Doug Hampton

Attention Head and Cam swap gurus!

I recently installed a cam, heads and headers in my 2002 Camaro SS. Upon start up I heard the typical new lifter start up noise I am accustomed to when using new lifters(LS7). After running it for a few minutes of running at 1500 rpms the majority of the noise subsided and I just let it idle while I topped of the various fluids and checked for leaks and it sounded pretty good. On my first test drive I was really alarmed at the perceived valve train noise from around 1800-2500 rpm just taking it easy driving around my neighborhood, if it was an sbc I would have been sure the valves were loose.

Anyway, I had installed the push-rods recommended to me by the by the camshaft provider without first measuring for proper push rod length which in hind sight was a mistake. I realize now I should have measured and then ordered push rods. After doing some research and buying a Comp Cams push rod checker I only pulled the driver side valve cover and checked the #1 cylinder at tdc and came up with 9.5 turns. If you feel like double checking the math I would appreciate it but I came up with 7.275" at zero lash and had 7.375 push rods installed. After doing more research .100 pre-load appeared to be too much. I opted for a 7.350" push rod for .075" pre-load as that appeared to be within spec. My new push rods arrive and I pull apart the other side to find I get 9.75 turns out of my trusty new push rod checker which puts me at .0625 pre-load on passenger side bank with 7.350 push rods. I say screw it and put it together as they both appear to be within spec now.

So now I have 7.350" push rods installed with .063 on the passenger side bank and .075 on the driver side bank and it still sounds like shiesse to me... Is it worth pulling the driver side back off and dropping to 7.325 for .050 pre-load or am I just stuck with the worst sounding engine I have put together?

Would a set of ultralight yella terra rockers quiet this pig down?

I have not had it tuned yet but it seems to run pretty strong without really hammering it. This car is my daily driver and I am not sure I can tolerate this amount of noise.

Any advice would be greatly appreciated at this point.

Regards,

Doug

vettenuts

iTrader: (4)

Are they tapping (like a loose rocker) or is it valve closure noise. How aggressive is the cam you installed?

MuhThugga

This is why I hate the bolt turn method.

Being at TDC does not ensure that you are on the base circle of the cam. At this point, I prefer a method called "Exhaust Opening/Intake Closing," or EO/IC for short. What this method entails is to turn the motor by hand and watch the exhaust rocker of your cylinder of choice. When it begins to open the valve, stop turning the engine, and you are now on the base circle of the intake lobe for that cylinder. Install your pushrod length checker, and find zero lash at 22 lb/ft of torque, which is when the tool is snugged up to the rocker, there is no play in the rocker, and the tool hasn't begun to compress the lifter. Once zero lash is found, take the tool out and use a set of 8" calipers to measure its length. Take that measurement, add your desired preload, and you have the length of the pushrod you need.

On a side note, wrap the threads of the checker tool in teflon tape. It helps prevent the thing from spinning so easily when you are removing it.

Doug Hampton

Hi guys,

Thanks for the responses. The cam is 220/224 .604/.604 114+4. Could the Cam having 4 degrees of advance cause me to be that far off of the base circle? When I checked at TDC I was watching the piston with a bore scope so I have zero doubt that I was not at top dead center. When I had the checker installed I only snugged the rocker arm bolts, I did not fully torque them to 22 ft lbs. I may try and attach a short video of my noise...

Until then,

Doug

Doug Hampton

Well Vettenuts it sounds like loose rockers if we were talking about an sbc... The cam is from EPS and supposedly has the super quiet endurance lobes. 220/226 .604/.604.

I pulled off the driver side rocker cover and measured again on 2 intake valves and an exhaust valve using the EO/IC Method and came up with the same 9.5 turns with the Comp Cams push rod checker(the teflon tape helped a lot Thanks for that). 9.5 turns X .050"=0.475". 0.475"+6.8"=7.275". My first push rods were 7.375" or .100" preload which I thought were noisy and never drove it more than around the block a couple of times. I dropped to a 7.350 push rod to reduce the pre-load to .075 and it still sounds like dog s**t after driving it about 150 miles... By the way, the pass side took 9.75 turns of the push rod to take get to zero lash so passenger side is at 0.0625" of pre-load, feel free to check my math. Perhaps I should have driven it more with the 7.375" push rods?

I have been on a list for about 3 weeks to get the thing tuned by the local guy and I guess I will have them give it a listen and see what they say. If they don't have any suggestions I will probably drive the crap out of it until something comes flying out the side and then I will know for sure what the hell is wrong with it.

Any suggestions about LS7 lifter preload would be greatly appreciated...

With 7.350 push rods on the driver side I would have .075 Pre-load and if I were to reinstall the 7.375 push rods they would have .0875 pre-load. Would that be within reason?

Again I appreciate your thoughts on my debacle...

Best regards,

Doug

G8One2

Are you using lightweight checking springs when your measuring?

Doug Hampton

I am checking with 1.3" trick flow dual springs installed installed in the car. Seat pressure is set at 150#, open is 380#. Installed height is at 1.775".

Heads were milled .020" and have Ferrea 2.04" and 1.575" valves.

G8One2

You should probably use checking springs, because the regular valve springs can cause the checking tool to deflect. Also your lifters will bleed down as your taking measurements, possibly giving you false readings.

jayyk31

iTrader: (2)

Like "g8one2" said, after turning over your crank the lifters will compress & bleed off. When i adjust my valves I wait about 1-2 mins b4 I adjust each valve that is on the cam base circle, after turning over the crank. This way the lifter pumps back up.

Doug Hampton

I appreciate the input guys...

I had to walk away for a minute due to my current level of frustration.

I decided to pull the passenger side VC and take another crack at measuring with the push rod length tool. Again using the exhaust opening/intake closing method of finding the base circle of the valve I was checking I came up with yet again another measurement(someone please shoot me!).

I came up with 10 turns of the push rod checker which works out 7.3" zero lash on the #2 cylinder intake and exhaust valves and the #6 intake. 7.350" push rods were already installed on both banks and I had a set of 7.375 on the bench so I put those back in it using the bolt turn method in an attempt confirm I was in the ball park. From Zero lash to 22 ft lbs netted me less than 1 1/4 turns from zero lash to 22 ft lbs which works out about .053"(???) preload which does not add up to my push rod measurement method, it is short about .025.

I love this car and can feel the potential its going to have but at this point my fix for this effen noise is going to be a road flare and a gallon of gas!

I understand the purpose of checking springs and I know what a pumped up lifter and bled off lifter feel like. I have been adjusting valves in small block Chevy's for 30 years. For all I love about this engine the frustration I am dealing with has me yearning to work anything else but this ill conceived valve train.

My heads are milled .020, cam has .604 lift so it should have a smaller base circle by about the same .020 so that should be a wash. Valve stem heights are 1.775 vs. 1.80 stock. Stock head gasket thickness.

I almost have myself convinced that even 7.375's are too short based upon the bolt turn method, the head milling, base circle, valve stem height and how bad it sounds to me.

Now where is that road flare...