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Discussion Starter #1
Can the camshaft in an assembled engine with hydraulic lifters be accurately degreed? I am planning on taking readings off of the pushrod tip with the rocker removed but am concerned that the hydraulic lifters may collapse slightly and give bogus readings.

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To get the most accurate reading I use a solid lifter .It is best to do with the heads removed but an assembled engine in the car is not impossible,just aggrivating..
 

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Boldly procrastrinating
66 El Camino 57 Chevy pickup 2004 Tahoe
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Kevin,

Depends a little if you're just checking or if you're going all the way in to change something, but this will help.

Pull all the sparkplugs out and drop all the belts. Pull the fan, upper pulley and lower pulleys to get some decent access. You might even want to think about dropping the water pump. You'll need some kind of positive stop that bolts in the sparkplug hole to find TDC for real. Adjust it so the marks you make on the balancer/degree wheel when it stops the piston are about 2" or so apart, then split the difference for the real TDC mark on the damper/degree wheel.

Yeah, it'll get a little aggravating when you're trying to stop it at exactly .050 lobe lift, but it can be done. When (not if) you go too far, back it up an eighth of a turn or so and try again. IOW, always approach the .050 point from the normal direction of rotation, not backing up.

All you need to check is the opening point of the intake valve, that'll tell the story. What cam do you have, have you looked up the numbers yet?

Tom (don't forget, the front valve is not an intake on a Chevy...)

[This message has been edited by Tom Mobley (edited 01-23-2000).]
 

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I don't think you will be to accurate with a hydraulic lifter. You realy need a solid lifter to check the crank degrees at .050 lift. With a hydraulic lifter the lifter has some internal movement. You will definetly have to remove your valve spring to avoid compressing the hydraulic lifter.
 

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Kevin, I don;t remember if it was you who asked about measuring lift of an unknown cam. I replies that, yes, it can be done using a dial/mag base and using the inside ( pushrod side) of the rocker. But checking lift and dialing in a cam are two different things. I hate to take the long road, but I would'nt be dialing in a cam without removing the intake and running my dial indicator in the lifter valley off the edge of a tappet. The few times I have done this it's a very critical operation. I wouldn;t use the blancer as reference either, mount a bonafide degree wheel. It's much larger diameter increases accuracy.
 

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Kevin,

Are you truely wanting to degree the cam or just assure that the timing marks on the cam
gear and crank gear were properly aligned??
 

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Discussion Starter #9
Well, Id have to say I got enough replies on this one.

I have a degree wheel, dial indicator, and piston stop. What Im planning on attempting is verifying my cam card specs (224x230, .51x.52, 110 sep, at 106 lc) on an engine already installed in the car. I am planning on pulling the water pump to gain clearance for the degree wheel (11 inch). I then will remove the #1 intake rocker and want to check lift, intake centerline, and duration at .050. I will be leaving the heads on and taking measurements off of the pushrod tip. I was not sure if I would be able to do this
with a hydraulic lifter and still get fairly accurate readings.

Yes Randy, this is related to my carb problem. I ran a carb sent to me by the machine shop and it did the same thing. I figure its time to rule out the camshaft being the problem once and for all. A possiblilty I didnt consider is that maybe the wrong cam got installed. The comp cams instruction sheet tells you to verify the cam number before installation, so Im sure they have had this problem before. I guess you could install the wrong cam and not know it if you only checked the intake centerline during installation. Remember, Im only pulling like 11 inches of vac at 750 RPM. Could be a cam with a greater overlap.

Can anyone tell me if and how much the hydraulic lifter will effect my readings? If I need a solid lifter to take readings off of does anyone have an old one they want to part with?

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Kevin, oooh, I forgot what a prob you were into. I know that with Crane the grind # is on the front snout of the cam. Check location of grind # with Comp and I;m thinking it may be easier to pull timing cover. Just a thought.
 
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Kevin, I had one Comp Cam that was ground wrong. I built a 350 for an El Camino, car over heated, ran bad, the whole deal. I never got any explanation from Comp, just a new cam and all the related work. Good luck!

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Wally
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67 Malibu "Small Block"
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71 Malibu "Small Block"
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Discussion Starter #12
Well,I would actually be releived to find out that I had the wrong cam or an improper grind. Ive been troubleshooting this problem for the better part of the last 3 months.

A few more questions....

If you pull the timing cover do you have to drop the oil pan? Does this require an entire new oil pan gasket as well as a new timing cover gasket?

Is it possible to purchase just 1 solid lifter to use while degreeing the cam or do I need to buy a set of 8?
 

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Kevin,
You'll have to remove the front four or five bolts on each side of the oil pan inorder to pry the front of the pan down (approx 1/2") to get the timing cover out/in. I usually drive a large screwdriver into both sides of the pan, between the block and pan, to wedge the pan down, leaving them inplace, as far as new gaskets/timing cover seal, that depends on how old they are, and how you feel about silicone. Most auto parts stores will sell you one lifter. Be sure you ask for a solid/mechanical.

RicksRag

PS: Sometimes I've found it further ahead to drop the oilpan and go ahead and replace the gaskets, to ensure no leaks.
 

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if the motor has been sitting a long time remove the lifter and pump it up in a small dish/bucket of oil.. even without doing that, there is no way its going to collapse under the pressure of a dial indicator

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Mike Reeh
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Yeah, I'm with Mike and I was thinking the same thing. Mike, what if you deliberately bottomed the lifter, assuming one of you guys knew exactly how??, the pressure of a dial indicator tip would not cuase any more comrpession.

A speed shop or well equipped GMPP dealer should be able to get you a solid (1).

I've done the timing cover deal a few times many moons ago to change cams. Just be extra careful not to bend any rails and you should be fine. No big shakes if you drop the front of the pan a freckle.

Good luck bud, we're tuned in for results.
 

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Discussion Starter #16
Im gonna try measuring off of the hydraulic lifter at the pushrod tip with the rocker arm off. I too dont believe the pressure of the dial indicator will depress the plunger in the lifter. If the readings dont match my cam card Ill pull the front cover and check the grind number on the cam. If the readings arent consistent I guess Ill have to pull the intake off and go the solid lifter route.

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Discussion Starter #17
Well, I degreed the cam off of the pushrod tip with the rocker removed using a hydraulic lifter. The readings for duration, lift, and intake centerline matched the cam card. I could not match the cam cards specs at .006 lift, possibly due to the lifter, dial indicator, or some geometry differences created by trying to measure off of the pushrod tip. I have not yet measured the lobe separation. Nevertheless, since the lift, duration at .050 (intake and exhaust), and intake centerline match the cam card I think I can conclude that I have the correct cam and it is installed correctly at a 106 centerline.

An interesting note is that when I set the engine up at TDC I discovered that my timing mark (on the balancer an the tab) was off 4 degrees. Top dead center read 4 degrees BTDC on the tab/balancer.

This is an easy check with the heads on using a screw in piston stop. I wonder how many other guys out there have incorrect timing marks? I'll either make a mental note of this or correct it by adding some timing tape to the balancer.

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