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Old 06-30-2019, 04:26 AM
Mrmonk7663 Mrmonk7663 is offline
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Default Rod hitting Camshaft-need help

Ok I have no idea what is going on. Installed an arc billet rod and mod 2 cam. The engine spins freely 1 3/4 rotations then stops. If I reverse the direction same result. Piston is at same height when it hits. I opened the side cover and the rod is hitting the camshaft. It is hitting on the rough area not the lobes. And yes I am 100 percent positive itís the rod hitting. I could see it making contact. See picture below. How is this even possible? Side cover was torqued to spec. Factory .019 gasket. Arc flywheel in the other side toques per arcís 65 ft lb spec. Engine has NOT been run so no damage has occurred.

I rotated the engine with side cover off and same problem. I pulled crank same problem. I pushed crank same problem.

I installed the stock camshaft without the sidecover and it did NOT contact and spun as much as I wanted.

Anyone ever seen this issue? What the heck is going on? There is NO head installed either.

Cam is supposed to be a DynoCam Mod2 purchased from NR Racing. On a different note 1 of the 4 head studs I received from NR Racing was only threaded on one end.

I measured the width of the area where itís making contact. Itís very rough and measured .64Ē The stock cam is much less rough and measured .572Ē. Is grinding this area an option? Or is the cam defective from manufacturing incorrectly?

The size difference is apparent with the naked eye as seen in the last picture. Stock is on top.
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Old 06-30-2019, 07:07 AM
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itsid itsid is offline
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contact NR racing,

if they cannot help you with that,
go up and contact DynoCams and ARC
show them these images and ask them what to do.
Maybe you're "lucky" and got a 'incorrectly' milled Con-Rod for your engine,
maybe the Camshaft itself is out of specs for one reason or another.
(some Hemi vs non Hemi issue eperhaps *shrugs*)

But don't start grinding yourself I'd say..
an imbalance on the camshaft can cause a really nasty running engine
(from premature bearing wear up to death rattle)

Haven't heard anything alike before
And IIWY that's something I would want to ask the manufacturer about first

'sid

PS waaait.. second pic.. is that the Dyno cam or the stock cam?
if the stock cam I'd be baffled,
since that very much looks like a true clone cam to me.
And if that's the dyno cam it's just the wrong one for a predator (non Hemi 212 right?)
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Old 06-30-2019, 12:00 PM
Mrmonk7663 Mrmonk7663 is offline
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All pictures are with the Dynocam Mod 2 installed. The last picture shows stock vs mod 2 where you can see how much bigger the unfinished area is. I am 99.9% sure it’s not the rod. The camshaft should not be almost .1” bigger in diameter. I’ll call everyone tomorrow. Hopefully they are reasonable and not dismissive.

In the last pic you can also see a big difference in the end of the camshaft on the machined portion. While this area is not the problem it illustrates the wide tolerance variation.

And yes Non-Hemi Predator 212. Straight from the box. Never ran.
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Old 06-30-2019, 01:05 PM
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Yea, that cam looks like someone forgot to finish out the machining process between the lobes. Looks like a raw casting in there.

Wes
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Old 06-30-2019, 01:09 PM
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Thank you for confirming I’m not crazy haha. I’m glad I found the issue before ruining the new billet parts were destroyed. The first build you always learn so much. I sent emails to NR Racing and Dynocams. I’ll see what they say and how/if they are going to make it right tomorrow.
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Old 06-30-2019, 01:46 PM
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I seem to recall having to clearance mine when I installed my stuff from NR racing on my big block. Don’t worry NR has always done me right and he has always gave me great customer service as well and some answers that I needed before ordering my goodies.
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Old 06-30-2019, 01:55 PM
Mrmonk7663 Mrmonk7663 is offline
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That’s good to hear. I’m not against ckearancing but if you saw it in person it’s a lot to take off..and it shouldnt have to be done on a build this straightforward. . The edges of the hexagon are not sharp/defined at all. It’s like this part was totally overlooked. Talking to NR last week on the phone when ordering they were nice and helpful so hopefully tomorrow I have good news.
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Old 06-30-2019, 02:01 PM
Randy H Randy H is offline
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You may want to check the cam journals as well.
The non hemi has larger journals than the hemi or clones.
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Old 06-30-2019, 02:05 PM
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Might be a good idea but at this point it won’t matter since regardless of that it won’t work. The rear journal you can see is much wider in the pictures above.
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Old 06-30-2019, 02:11 PM
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Good pics showing this minor travesty.

Wes says the area between the lobes looks like a raw casting but the stock cam appears the same, it just has a thinner cross section but the DynoCam should too IMHO.

The stock cam sports a better overall fit and finish. It wins the beauty contest.
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Old 06-30-2019, 02:31 PM
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Quote:
Originally Posted by Mrmonk7663 View Post
Might be a good idea but at this point it won’t matter since regardless of that it won’t work. The rear journal you can see is much wider in the pictures above.
It will verify that you indeed have the wrong cam. Or not.

I don't see any machining issues.

168f suggest a clone cam.
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Old 06-30-2019, 03:24 PM
Mrmonk7663 Mrmonk7663 is offline
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I don’t know the specs that I would be measuring against or where to measure what you are talking about. I have the calipers and can measure but need a bit more direction for this. Do you mean just measure the front and rear diameter of the journal where it goes into the block and sidecover? Do you happen to have the predator specs? I will say it fits nice and snug. Not loose.
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Old 06-30-2019, 05:04 PM
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Quote:
Originally Posted by Hellion View Post
Good pics showing this minor travesty.

Wes says the area between the lobes looks like a raw casting but the stock cam appears the same, it just has a thinner cross section but the DynoCam should too IMHO.

The stock cam sports a better overall fit and finish. It wins the beauty contest.
Yea, I just think that section between the lobes should have been finished up on the lathe before sending out. if it needs clearance by a customer what are they thinking? if a guy at home takes a grinder or dremel to that camshaft he is introducing flaws to the balance of it. Lets say your engine is gonna turn 9k rpm, that means your cam is still gonna turn 4500rpm, thats still a lot. it needs to be properly ground in the middle. Thats Bullsh!t to send out something for the average joe to be grinding on with a file or grinder or whatever. It just looks sloppy to me. Maybe i'm wrong, but it still ain't gonna work like it is.
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Old 06-30-2019, 05:10 PM
Mrmonk7663 Mrmonk7663 is offline
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Exactly my thoughts. And no matter what, this camshaft isn’t working out of the box. As soon as I hear from NR I will let everyone know the resolution. Thanksbyall like always.
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Old 06-30-2019, 06:40 PM
Randy H Randy H is offline
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Quote:
Originally Posted by BigWes View Post
Yea, I just think that section between the lobes should have been finished up on the lathe before sending out. if it needs clearance by a customer what are they thinking? if a guy at home takes a grinder or dremel to that camshaft he is introducing flaws to the balance of it. Lets say your engine is gonna turn 9k rpm, that means your cam is still gonna turn 4500rpm, thats still a lot. it needs to be properly ground in the middle. Thats Bullsh!t to send out something for the average joe to be grinding on with a file or grinder or whatever. It just looks sloppy to me. Maybe i'm wrong, but it still ain't gonna work like it is.
Modifying and grinding clearances are par for the course. Lol. I think you would not like modding a flathead. I'm sure there are thousands upon thousands of engines that cam will work fine on. It's basically just a stock cam, with a reduced base circle and the lobes knocked off to increase duration. Then flame hardened.
Options are buy a billet cam (still might have to grind here and there). Pay someone that knows what they are doing.

Quote:
Originally Posted by Mrmonk7663 View Post
I donít know the specs that I would be measuring against or where to measure what you are talking about. I have the calipers and can measure but need a bit more direction for this. Do you mean just measure the front and rear diameter of the journal where it goes into the block and sidecover? Do you happen to have the predator specs? I will say it fits nice and snug. Not loose.
Yes the bearing area. I don't remember the numbers exactly. I think .008" difference. I dug up an Isky Black Mamba, a cl4 and a few others. Hemi and non.
Of course my caliper battery is dead.
But that don't matter cuz your can compare the cams you have.

If worse comes to worse, look at Arc videos and contact Jody Powell. There's like a half dozen guys here that really know anything.
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Old 06-30-2019, 07:31 PM
Mrmonk7663 Mrmonk7663 is offline
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I understand all you are saying. But I don’t believe modification should be necessary here as it is sold and has been sold as a drop in camshaft that works in the predator engine. The hemi model clearly states grinding of crankshaft.ie that information is disclosed. Also the fact that tons and tons of folks have installed the Mod2 cam without grinding leads me to believe still that this cam is wrong either by incorrect cam being shipped or cam not finished properly. I will measure the journals tonight when I get home.
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Old 06-30-2019, 09:24 PM
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I understand what he is saying as well. I am also a certified A&P Mechanic and I also have years of experience working with machinists. Oh and I'm also going on 20 years member of a machinist union as well...so I'll say this...just because you can take a Dremel and bubba a camshaft and make if fit and make it work doesn't make it right. I can make that cam clear and work...but will fit be balanced afterwards? Is it balanced now?

It's a cheap engine...if you're throwing money around left and right it doesn't matter I don't suppose. It matters to me... because I know better...but I ain't bubba.

If the manufacturer says hey grind off .020 in this location and blend in to this radius it'll be ok then hey go for it...but for now... I'd wait and see what they say. I still don't trust it until the manufacturer tells me something different.

And yes I've seen some of those flathead cams before...looks like pencils between the lobes...those things also have bad habits of slinging themselves apart in the middle of the racing season too. And I love a flathead as much as anyone. But he also ain't building a full on racing engine either. He's just building something with a little more umph than stock. He says this in his build thread...which is nice if you want to follow it...

I'm actually considering doing a similar situation with a few of my engines...but I'll probably go with billet cams because I'm a grouchy grumpy biased ahole when it comes to things like this.

Call the seller, see what they tell you first OP, you have plenty of time to make your choices.

Wes
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Old 06-30-2019, 10:00 PM
Mrmonk7663 Mrmonk7663 is offline
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Much appreciated Wes. Go karts are my first adventure in small engine building...but not engines in general. Iíve built a handful of Ford v8s and 4cyl Miata engines from bare blocks. Iím a good mechanic but I am not a machinist nor do I have the intricate knowledge that a machinist has regarding clearances...most of us donít, which is why I (we) have an expectation for the product to work as intended, marketed and designed I do all I can myself but camshaft manufacturing and engineering is beyond my skill set.

My wife is clueless about anything mechanical. Doesnít even know what a nut or bolt is...truly. Last night I pointed at the area on the cam that hits and pointed at the same area on the stock cam and asked what was different. She immediately responded that the problem cam was ďa lot biggerĒ if she can see it then I know itís a problem haha. .

If I buy a product for an application it is not designed for then I expect to modify it accordingly to make it work. If a manufacturer or seller disclosed necessary post production modifications (as in crankshaft clearancing for HEMI engines, then again I would expect to have to do that This simply isnít the case in this situation.

I appreciate all the responses and opinions wether they line up with my opinion or not. Thatís why I post here anyway. We all learn from these situations and can help future folks new to the game.

Anyway, tomorrow we will see . I didnít know billet cams existed for these small engines. Thatís pretty cool.
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Old 06-30-2019, 11:30 PM
Randy H Randy H is offline
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Mrmonk, I'm sure you'll get everything sorted.

Here's a couple (crappy, sorry) pics for Wes. These are new DynoCams cl4's hemi/clone cams. One of em had been ground down a bit, other one hasn't. Same part #. I haven't done anything to them.

Buhaha, good luck getting any sleep this week.
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Old 07-01-2019, 12:16 AM
Mrmonk7663 Mrmonk7663 is offline
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Randy, I measured the journal that rides in the block. Both measure the same...around .557. There is one glaring difference though and no clue if it matters. The stock cam has a much larger hole. See picture. Stock left. Mod2 right. Also if you scroll up and look at the horizontal cam picture the shiny machined area directly behind the journal is wider than the stock cam. Again no clue what that means, if anything. Neither of these are the problem I’m having obviously but maybe it’s a clue for you?
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