Valve train noise ??

[itsaMustangtoo]

I know some of you guys on here are very knowledgeble on engines, so here is my question. I am getting some lifter noise on my Cobra clone after she is warmed up. I installed a Lunati cam 284 dur/ 488 lift with new springs and lifters. I used new pushrods and comp cams magnum roller rockers with the positive stop lock nuts. After she is warmed up it sounds like a solid cam !! I have pulled the valve covers-rotated the engine and all seems fine. The pushrods are 6.875" in length. I measured the old pushrods and they are the same. Could it be from the rockers ?? If so I know ford 302s also use 6.905" and 6.883" length pushrods. Should I go to a longer push rod? Lastly I am dissapointed because it almost sounds stock, I thought this cam would have a little thumpity thump.

 

[Power Surge]

I know some of you guys on here are very knowledgeble on engines, so here is my question. I am getting some lifter noise on my Cobra clone after she is warmed up. I installed a Lunati cam 284 dur/ 488 lift with new springs and lifters. I used new pushrods and comp cams magnum roller rockers with the positive stop lock nuts. After she is warmed up it sounds like a solid cam !! I have pulled the valve covers-rotated the engine and all seems fine. The pushrods are 6.875" in length. I measured the old pushrods and they are the same. Could it be from the rockers ?? If so I know ford 302s also use 6.905" and 6.883" length pushrods. Should I go to a longer push rod? Lastly I am dissapointed because it almost sounds stock, I thought this cam would have a little thumpity thump.

Before you do anything, I would suggest putting an oil pressure gauge on there and seeing what your pressure is doing. Sounds to me like you have little or no oil pressure when it warms up. Not good.

 

[itsaMustangtoo]

Before you do anything, I would suggest putting an oil pressure gauge on there and seeing what your pressure is doing. Sounds to me like you have little or no oil pressure when it warms up. Not good.

I have 40 psi warmwhile driving ( 2000 rpm)and about 25 psi in gear @ idle. I still hear it when cruising.

 

[welder4956]

Does it have stock pressed-in rocker studs? You might look at the base to see if they have pulled out of the head a little. Are the rockers tightened all the way to the stops if you have stock studs? They should be.

 

[itsaMustangtoo]

My heads do have pressed in factory studs. The guy at the machine shop that freshened them for me said I would be safe if I did not go over .500" lift. The studs are not coming out, and they are tightened to the stop ( new locknuts ) I have built 289's w/ 351 heads and used .100 thousandths over motorsport pushrods. Let me ask my question like this--- IF the valvetrain WAS adjustable and I tightened the lifter ( rocker arm ) down till it stopped tapping and went another 1/4--to-- 1/2 turn how much would this be???( .010"-.020" )??IF I use a pushrod that is .008" longer would this be enough or would the .030 longer pushrods be TOO MUCH?? The idea was I did not want to mess with an adjustable valvetrain, or I would have went with a solid cam l.

 

[cobraii351]

It could just be the rockers. I have them on my 351. They have always seemed a little noisey. I don't know if it is the roller tip or what but I've adjusted them several times and they are still a little loud.

 

[jeffnoel]

It's true roller rocker do make a little noise.

 

[itsaMustangtoo]

It's true roller rocker do make a little noise.

I will buy into that. I don't know why , I guess it just sounds good. My 460 had aluminum roller rockers but it also had a solid cam so I would not know if they were noisey or not. My 289 w/ 351 windsor heads would only allow me to take the tap away and then 1/8 to 1/4 turn more, that was it. I have seen shim kits for fords with pedestal mounts to releive them from .030-.090 thousandths . I guess for heavy head machining. SO , can anyone tell me before I pop for new pushrods ( to try ) how much preload can you put on a hydraulic lifter BEFORE it starts to hold the valve open ?? When I tightened the rocker arms down on the heel of the cam it only seemed to depress the lifter about .020" Thanks for the help.

 

[jeffnoel]

Are you adjusting them per the Comp Cams instructions? Zero lash + 1/2 turn?

http://www.compcams.com/Technical/Instructions/Files/250.pdf

 

[welder4956]

Let me ask my question like this--- IF the valvetrain WAS adjustable and I tightened the lifter ( rocker arm ) down till it stopped tapping and went another 1/4--to-- 1/2 turn how much would this be???( .010"-.020" )??

OK, if I remember right the rocker stud and nut have 3/8-24 threads. For 24 threads per inch, 1 turn is 1/24 in or 0.0417". So a 1/4 turn is about 0.0104" and 1/2 turn is 0.0208". So 0.010" to 0.020" is right.

If you used Magnum roller tip rockers with the stock studs, what keeps the tips from deflecting? Is there a "rail type" Magnum roller tip rocker arm? The stock rocker arms have rails and unless you have early style 289 heads with slotted pushrod holes or guide plates (which requires screw-in studs), you probably have valvetrain alignment issues. I have screw-in studs with adjustable rockers on mine with the Magnum rockers and have no noise problems.

 

[itsaMustangtoo]

Are you adjusting them per the Comp Cams instructions? Zero lash + 1/2 turn?

http://www.compcams.com/Technical/Instructions/Files/250.pdf

No, I am using the factory positive stop.

 

[itsaMustangtoo]

OK, if I remember right the rocker stud and nut have 3/8-24 threads. For 24 threads per inch, 1 turn is 1/24 in or 0.0417". So a 1/4 turn is about 0.0104" and 1/2 turn is 0.0208". So 0.010" to 0.020" is right.

If you used Magnum roller tip rockers with the stock studs, what keeps the tips from deflecting? Is there a "rail type" Magnum roller tip rocker arm? The stock rocker arms have rails and unless you have early style 289 heads with slotted pushrod holes or guide plates (which requires screw-in studs), you probably have valvetrain alignment issues. I have screw-in studs with adjustable rockers on mine with the Magnum rockers and have no noise problems.

I cannot believe I did not think of that (threads per inch ) THANKS , I knew someone on here would give me what I was lookin for. As for the magnum tip roller rockers they are rail type, just like the stock arms.

 

[Blue Thunder]

Non-adjustable pressed-in studs are evil.

 

[cobraii351]

Is there a "rail type" Magnum roller tip rocker arm? The stock rocker arms have rails and unless you have early style 289 heads with slotted pushrod holes or guide plates (which requires screw-in studs), you probably have valvetrain alignment issues. I have screw-in studs with adjustable rockers on mine with the Magnum rockers and have no noise problems.

Yes, Comp Cams makes a "rail" type direct replacement for the stock rail rockers. I replaced my studs though. didn't care for the press in stockers.
http://www.powerandperformancenews....uct_Code=1431-16&Category_Code=&Store_Code=CC It;s not the correct picture but you know what rockers look like.....



Tim

 

[Wart]

OK, if I remember right the rocker stud and nut have 3/8-24 threads. For 24 threads per inch, 1 turn is 1/24 in or 0.0417". So a 1/4 turn is about 0.0104" and 1/2 turn is 0.0208". So 0.010" to 0.020" is right.

SBF rockers are a Class I Lever.

The lever multiplies the distance the fulcrums moved.

 

[Wart]

Have you checked your valve lash?

Rule of thumb with hydraulic lifters is long as the plunger is mid point in it's travle it's OK.

 

[welder4956]

SBF rockers are a Class I Lever.

The lever multiplies the distance the fulcrums moved.

Good point Wart! So, if we assume the valve tip doesn't move when the rocker is tightened (i.e. the valve tip is fulcrum for tightening purposes since the hydraulic lifter spring moves), then a 1/4 turn at the stud nut would produce a 0.01625" movement at the pushrod end (2.6/1.6 = 1.625:1 ratio for pushrod movement). This would be the same result that a 0.01625" longer pushrod would produce on a non-adjustable stud.

 

[itsaMustangtoo]

Good point Wart! So, if we assume the valve tip doesn't move when the rocker is tightened (i.e. the valve tip is fulcrum for tightening purposes since the hydraulic lifter spring moves), then a 1/4 turn at the stud nut would produce a 0.01625" movement at the pushrod end (2.6/1.6 = 1.625:1 ratio for pushrod movement). This would be the same result that a 0.01625" longer pushrod would produce on a non-adjustable stud.

This is some AWESOME info. Yes I agree pressed in studs ARE EVIL , but this motor will be short lived. I am hopeing to put a stroker in next spring with some real heads on it. I am off to the auto parts to see what they have. P.A.W. catalog lists 6.876" as stock for 69-84 302's on one page and 6.905" on another. WTF.? If I do not find the pushrods I want I am going to get the tall locking style rocker arm nuts and yes, ADJUST them !! I thank everyone for the help and hope to see as many of you as I can @ the Carlisle All Ford Nats. !!

 

[78CobraII]

The '73-'76 302 block has a taller deck height than those before and after for reduced compression ratio. I don't remember the exact number, but the difference between those two pushrods sounds about right.

 

[77sleeper]

i think the number is 0.24"