Engine Max cam lift on 302 ho engine

[GreyMare88]

I'm finally about to start on my build; I'm looking at a lunati cam with a .522 lift and I wanted to be sure of my valve clearance and I don't want to get something that I can't run in my engine....any guidance and help is truly appreciated.

 

[Monkeybutt2000]

Need more details. What heads? Stock bottom end?

 

[jrichker]

Max lift varies with cylinder head model and machining, piston top configuration, head gasket thickness, etc.
Use soft clay to determine piston to valve clearance as shown in the attached video


View: https://www.youtube.com/watch?v=4_ZdcAE67L0

Or


View: https://www.youtube.com/watch?v=Y66lvdHbm60

 

[GreyMare88]

I'm running GT40P heads; stock bottom end.

 

[jrichker]

I'm running GT40P heads; stock bottom end.

That still doesn't take into account all the possible variables. Do the clay method or you may wish that you had...

 

[Mustang5L5]

Duration matter more than total lift. When the valve is full open, the piston is at the bottom of the cylinder.

so the entire valve event must be taken into consideration. You can go with pretty aggressive lift if the cam profile opens and shuts the valve fairly quickly.

You’ll need to post the entire cam events and have a cam guru (not I) make sense of it.

 

[GreyMare88]

This is the one I'm looking at.

 

[Rcdgl]

Absolutely a must check. The clay method is cheap and pretty quick. I would do at least two cylinders. My Gt 40 heads cleared my trw forged replacement pistons. My AFR 185s with larger valves hit.

 

[GreyMare88]

Will check into it.

 

[KRUISR]

I'm not a cam guru, but that cam looks okay for a stock 302. My Crower is a little higher lift and duration (with my 1.7 RRs) with no issues using 3-bar GT40s. I agree with others that the clay check method is best bet.

 

[GreyMare88]

I'm not a cam guru, but that cam looks okay for a stock 302. My Crower is a little higher lift and duration (with my 1.7 RRs) with no issues using 3-bar GT40s. I agree with others that the clay check method is best bet.

Which one are you running; I was told about the 15511 but someone told me it was more suitable for nitrous than a blower?

 

[KRUISR]

I have the 15512. It was stamped 222HR229 on the end of the cam.

Didn't know you were going with a blower. I'm naturally aspirated.

Attached are the cam specs of the 15511 and 15512. I printed them as pdf files from Crower's website.

 

[GreyMare88]

Cool; how is the power and torque with the 15512?

 

[KRUISR]

I have not been to a dyno and not to the track. I believe I am in the 350-370 range at the crank (right around 300+/- to the wheels - I have a mostly stock AOD, upgraded VB only). This is based on running a street 1/4 mile distance. Leaving from idle, shifting at 5500, I hit the 1/4 mile distance at 4900 rpm in 3rd. Doing the math through the drivetrain (3rd gear 1:1, 3.73 gears and 26" tall tires) that puts me at 103 mph (speedo shows 165 km/h - basically the same).

Using on-line calculator, adjusting hp and weight (my car is 3750 with me in it) to get close to that speed. I am leaving at idle and the calculators probably assume drag type launches so I am likely a little better than what they come up with.