Comp Xtreme Energy Cam and Magnum Heads

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dgc333

dgc333

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As you all have seen pictures of I built my 360 with magnum heads and I used a Comp Cams XE268H Extreme Energy cam. I also used the stock magnum rockers, MP Mangum R/T springs, the Mopar Performance push rods for the magnum conversion and Melling flat tappet lifters. I broke the cam in at 1500-2000 rpm for approximately 15 minutes.

The oil pressure runs about 3/4's up the normal range on the gauge cold idle and will drop down to about 3/8 up when hot. The only accurate number I have is when I primed the engine and got 40 psi on a guge screwed into the sender port with a drill.

My question/issue is; I have a very light tappet noise at idle. It sounds consistant across all the cylinders very much like a solid lifter cam. Is this a characteristic of the extreme energy cams or did I use the wrong lifters or is this the beginning of a problem? I have just shy of a 1000 miles on the engine and I have 10w-40 oil in it.

Oh ya! The engine runs real strong otherwise and the lifter noise does not gt worse with rpm.
 
sounds to me to be a by product of the extreme ramp speed of the cam. As they accerate the valve opening by lifting the valve faster and faster the lifter has a tendency to make a little clatter as the lobe comes around from the heel to the ramp it seems to slap the lifter thus your noise
 
Thanks for the input.

I did call Comp Cams and there thought was that I didn't have enough preload in the lifters. They suggested that I get the cam on the base circle and scribe a line on the push rod even with the valve cover rail then release the the rocker arm and scribe another line. If it's not at least 0.060" then I will need longer push rods. I forgot to ask what would be the answer if it is more than 0.060". :(
 
Agree with outlaw. Thats a prretty fast ramp speed they use. I think they all make alittle noise.
 
Ya pre load is important and will make a lot of noise if set wrong but dont be surprised if you still hear some tappet noise even when you do have the pre load right. These new fast ramps go from zero to hi lift in almost no time at all . the shock from being on the base circle to being .050 in lift is so much more extreeme and sudden then older design cams that it really puts some wear and tear on the valve train
 
FWIW, I called Comp Cam again and got a different tech. He told me pretty much the same thing that I would have some lifter noise with the XE cams.

Also, he said preload of 0.020" to 0.060" was adequate. He suggested a heavier oil than the 10w-30 I had in the engine would help some. So when I had the car on the lift at my daughters shop to install the exhaust tips I changed the oil to Shell Rotella 15w-40 heavy duty oil. It did help some.

He also suggested I make sure the push rods are not hitting the guide plates at the bottom of the slot. He said it shouldn't be a problem with the XE268H cam but there could be some tolerance issues and it's worth the check when I have the valve covers off for the preload check.
 
The first tech said minimum of 0.060" the second guy stated 0.020" to 0.060". The second guy actually seemed to know some specifics about mopars and had a list of mopar performance part numbers for things that comp didn't have (like springs, retainers and locks for the magnum heads).
 
This is a non adjustable magnum valve train. If I do not have enough pre-load I will have to either get different lenght push rods or invest in an adjustable rocker system.
 
dgc333 said:
This is a non adjustable magnum valve train. If I do not have enough pre-load I will have to either get different lenght push rods or invest in an adjustable rocker system.
Click to expand...

If you want to switch to adjustable just swap over to aftermarket 1:6 small block chevy rockers- way cheaper than mopar specific rockers I know Crane makes a guide plate for this aptication I'm sure comp and other companys do also.
 
I just got my motor in , 318 +.030 ,KB 167's , Comp XE268H cam , Magnum heads and I have a little valve train noise as well . My preload is .025 . I used a Hughes adjustable push rod and lifter and measured and 7.60 , then purchased the MP pushrods . Hughes said .015-.020 preload was enough .I'm going to run mine and save for a set of Crane Energizers.
 
My engine is strickly a street motor and will likely never see the high side of 6000 rpm so I really do not want the expense of adjustable rockers if it's not absoutly necessary.

The issue with the Chevy rockers is the stud they mount on will not thread into the magnum head and they are not the correct length. You will still need to come up with studs to mount them on which seem to be tough to come by unless you purchase a mopar specific rocker set that come with them.

If my preload turns out to not be within acceptable limits the most cost effective fix will likely be custom lenght push rods. The other alternative if I only need a few thousandths is to face the rocker mounting pedastals.

Frankwest, thanks for the input that you are experiencing the same thing with the same cam. Even though all the reasons for there being more valve train noise make perfect sense it gives me a much warmer feeling that some one else is actually experiencing it.
 
Hughes recommended a set of adjustable pushrods for my applacation . @ $152 plus shipping . Also if you go with the adjustable rods you will need to cut off the push rod guides on the mounting plates for the stock rockers. If you decide to remeasure you are welcome to borrow the adjustable lifter/pushrod .

Frank
 
Dave, The KRC kit comes with
KRC Performance lightweight, high rpm stainless rocker kit with steel guide plates, ARP studs and poly locks. 1.6 ratio only
all for $349. You know you want them. Let me know how they are. LOL
 
Gee! where would I like to spend $349 first ? ;)

1. New rear leaf springs,
2. Professionaly installed headliner so I can get rid of my half *** job,
3. Bigger meats for the back,
.
.
.
.
N. Adjustable rocker arms.

Like most everyone I have a limited amount of resources and have to plan my expenditures!! :)

Like the new 360 to replace a perfectly good \6. The engine set me back a little over $2k but the total cost is closer to $6k because I had to promise the wife new kitchen cabinets to get her to allow me to do the engine!!!!!!!!
 
if you need tires the m/t street radials are awsome!!!
they is some adjustable self-aligning rockers on ebay for $200, so you don't need guideplates. if the headliner is the last thing to be done, id go for that..

steve
 
Hi all.
I also installed a Comp cam XE274H-10 in my 360 with stock 915 heads which is a step higher than the XE268H-10. I must admit that yes it is a little noisier than the previous experiences I have had. I have adjustable roller rockers and winding up the preload to one turn did not make a difference. I have my preload at 1/4 turn. No difference. I didn't notice it at idle but you can slightly hear the "machine type" noise the engine makes at moderate revs. Over 3000 rpm the engines starts to sing quite well. Mind you I have a very quite exhaust. You can pick out every noise. I have also noticed that the lifters rotated very slowly. Is this a problem? It takes alot of lifts to make a turn. I should of installed the XE268H-10. XE274H-10 is too radical for me.
Billy D....
 
The lesser the preload the better the motor revs (more power up hi rpm). 1/4 turn to my adjustable rocker equates to 0.010" to 0.012". Like I said it made no difference between one turn (0.040") and zero lash as far as lifter noise was concerned. 0.060" preload is unheard of. It is way too much. It will make the engine rev more "lazy" so to speak.I have Eaton lifters and they recommend 0.008" preload. Mind you I am using straight mineral 20w 50 oil. Still running in. My rod lenght is 7.300".
Billy D...
 
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