Need help with OTS cam for my 331

juiced_94gt · Jan 9, 2008

Well im removing the motor to tear it apart to get to the bottom of this knock it has , well since it's coming out I might as well see if there is a better OTS cam for it, custom is out of the question because of funds right now and I don't need anymore downtime also, my current combo is: CHP 331 flat top pistons, AFR 185's, TFS stage 2 cam, TFS track heat manifold, 80mm LMAF, 70mm BBK TB, BBK longtubes, 5-speed, deleted EGR, and smog pump. Is there a better OTS cam than the TFS stage 2 or should I just stick to what I have?

PUNISHER RACING · Jan 9, 2008

how much room you have for lift?

Grn92LX · Jan 9, 2008

AFM N-71 with their valve spring kit. Custom is best choice and isn't much more expensive. You WILL need valve springs regardless.

5spd GT · Jan 9, 2008

PUNISHER RACING said:
how much room you have for lift?

Lift does not effect piston to valve clearance.

The N-71 powerband is for 2,700-6,700 RPM.

juiced_94gt · Jan 9, 2008

Grn92LX said:
AFM N-71 with their valve spring kit. Custom is best choice and isn't much more expensive. You WILL need valve springs regardless.

Sorry forgot to mention I have the PS3 spring kit from Ed Curtis

juiced_94gt · Jan 9, 2008

I dont spin the motor past 6200rpm is the n-71 alittle much?

PUNISHER RACING · Jan 9, 2008

5spd GT said:
Lift does not effect piston to valve clearance.

The N-71 powerband is for 2,700-6,700 RPM.

How do you figure if you have .120 of clearance with a .550 lift cam and you want to step up to a .650 inch solid roller I think lift would play a pretty crutial role wouldn't you?

5spd GT · Jan 9, 2008

PUNISHER RACING said:
How do you figure if you have .120 of clearance with a .550 lift cam and you want to step up to a .650 inch solid roller I think lift would play a pretty crutial role wouldn't you?

Because piston to valve clearance occurs at the period of overlap.

It is when the exhaust valve is closing and the intake valve is opening, therefore, both valves are open at the same time when the piston is at top dead center.

Peak lift occurs when the piston is a good 1.5-2.0" in the bore.

Lift is not the factor, but probably the last factor to even consider.

Why would you want the valve to open up fully when the piston is near the top of it's travel? That would be very inefficient.

You would want the peak area of flow out of the head, past the valve, when the cylinder has the most volume to fill. It would not have any volume to fill at top dead center.

A stock camshaft would hit if it had late exhaust closing and early intake opening events with a steep ramp rate.

You also want more clearance on the exhaust side for a few reasons...

Juiced - I really wish you would work another couple hours and just spring for a $325 custom camshaft. He will even do all his business through emails if need be.

I personally believe the N-71 can be beat by a custom camshaft for just a little bit more money and you could have a more useable powerband.

The fact that you have Ed's PS3 valve springs gives you an edge already.

You will see your power output increase enough to put a big smile on your face

Grn92LX · Jan 9, 2008

juiced_94gt said:
I dont spin the motor past 6200rpm is the n-71 alittle much?

The N71 will NOT go to 6,700 on a 331 with a track heat intake. I would go custom for sure knowing you have the ps3 spring kit. I used to have the ps3 springs, until one broke

Kdubslugga · Jan 9, 2008

Call Anderson or email them, usually Brian will write back he is very informative, i had many conversations with him before we both decided an Anderson b-21 cam was the best choice for what my car is. Drop him a line, but i strongly suggest Anderson, my belief is they offer the best Off the shelf cams.

5spd GT · Jan 9, 2008

A Trickflow Track Heat has more cross section than a regular street/track heat head. There would be no reason why the intake could not pull the rpm, if the heads can. We have all seen the heads do it. So why would the intake not?

My old 306 could have easily hit 6,500 if I wanted it too.

That was just a measely Performer

You could pull 7k if you wanted too, but you will not be making any progressive power there.

The N-71 is designed with 331 cubes in mind, labeled as 302-331. I would imagine Rick Anderson would label the rpm potential accordingly.

They state, "poor driveability" below 2,400 rpm.

A custom camshaft is not going to give you that issue, and I bet you will make the same power if you ask for it.

The cost between the Anderson camshaft's and FTI are fairly close. Close enough for me.

91 HATCH · Jan 9, 2008

I believe power is sacrificed for driveability in a custom cam for the street

get a comp cams 276HR

5spd GT · Jan 9, 2008

91 HATCH said:
I believe power is sacrificed for driveability in a custom cam for the street

get a comp cams 276HR

Driveability goes up if you want it, over a off the shelf camshaft. I know it did with my FTI camshaft. I daily drove it as my only vehicle for over 2.5 years...

The camshaft is tailored to your combination, not the 100s of possible combination for 302, 331, and 347 engines.

It is all what you are willing to give up.

You can get a custom camshaft with pure driveability being the factor.

Or a mix between the two, or pure race

Many people think a custom camshaft is for pure performance, but it is not.

Unfortunately, you see this on the other end of the spectrum.

Many assume since you have X parts, that you should run X time, especially when you have a "custom" camshaft tailored for what the driver wants.

just4bob50 · Jan 10, 2008

91 HATCH said:
I believe power is sacrificed for driveability in a custom cam for the street

get a comp cams 276HR

That one of the dumbest things Ive heard. If all out power was all that was needed why arent you running a TLSR camshaft and shaft mount RR's. A custom cam from some one like Ed Curtis or Jay allen will give you the most power while still being streetable. Then again the term streetable is subjective.

Need help with OTS cam for my 331

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