AJay

iTrader: (1)

I just installed AFR heads @ 62cc and a 224.228 cam and there is a noticable "sewing machine sound" coming from the Valve Trane. My tuner told me to expect this and that it's common. My question is what exactly makes this sound. I have heard theries that it is due to incorrect geometry, spring pressure, valve closing etc.

Can someone explain exactly what's going on here. Valve wipe on this engine was checked dead on the center of the valve and push rod length was measured and confirmed correct so I don't think geometry is an issue here.

Viper

iTrader: (6)

What pushrod? What lifters? What rockers? What head gasket?

AJay

iTrader: (1)

Trick Flow Moly push rods
Rollmaster dual roller chain
Morel lifters
PRC dual springs (basic to the AFR Heads)
Stock GM Gaskets

ShevrolayZ28

iTrader: (4)

How much preload? You did know that Morels call for less than OEM style, right? Around 0.020-0.040" if a recall.

You're in luck, Mr Viper runs the Morels, he can help you out.

RoastEmSS

what size pushrods

AJay

iTrader: (1)

No idea regarding push rod size or preload. My tuner did the install.

PREDATOR-Z

Too short of a p-rod
This valvetrain noise being acceptable is a misconception (which I believed for awhile).
Improper preload does that.(too light)

cantdrv65

iTrader: (3)

My car bone stock had some sewing machine noise.... I wouldnt worry about it. It got slightly louder when I went to the PRC dual equipped LS6 heads. With more spring comes more noise. It shouldnt be ALOT louder than stock however.....

AJay

iTrader: (1)

Mine is significantly louder. Not too bad standing outside of the car with the hood up but inside the car it is very noticeable.

Going back to my original reason for this thread,,,,,, what exactly is making this noise. Is it increased spring pressure slamming the valves down harder on the seats?

Grimes

iTrader: (3)

to make up for the smaller base circle of the new cam, try a pushrod that is 0.025" longer than the one you have now.

most accurate way (since it looks like you have milled heads) is to use a pushrod length checker.

cantdrv65

iTrader: (3)

If its significantly louder see Predators post...

Even with proper predoad it WILL BE louder than stock. The ramp rates of the cam and stronger springs both contribute. You are opening and closing the valves much quicker than stock. Ask your installer where he set the preload. If it has been measured and is in spec, you are fine.

AJay

iTrader: (1)

Understand the pushrods may be too short but can someone explain (for a dummy like me) what happens in the valve trane to make this noise.

Thanks

Viper

iTrader: (6)

I wish I could say what EXACTLY causes the noise. All I can say is on my setup 7.325 pushrods were too much preload thus causing the ticking. I'm at 7.300 now ( after using a $20 pushrod checker ) with my preload around .025-.030 on the Morels and it's plenty quiet now. And FWIW, the 7.325 were put in by an engine builder! So nothing wrong with checking it yourself, or at least find out if the engine builder is aware of the required preload on the Morel lifters.

AJay

iTrader: (1)

Viper

Could I be damaging my engine by running it this way?

AJay

iTrader: (1)

Anyone??

Viper

iTrader: (6)

Now understand we are not sure you are hacing preload issues until you pull the valve covers and actually measure, BUT, once you do:

https://ls1tech.com/forums/showthrea...t=preload+tick

https://ls1tech.com/forums/showthrea...hlight=preload

Fascinating read:

https://ls1tech.com/forums/showthrea...hlight=preload

http://www.cranecams.com/?show=techarticle&id=2

eamador11

I disagree, the cam he has is a fast ramp rate cam and the sewing machine sound comes from the valves slapping shut hard. The patriot springs also add to the sound due to the stiff coil but they are strong *** springs!

AJ- Its a typical sound for all heads and cam. youll be fine

Viper

iTrader: (6)

I'd like to hear what exact pushrod his engine builder used. 62cc is .024 off the 66cc normal AFR 205 head. Granted his cam 'probably' has a smaller base circle but no guarantee. For example my cam is 227/231 but has the same base circle as stock.

PREDATOR-Z

I used to think so.

Take my new built 370, XE-R 232/234 .595/.598, Platinum PRC duals (~.660 lifts), 11.7 SCR, 8.6 DCR (high cylinder pressures).
Can't hear a peep out of the valvetrain. I use Comp 850-16 with .080 preload.
The valvetrain noise is nothing like I used to hear on earlier setups.
I started reducing noise by increasing preload closer to stock specs. The closer you get, the less noise.
Anyways this is from personal experience.

Photochop

iTrader: (74)

Every heads/cam, even most cam only cars I've heard sound like that. I thought it had to do with the stiffer valvetrain components as well.