I have a new cam that I am installing this coming weekend in my 350/300 engine. This is not the original LT1 engine. This engine came from a 69 Camaro that was parted out.

The cam is the Crane 274H06 kit to include lifters, 1.5 rockers and new pushrods. I bought the Competition Cams cam chain and sproket set. This is where my question comes from. With this set, I have the option of three positions, -4 degrees, TDC, or + 4 degrees.

My engine is stock with the exception of the Performer intake. My drive train, just for info is the stock 4 speed and 3.73 gears.

Which position should I use when reassembling and what effect would using one over the other make?

Thank you in advance for any help, I'm learning.

Christopher

 

Start off at TDC & see how it works out.
-4 will move peak power to higher RPM (top end feels better)
+4 will move peak power to lower RPM ( bottom end feel better)
Also keep in mind that depending on piston to valve clearance, moving cam timing away from straight up (TDC) may result in valves hitting the piston.

 

Thank you for the info. Assuming I have sufficient clearance, what setting would you recommend for a weekend driver, looking for say, red light to red light acceleration?

Also, would one setting have any effect on idle charactoristics over thenothers?

Christopher

 

Advancing camshaft will increase lower rpm torque, er, move the torque peak to lower rpm.
For street use, torque is the work getting you to the next stop light.


An old school tuning trick is using a compression gauge and starter and use the cam degree setting giving the most compression value.

 

Since "red light to red light" acceleration is what I am after, I will use the +4 degrees key location. This is my first solo cam installation and I want to get it right the first time.

Thanks again everyone for your replies, and Merry Christmas!

Christopher

 

One more question, remember I'm learning! Will advancing the cam 4 degrees have any effect on the idle characteristics vs using TDC?

 

Certainly will, as advancing moves the intake closing event forward in the cycle giving less time the intake valve is open during the intake cycle. Clear as mud?

Vacuum is developed with the intake valve open and piston going down in the cylinder for #X degrees. Shorten the length of degrees, referencing piston TDC, by advancing the intake lobe, gives a shorter 'time' of developing a vacuum.
Since the camshaft, as a whole, is advanced, the exhaust event is also moved/advanced.

Will you notice a difference with the vacuum gauge?
Maybe, you might see 1" less vacuum.

 

You hold a wealth of info Everette. Thank you for your time explaining all of this to me. I haventhe cam in and the chain and sprockets just arrived via UPS so I'll be hard atbit tonight. Other than the vacuum, will there be any more choppiness to the idle? Im not really crazy aboutnall the sound effects but I want to know for reference so Ill know what to expect when I fire it up. I know that cam has a slight bump to it as it is, just not sure if it will increase that. Guess it really doesn't since I have a four speed but Im not so keen on the car shaking either.

I went ahead and replaced the push rods and rockers while it was apart and although the chain and sprockets weremonly a few thousand miles old, I replaced them also with the comp cam double roller chain set.

Christopher

 

You're welcome, Good luck with the next chapter.
Let us know how it turns out.

 

The cam installation went well. No leaks, no flat lobes, the car runs awesome. Has a bit of a choppy idle but it sounds good, nothing that screams race me. I do want to ask one more question about the set up, I replaced the rockers with the stock 1.5. Now, I see where many go to 1.6 rockers. On a pretty much stock engine, the 1.5 rockers were what I wanted,mcorrect?

Thank you for all your help and info. You guys are terrific. Happy New Year! Next mod.......? Ha