how much if using the stock cams? for the 272

 

300.00 shipped

 

Will they do a "weld and grind" so the base circle remains unaffected??
Wop

 

ok this may sound dumb but im new at this cam stuff so what kind of timing do you need to do with the 272 or 280 i mean would you have to put the chain on tooth ahead or would you keep everything as stock or wouldnt you want ajustable timing gears to get the most out of them also what need to be done to the head to run the cams.

 

Why would you not want them to touch the base circle
I'm just telling Ferrea how much material will be taken off the base circle, so they can match my valves accordingly.

 

If you take too much out of the base circle the lash adjuster will not have enouch adjustment to ride smoothly on the surface of the lobe. However, if they add weld during the process they can still alter the cam specs without grinding too much of the base circle away.

 

If you're getting custom stem length, that's fine. Problems for stock valves though as there's only about 1mm (0.039") of preload on the stock lash adjusters.Welding the lobes first allows you to change the lift profile while keeping the stock base circle, minimizing changes to the geometery.
Wop

 

I can't wait to see some hp #'s.

 

In other words, your stock lash adjusters will then be able to operate within their range. Another solution is to use modified mechanical adjusters, but it's cheaper to go ahead and get the add weld cam grind.

Blown4banger: The way you're doing it is good. Do what you do.

 

I know, I'm the master! jk I wish

 

I had the numbers but can't find them now, but I had it figured to 1/3-1/2 max of the lifter available amount of travel would be taken up.

They were noisy for the first day and have returned to stock noise levels since.

Dan is coming back into town Thursday and I'll measure his cams vs. my stockers and have exact numbers for ya.

 

i think, if i get another cobalt which im thinking about doing, someone else is doing my cams lol. but yeah that def. sounds nice dude.

 

A wider LSA will give you better idle and low speed torque. That's not the part of the power band we are concerned with here. This isn't tractors to plow with.


Here is the quote:

"Yeah, and the lobe seperation angle also determines where the power band is. The higher the seperation angle, the lower rpm the power band will be in, and vic versa. A 107.5 degree lobe seperation angle (like mine) will probably have trouble idling below 1200 rpm, and will make power into the 8000 rpm range. Thats why if you look at any cam catalog almost all the cams specified as a "street" grind, have a 110 degree or higher seperation angle."

The effect of larger and smaller LSA is on the power band what I am questioning. The upper half of the torque curve ( Y scale )defines the power band. A low LSA will produce peak torque at a lower RPM for a given camshaft specification. Torque at the top will also fall off at a lower RPM thereby giving less "top end" horsepower. This is shifting the powerband lower not higher. There is no free lunch.

I you are still having trouble understanding the concept I'd be happy to dig up a few more links for you to read.

Pierre

 

keep this in mind as well.
the c6z runs a 117 lsa.
gross lift is well over .600. at idle with the factory dump valve closed, it is very very smooth idling.

 

Yeah, the head is one of the most efficient stock heads EVER. The extremely high lift on the cam is what allows it to make power in the upper rpm, the head is what makes all the power, the cam kills power on that motor. Thats why if you look at a dyno chart of a stock LS7, it makes peak power at 6300 (because of the insanly good head) then dies, power drops steeply after 6400 rpm. Its another reason why a decent cam, and a tune yeild over 100 hp gain on the LS7.

 

I'm sorry you're wrong. If you want I can provide multiple links that say opposite of what you are saying. Or if you'd like I can show you a dyno chart to prove it.

Here i'll give you an appetizer; it's from http://www.chevyhiperformance.com/te..._lobe_phasing/:

Lower or tighter LSAs do make for a more narrow powerband and torque peaks quickly (not a lower rpm, it just peaks in a smaller range instead of over the whole RPM range) but it does not shift the powerband lower, sorry.

"The difficulty with overlap is that the results change with different engine speeds. Since race engines tend to operate in relatively narrow rpm bands (e.g., 5,000 to 7,500 rpm), it’s easier to design a cam to work in this rpm band. A street engine is a greater challenge because it must operate through a rpm band of 5,000 rpm or more (1,000 to 6,000 rpm). The key to making overlap work is maximizing the power in the rpm band where you want it. Long overlap periods work best for high-rpm power."

 

I just want to add to this ^
A longer overlap period DOES NOT MEAN A HIGHER NUMBER! The lower the LSA, the longer the overlap period.

The reason for the longer overlap period, is since both sets of valves are open at the same time, compression is lost at lower rpm, but at higher rpm since the pistons are moving so much faster, not as much compression is lost. It allows for maximum intake, and exhaust flow at high rpm.

 

Hmmm....those are very contradictory haha. Wider LSA is a higher number (Less overlap). A low LSA is more overlap.

Exactly, that's where he is confused. Higher LSA, shorter overlap; Lower LSA, longer overlap.

 

Damn! We make a good team for MAXIMUM PWNAGE!!!

 

Hahaha . When our powers combine we make.....MAXIMUM PWNAGE lol.

 

There is no stronger force IN THE UNIVERSE!!!

Ok enough nerdy showing off

 

Increase Cam Duration (i.e. How Long the Valve is Open): Moves or shifts the peak torque and peak hp location to a higher rpm. The absolute peak torque and peak hp number also increases.



Increase Cam Lift (i.e. How Much the Valve Lifts Off or Opens From Its Seat.):
Higher lift gives a higher absolute peak torque and peak hp number


Tighten Lobe Separation Angle (Increase Cam Overlap):
Gives more peak hp but less low end torque.



Lobe Separation Angle (LSA) Definition:


This is the angle between the intake and exhaust camshaft lobe peaks described in camshaft degrees. This angle dictates two important events: the valve overlap around TDC and how much intake or exhaust valve closure delay there is

Tightening the lobe separation angle (making the LSA value smaller)produces more overlap around TDC. Widening the lobe separation angle (making the LSA value bigger) results in less overlap.


Overlap Definition:

The amount of time, expressed in crankshaft degrees, that describes the window of time between the the Intake Cam's opening point BTDC and the Exhaust Cam's closing point ATDC (i.e. the brief time when both intake & exhaust valves are partially open simultaneously).


Increasing the degrees of overlap tends to move the powerband up the RPM range. Increasing the overlap can increase peak power, but only if the exhaust system is properly designed and sized to scavenge the cylinder. Decreasing the overlap tends to improve lower rpm range performance.


Overlap can be increased in 2 ways independently:

- Increasing the Duration of the Cam (without changing the LSA)
- Reducing or Tightening the LSA (without changing the Duration)



hi, send pizza

 

Good info

 

Where to?

 

laff. hmmmm, hope on papa johns.com and send me some!

it would be a long drive, and frankly the pizza would go back from AZ, to kansas city