eBay Reground Cam

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indirect_connection

indirect_connection

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I made my first attempt at degreeing a cam this past weekend. Magnum 360 block I'm attempting to rehab on the cheap. My cam core was pitted/flaked on a few lobes, plus I wanted to run a mechanical fuel pump, so I purchased a LA roller regrind off of ebay. Same seller and similar to this one: Hydraulic Roller Camshaft Mopar LA HR-268-SBMd 318 340 360 Demon b | eBay

The specs are as follows:

Advertised Duration
In. 268
Ex. 276

Duration @ .050
In. .215
Ex. .218

Valve Lift 1.5
In. .489
Ex. .503

Lobe Lift
In. .326
Ex. .335

LSA
112

After much fiddling, I finally got the degree wheel set to TDC and the flexible dial indicator mount steady. The tip of the dial indicator was centered in the pushrod cup of the lifter. The duration at .050 looked right on for the intake, but exhaust was low. I was also reading over .300 lift on the intake, but only .280 on the exhaust.

IMG_1598.JPG
IMG_1596 (1).JPG


I was starting to doubt my measures. I pulled the lifters on Cylinder 1, and disassembled one. I stacked washers inside and put the lifter cup back on. I also used a magnetic base instead of the flexible one. The exhaust lifter must have been loose, because my readings came up to .290 lift, but intake stayed the same.

Now this is well below the specifications. I'm running no name Edelbrock heads I purchased from Mancini, which should be good to .550 lift. I feel I'm leaving a lot on the table.

So my question is, have I eliminated all variables to my measuring? I'm about ready to pull the cam, and try and get my money back through paypal.
 
Are you using a flat tappet to degree a roller cam?
 
The lifter retainer collars make that a little difficult, especially being a small base circle cam. The lifter bodies end up being below flush. I assumed that the stack of washers would eliminate any play in the hydraulic cylinder.
 
I would start by removing the lifter spider, dog bones, and lifters, then using the dial indicator directly on the camshaft lobes to verify the lobe lift only, nothing else. This would help you eliminate more variables to know you are getting true readings of lift.
 
First of all you are measuring on an angle, indicator shaft needs to be in the plane that the lifter is. Also how much is the lobe higher than the base circle of the cam? Remember rocker arms are a theoretical 1.5 to 1 ratio.
 
Pulled cam and measured with vernier calipers (no micrometers at home). Similar. Coming out at about .305. So at 1.6 rocker ratio I’m going from .536 lift down to .488. Seems significant.
 
The camshaft timing events are more important than the lift. And I see they have a note on their listing that says you will have to pay shipping on a return that is not as described. I guess maybe that is going to be a red flag.
You can either run it with 1.6 rocker arms if that is option for you or 1.5 rocker arms, and IF the rest of the opening/closing, duration, and etc are suitable for your combination. Otherwise, you could try contacting them to see what they say about it. Maybe their listing was wrong on the lobe lift numbers. A Magnum engine would already have 1.6 ratio rockers from the factory, so if they ground the camshaft for that style of engine, the intended final valve lift is pretty close.
 
Watch the tip of your DI as the lifter rises and falls.
If it moves sideways in any direction, the axis of the DI is not the came as the axis of the lifter, and it will not read correctly;
because the DI-tip is climbing up the side of the cup.
If you make a flat plate to sit in the recess, and your DI-tip scrubs sideways..... see above.
 
I know that my findings don't mean the cam is unusable. I cheaped out when when I an extra 100 bucks could have gotten me a brand new Lunati. I read many recommendations on here for reground cams on Magnums, and the seller had 100% rating. I'm regretting the decision, as I have little faith in the quality if they were this far off on the quoted size. I may be stuck with it though, as I bought it in mid January. eBay's resolution period has passed, and it PayPal just redirects me back to eBay.

By the way, anyone have a spare lifter retaining clip? Mine took flight and disappeared when I removed it.
 
Oh yes. Basically told me that the the difference was due to requiring longer pushrods, which is BS since I was measuring at the lifter. Longer pushrods do not give you more lift, they just compensate for the material that was ground off the base circle. This was the response.

you can not measure like that. you have to add in the push rod additional length. those lobes are not "stock" configurations. it's not normal, thanks


 
indirect_connection said:
Oh yes. Basically told me that the the difference was due to requiring longer pushrods, which is BS since I was measuring at the lifter. Longer pushrods do not give you more lift, they just compensate for the material that was ground off the base circle. This was the response.

you can not measure like that. you have to add in the push rod additional length. those lobes are not "stock" configurations. it's not normal, thanks
Click to expand...

That's a load of crap. Was it the owner that said that or an employee?
 
Contact was through eBay, so who knows. I replied back today and told them I measured the cam lobes directly. We'll see if I get a response.
 
indirect_connection said:
If I do end up using the cam, I may have to create another post on where to degree it.
Click to expand...

Using the dial indicator method you have been checking with already, try getting the numbers to fill in a camshaft card, such as opening and closing events. You should be able to get close enough to know if that camshaft is worth running. Then, if you get stuck with it, you will be ready to go. With that info, you will probably be able to get closer to knowing where to install it.
You have stock pistons in the photos, so figure around 9 to 1 compression at best. So where this one appears to be ending up will still be much better than stock and not too far off from you expected to be. Then, just keep the degreeing questions in this thread, since this was all about the camshaft anyways. One stop for all the relevant info if you have more questions. This would be the cheapest route since you already have it.
 
indirect_connection said:
I know that my findings don't mean the cam is unusable. I cheaped out when when I an extra 100 bucks could have gotten me a brand new Lunati. I read many recommendations on here for reground cams on Magnums, and the seller had 100% rating. I'm regretting the decision, as I have little faith in the quality if they were this far off on the quoted size. I may be stuck with it though, as I bought it in mid January. eBay's resolution period has passed, and it PayPal just redirects me back to eBay.

By the way, anyone have a spare lifter retaining clip? Mine took flight and disappeared when I removed it.
Click to expand...

You need better lifters. You should get the ones with the snap ring instead of the wire clip.
 
RustyRatRod said:
You need better lifters. You should get the ones with the snap ring instead of the wire clip.
Click to expand...
I replaced all my clips with snap rings. I think I got them from Master Carr. Might not be recommended but did this with my 500 440 Stroker 6 years ago.
 
Reinstalled it today. Here's how it measures out. I installed it 4 degrees advanced according to the key way on the Summit roller chain.

Intake opening .005 at 20 degrees BTDC, .050 at 8 degrees ATDC
Intake is at full lift at 70-54 degrees BBDC.
Intake closes .050 at 40 degrees ABDC, .005 at 80 Degrees ABDC

Exhaust opening .005 at 72 Degrees BBDC, .050 at 42 Degrees BBDC
Exhaust is at full lift 58-80 ABDC
Exhaust closes .050 at 11 Degrees BTDC, .005 at 23 ATDC

Stock bottom end. Pistons are .050 in the hole. Head gasket .050. Heads are advertised at 58cc. Up top will be a Chinese Air Gap and a Quick Fuel 750 Vacuum secondary. Exhaust will be ground-dragger long tubes, and 2.5 duals with turbo mufflers.

For right now it'll have a stock converter and highway gears (either 2.76 or 2.94).

Car is a cruiser, I'm just looking for more usable power.
 
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