scarring on camshaft

[Javi802]

So i bought some used jwt s4 cams from some dude on a Facebook page and just got around to unwrapping the second cam and found some scarring on the end of it.( unsure of technical term for that part of the cam)


Is this cam unusable?
[IMG][/IMG]

[jr_ss]

Id take it to a machine shop and have them mill/sand just where the scoring is. There looks to be enough bearing area on that portion of the cam to save it and make it useable.

[JSimpson]

Originally Posted by Javi802

So i bought some used jwt s4 cams from some dude on a Facebook page and just got around to unwrapping the second cam and found some scarring on the end of it.( unsure of technical term for that part of the cam)


Is this cam unusable?
[IMG][/IMG]

Thats pretty deep. Technically these are junk. Any engine builder would toss these. As a matter of fact they would toss ones looking much better than this. If you are putting them in a road car that doesn't see any abuse you could get away with it, but there is nothing good coming from stressing a rocker arm at an angle at 7,500rpm. If you leave them it will ruin the rocker. If you try to smooth them out it will stress the rocker at an angle, and if you evenly grind the cam lobe somehow, A its going to cost enough to just get a new cam and B these engines are pretty sensitive to cam lobe profiles across the board so its a bad idea. Why people buy used cams, rods, and other engine internals blows my mind. All of these parts have life cycles, even if the cams are half the price; they last half as long so you aren't saving any money. Good luck!

[Javi802]

Well, people rebuild engines all the time and retain some of the components the engine had in it before doing a rebuild. Whats the difference in me reusing them?

Obviously in this case the seller wasn't honest with me. So now im having to buy a new intake cam, but its my money wasted, not yours. Thanks for the input though.

Oh, and the exhaust cam looks fine. No gauges anywhere. I am going to have it polished though

[brndck]

I would not use a cam in that condition. Time to go after the seller for not disclosing the damage.

[jr_ss]

This scarring isn't on a cam lobe that hits a rocker. This rides inside the cam journal on the head. If it was a lobe, I would have suggested to bin these things as well.

[Nizzan4u2nv]

Rule of thumb is if your run your nail across and it catches then theyre junk. I bought a set of S1 KA cams and had JWT inspect them since theyre local and they recommended not to install mine which were much less worn than that.

[JSimpson]

Originally Posted by Javi802

Well, people rebuild engines all the time and retain some of the components the engine had in it before doing a rebuild. Whats the difference in me reusing them?

Obviously in this case the seller wasn't honest with me. So now im having to buy a new intake cam, but its my money wasted, not yours. Thanks for the input though.

Oh, and the exhaust cam looks fine. No gauges anywhere. I am going to have it polished though

The difference is a quality tool steel cosworth cam lasts forever, however a cheap soft JWT cam clearly doesn't. You re-use parts that are as good as new... Like studs/roller rockers/intake valves and possibly titanium rods in expensive engines, but thats only when they are perfect. Yours are not perfect. Lesson learned!
New cams+new rockers=no more worries.

[Javi802]

I'm confronting the dude. I don't see why people don't disclose shit like that.

I've never and will never sell something that i'm unsure about without letting a potential buyer know.

I'm naive for thinking that a total stranger could be trustworthy

[Kingtal0n]

Whatever you wind up doing, when the new cams go in, follow the FSM torque procedure.

[economix]

Originally Posted by Kingtal0n

Whatever you wind up doing, when the new cams go in, follow the FSM torque procedure.

This is a MUST. And use an actual in/# torque wrench or you can snap a cam in no time.

[TheRealSy90]

Since it's not on a lobe and just on a head journal I would have it polished and it should work perfectly fine, there's more than enough clean area on that journal, as long as all the rocker lobes are good. Especially since it's at the back of the engine opposite of the cam gears. Maybe if it was on the cam end i'd worry about it.

[Javi802]

Originally Posted by TheRealSy90

Since it's not on a lobe and just on a head journal I would have it polished and it should work perfectly fine, there's more than enough clean area on that journal, as long as all the rocker lobes are good. Especially since it's at the back of the engine opposite of the cam gears. Maybe if it was on the cam end i'd worry about it.

Thats exactly what somebody over at jwt said when i had emailed him this picture.

I guess ill take it to a machine shop and have them take a stab at it

[TheRealSy90]

JWT are the best in the business when it comes to sr20 cams as far as i'm concerned. Nissan has gone to them before to help them R&D cams for their own race team engines, they know thier stuff. I've had my s4's for over 5 years and still look like they did brand new.

[Javi802]

Hell yeah. I've read nothing but great things from people who have their cams. Not one bad thing.

That's why i'm really bummed out lol. Been looking forward to running these for the longest time.

If it does end up being no good i guess ill just save up and buy the one cam for $280

[JSimpson]

Originally Posted by TheRealSy90

Since it's not on a lobe and just on a head journal I would have it polished and it should work perfectly fine, there's more than enough clean area on that journal, as long as all the rocker lobes are good. Especially since it's at the back of the engine opposite of the cam gears. Maybe if it was on the cam end i'd worry about it.

Thats an excellent point. One could take a few thou off the problem areas in a lathe possibly there would be enough meat to get by. However this will cost some $$ and time. If the head journals are that rough, theres a distinct chance the cam lobes got their fair share of wear too.
Eyeball engineering on cams of a high revving engine, thats a way to lose sleep! If the new cam is only $280 thats a no brainer. I would feel like a real dumbass if I junked my head and scored up my cam journals over less than $280. The amount of limiter a peaky SR20 sees and how violent that is on cams.... Yikes!

[TheRealSy90]

I would think that if he just polished out the scarred area a little bit, which would give it a slightly smaller diameter, it shouldn't affect the head material at all? Plus it will have the oil pressure as well.

[jr_ss]

He has to have it turned first to remove any rough edges. Even if he took just a few thou off, he'd be better off for it. I don't think it needs to be polished as it won't be in contact with anything.

[cotbu]

The cams journal surface isn't completely used on that part of the cam, so maybe the previous owner installed the wrong cam cap or something. I'd test fit the cams, mark where the cam cap sits and have the remainder cleaned up, by a machinist. I surely wouldn't trash them just yet, it would definitely be after start and a hard run!.

Sent from a Highly Tuned Note 4.5!!!

[Def]

You could honestly take that down yourself with a small strip of ~220 grit sand paper cut to that shape. Take care to keep it right over the damaged area and lubricated with WD-40 or the like. A few minutes will take down any high points enough to not interfere with your journal.

I'd step up from the initial 220 to 400>600>1500 grit just to make sure you don't have any roughness that could catch on the journal. A small assorted wet sandpaper pack from Wal-Mart will have almost all the grits you'd need, and you can do that in less than 10-15 mins.