Hey all,

Question: I have a solid roller cam with roller rockers and stamped steel valve covers. This thing sounds like a sewing machine. Are these cams always this loud? If you put your ear by the wheel wells, it sounds like a diesel. Any comments or thoughts?

Steve

 

Haev you adjusted the rockers lately? Dod it make any difference?

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"So many Mustangs, so little time..."
ICON Motorsports

 

a lot depends on the cam profile. They do make quieter solids. Sometimes roller rockers can add a large amount of noise for two reasons. First if they are sloppy, as in excess play at the bearings. Second they often have large thick bodies that can come in contact with your spring retainers. Both conditions can be very noisy.

 

OK, valves were just adjusted. No change in noise from before to after.

They are roller rockers. But they do NOT hit the spring retainers, checked that already.

Also they do not hit the stud girdle either.

Any other suggestions?

Thanks for the replies.

Steve

 

Forgot to mention,

The cam is 242/250 @ 0.050"

Lifts are 0.657" intake/ 0.600" exhaust

Valves were set with 0.022" gap. That gap was recommended by Crane who ground the cam.

 

With that much cam, expect some amount of noise; but it shouldn't be too noticeable over the header noise.

It may be your adjustment technique. I have found only 2 really reliable ways to get them right.

One is to loosen them all a whole bunch, like ½ turn. Then carefully tighten each one that the feeler gauge will go into, to spec. Then bump the motor a slight a,ount, and go all the way around the motor, all 16, again. Than bump the motor again, and check all 16. Keep doing this until the crank has made 2 complete rotations, with at least 8 stops per rev. If you do it this way, at no time after the intial loosening shoul dyou ever loosen a rocker again, only tighten as you go. If the feeler won't go in, leave it alone.

The other way is to find the point of max lift on some valve with a dial indicator, and adjust the one exactly opposite it in the firing order. Then turn it exactly 90° and adjust the next one of the same type valve in the firing order, then the next, etc. For instance, if you were to walk up to the motor and discover that #6 intake was at exactly peak lift, then at that instant the #1 intake, which is the one 4 cylinders away in the firing order, will be at exactly minimum lift. You would adjust that valve, then turn the motor exactly 90° and adjust $8 intake, then 90° more and set the #4 intake, etc. Then go back and do all the exhausts the same way.

With that much cam, the shortcuts like setting both valves when that piston is at TDC or the like will not work. The cam will not be at its minimum lift point, so the lash will be too great.

Another thing that never works is trying to set a solid cam with the motor running.

If you are using Poly-Locks, leave them a tiny bit loose (like an easy slide of the feeler instead of a tight one), and tighten the lock screw as tight as you can get it with the Allen, then tighten the screw and the nut together with the Allen and a 5/8" box wrench a little more afterwards, to lock it more securely.

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"So many Mustangs, so little time..."
ICON Motorsports

 

rb are you as confused as i am? how does a cam come in contact with the spring retainers?

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ICON Motorsports

1st & 3rd

 

The cam wouldn't but the rockers might if the pushrods are too short... which could be a possibility with that much lift. I wuold expect to use probably .100" to .150" longer pushrods than the nominal length at that lift figure, maybe different lengths on the intake and exhaust.

BTW what ratio of rockers are these?

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"So many Mustangs, so little time..."
ICON Motorsports

 

The rocker ratios are 1.7 Comp Cams on the intake and 1.5 Crowers on the exhaust.

The engine builder who did the push rod length check told me to use +0.300" on BOTH the intake and exhaust. I was unsure of this but, I figured they knew more than I did. So that is what is in the motor now.

Should there be different lengths for the intake and exhaust?

 

FB,

Every engine is different, but the push rod length is generally determined by the cam base circle and rocker stud length/installed height. If you've changed to longer valve stems to adjust the spring installed height, you'll have to adjust the push rod lengths accordingly. This is not normally the practice, but with those lifts you might not have been able to get all of the installed height increase from spring seat machining alone.

It stands to reason that the same length push rods should be used on both the intake ans exhaust since the base circle is probably the same on all the lobes. Even the BBC with the staggered valves should probably use the same length push rods.

What is a little surprising is that Crane recommended the same clearance on both the intake ans exhaust, and that it seems so high, especially for rollerized rockers. You are adjusting the valves hot, aren't you? Or was that a cold lash specification?

You will get some valve train noise from the rollers, and more so since there is some mechanical lash. This can be quieted a bit with aluminum rocker covers, but the noise is still there.

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Later,
Vader
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"I know how to solve your problem, but I can't tell
you since you might use the information illegally..."
Adobe Acrobat Reader 4.0

 

Here's a quick rule of thumb when adjusting valves with solid lifters:

Adjust Intake when the Exhaust STARTS to open.

Adjust the Exhaust when the intake IS ABOUT to close.

The valve you're adjusting at each point will be off of it's "clearance ramp".

I learned that from some road racing buddies a long time ago and have used it on everything from Mopar-sixes to 675 HP Big-Blocks.

Prove it to yourself when you have (lotsa) time. Compare it with the TDC - 90 degree method; there will be no difference.



[This message has been edited by 88SC (edited February 10, 2001).]

[This message has been edited by 88SC (edited February 10, 2001).]

 

ede, are you questioning me?
nah you just read my post wrong.

RB83 that was some excellent advice on the lash adjustment. You are completely right.

Vader, also excellent. I will remind you that canted valve heads such as my TFS actually need different length pushrods on intake and exhaust since the intake valve is further away from the lifter. The same lengths will work but will not be optimal.

And yes that cam would be noisy anyway, but just in case I would do a leakdown check on your cylinders to rule out piston/valve contact. I have seen this happen before where the pistons simply indent and not break the valves, yet it creates a LOT of tapping noise (obviously) that is heard up top at the valve covers. Can't hurt to check,
good luck
ODB