SR20DET S13 Blacktop cam channel score - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

skai · 06-07-2020, 05:07 PM

I'm rebuilding my sr20det and noticed these huge score marks on the exhaust side of the cams. Are these supposed to be like this from the factory? There are matching marks on the caps as well. Looking online at other engine photos of the similar motor, I'm seeing the same thing as well. Any response would be great as I'll possibly have to get a new head if it's not the case.

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S14rebuild · 06-07-2020, 07:05 PM

Yes those are suppose tobe there, but in the first pick looks like worse oil issue do to wear marks on the journal

skai · 06-07-2020, 07:10 PM

Thanks. Could that be lightly sanded down or machined off?

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Kingtal0n · 06-08-2020, 07:30 PM

That aluminum journal should be polished. All that embedded material needs to be removed. Also the burrs on the edges of the journal need careful removal and polishing.
It should look clean, like brand new, if you are rebuilding it proper

If you had a SEM to look up close at those journals the way they are, you would tell me there is no way no how the engine will run properly for very long the way it is.
The surface is critical to engine wear, oil flow, longevity

skai · 06-08-2020, 08:05 PM

Thanks for all the feedback guy. I'm going to see if I can get it machined properly.

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Kingtal0n · 06-08-2020, 08:59 PM

well. honestly never take anything to a machine shop. I would try and just clean it yourself.

Do that or get another head. I don't know if you can find a machine shop which will properly take care of that area. Maybe I am wrong though, good luck.

If you are unsure how to start, you can try rubbing it with some soap and water. Some kind of light degreaser. Don't spray it on to the head directly just wiping with a towel. Try to determine if the debris is really 'stuck' in the metal or not. Sometimes it will clean up without much effort. Other times... you might have to resort to rougher methods, polishing wheel on a dremel or something. Get creative but use low speeds, low force, lighter materials, like cotton cloth. Think polishing. Maybe try some aluminum polish. I've never had to do what you need to do before so i dont have an exact answer, but I do know that you had better ask what the machine shop intends to do before letting them do it and wasting your time.

skai · 06-08-2020, 11:13 PM

Thanks. I'll double check with the machine shop before anything. Going to try and clean it up best I can first as well.

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06-07-2020, 05:07 PM	#1
skai Join Date: Sep 2014 Location: Wisconsin Age: 38 Posts: 23 Trader Rating: (0) Feedback Score: 0 reviews	SR20DET S13 Blacktop cam channel score I'm rebuilding my sr20det and noticed these huge score marks on the exhaust side of the cams. Are these supposed to be like this from the factory? There are matching marks on the caps as well. Looking online at other engine photos of the similar motor, I'm seeing the same thing as well. Any response would be great as I'll possibly have to get a new head if it's not the case. Sent from my Pixel 4 XL using Tapatalk

06-07-2020, 07:05 PM	#2
S14rebuild BANNED Join Date: May 2019 Location: Florida-FAIL Posts: 2,495 Trader Rating: (8) Feedback Score: 8 reviews	Yes those are suppose tobe there, but in the first pick looks like worse oil issue do to wear marks on the journal

06-07-2020, 07:10 PM	#3
skai Join Date: Sep 2014 Location: Wisconsin Age: 38 Posts: 23 Trader Rating: (0) Feedback Score: 0 reviews	Thanks. Could that be lightly sanded down or machined off? Sent from my Pixel 4 XL using Tapatalk

06-08-2020, 07:30 PM	#4
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	That aluminum journal should be polished. All that embedded material needs to be removed. Also the burrs on the edges of the journal need careful removal and polishing. It should look clean, like brand new, if you are rebuilding it proper If you had a SEM to look up close at those journals the way they are, you would tell me there is no way no how the engine will run properly for very long the way it is. The surface is critical to engine wear, oil flow, longevity

06-08-2020, 08:05 PM	#5
skai Join Date: Sep 2014 Location: Wisconsin Age: 38 Posts: 23 Trader Rating: (0) Feedback Score: 0 reviews	Thanks for all the feedback guy. I'm going to see if I can get it machined properly. Sent from my Pixel 4 XL using Tapatalk

06-08-2020, 08:59 PM	#6
Kingtal0n Post Whore! Join Date: Jul 2005 Location: South Florida Age: 41 Posts: 4,828 Trader Rating: (17) Feedback Score: 17 reviews	well. honestly never take anything to a machine shop. I would try and just clean it yourself. Do that or get another head. I don't know if you can find a machine shop which will properly take care of that area. Maybe I am wrong though, good luck. If you are unsure how to start, you can try rubbing it with some soap and water. Some kind of light degreaser. Don't spray it on to the head directly just wiping with a towel. Try to determine if the debris is really 'stuck' in the metal or not. Sometimes it will clean up without much effort. Other times... you might have to resort to rougher methods, polishing wheel on a dremel or something. Get creative but use low speeds, low force, lighter materials, like cotton cloth. Think polishing. Maybe try some aluminum polish. I've never had to do what you need to do before so i dont have an exact answer, but I do know that you had better ask what the machine shop intends to do before letting them do it and wasting your time.

06-08-2020, 11:13 PM	#7
skai Join Date: Sep 2014 Location: Wisconsin Age: 38 Posts: 23 Trader Rating: (0) Feedback Score: 0 reviews	Thanks. I'll double check with the machine shop before anything. Going to try and clean it up best I can first as well. Sent from my Pixel 4 XL using Tapatalk