low to midrange HP and torque
use with slightly modified or stock engine and stock gear ratio with AT/MT

300-320 rough idle, good mid to high rpm HP and torque
use with MT or high stall AT, improve carburetion, ignition and exhaust
engine will have less vacume than stock

320-340 rough idle, good mid to high rpm HP and torque, for all out competition
use with MT or very high stall AT, improve carburetion, ignition and exhaust
engine will not have vacume for accessories, axel gear ratios must be properly seleted

[gadget73]

Mind you that almost all "this works with a stock shortblock" statements are based on Mustang HO engines, which have valve reliefs. Stock lopo pistons do not have reliefs, so you're a lot more limited.

[Outlaw440]

Mind you that almost all "this works with a stock shortblock" statements are based on Mustang HO engines, which have valve reliefs. Stock lopo pistons do not have reliefs, so you're a lot more limited.

Good point.

[import convert]

Mind you that almost all "this works with a stock shortblock" statements are based on Mustang HO engines, which have valve reliefs. Stock lopo pistons do not have reliefs, so you're a lot more limited.

i was thinking bout getting some pistons with reliefs just to be safe and to have new pistons

[gadget73]

for all that bother you may as well just find a usable HO or Explorer shortblock. THey both have relieved pistons, and Explorer motors have better heads.

[import convert]

true. i can get a set of sealed power pistons for 110 at work. but yea then pay to have them put on the rods

[import convert]

another question i had was how can you tell what cam would be more agressive if one had more duration but the other had more lift? or is more lifter better for torque and duration better for HP? i know lift is how wide the valve is opened and duration is how long its open for

[Pirate]

Stop. Just stop.


Find a low-mile Explorer GT40P motor, swap the valvesprings and locks/retainers out for some Comp Cams beehive units, and swap over your oil pan and belt-driven accessories. Get a set of Ford Motorsport shory headers, and put a good 2 1/4" dual exhaust (with H-pipe) behind it. After that, enjoy the donuts.

And after that point, leave it alone, until you can build a proper engine, and the supporting cast (transmission, rear-end, vacuum-powered accessories) can actually keep up with a low-vacuum camshaft such as the ones you are suggesting.

[import convert]

ok well i have exhaust. i have a mild build arleady. im getting a tci valve body and ill work on gears. im asking questions now so maybe i can understand cams and not get something ill hate. its not like my car is stock and its not like im just going out to buy a random cam. i want it to work and i know there are people on here that know more about cams then i do (like you pirate) so i figured id ask but instead i seem to get criticized.

[Outlaw440]

If you want something truly fitted to your combo go custom cam. But given the combination you laid out (stockish heads etc) money might be better spent upgrading the package (h/c/i) as a whole, or just toss some 1.7 rockers on an ho cam.