Help me diagnose this sound.

[posulli88]

Had an exhaust leak and thought that was the sound I was hearing. Finally found and fixed the exhaust leak (I put the wrong style collector on my header ) That solved one issue but I am still hearing this sound.

Its a rhythmic clicking/ ticking sound you can hear at idle but you can hear it more on acceleration. I am hoping its just loud injectors in the Holly sniper system but I cannot tell. Hope this video is clear enough... Let me know your thoughts. Engine is freshly rebuild by Rick (SC/397) I have a little over 100 miles on it so I am not super familiar with the engine sounds. Oil pressure is great 60+ at cold idle 25+ at warm idle...

https://youtu.be/JP0ibnx2I5U

[PlasticBoob]

What kind of cam is it running? Sounds kind of like one with aggressive closing ramp angles. My Comp Cam makes a similar racket after it's all up to temperature.

No big deal, but it drove me crazy for a couple of years measuring everything and getting second opinions from old school V8 mechanics to try to figure out what it was.

Not saying that's what yours is, but it sure sounds similar. Either that or maybe some loose preload, but I doubt SC/397 would let it get out the door with any issues.

[PlasticBoob]

BTW, your engine would be much happier if you ditch the hot air intake.

If you click the video in my signature and then skip to 2 min 18 sec you can hear what a hot Comp Cams XE sounds like. That day my idle was set high and tuned for max vacuum (power AFR <14.7:1), which makes the valvetrain noises even more apparent.

[babywag]

open elements amplify injectors, they will be pretty noisy with it.

honestly diagnosis of noises via videos is tough. sounds are never the same as what you are hearing in person.

Get a wooden dowel or loooong screwdriver/pry bar/etc.
One end to ear other end to suspected noise source.
It will reveal the culprit.

[PlasticBoob]

Definitely hard to diagnose with video. x2 on the dowel/screwdriver/stethoscope.

Not trying to be disagreeable, but here's what injectors sound like. Go to 50 seconds and ignore the high pitched whine from the idle stop screw:

https://youtu.be/Ua0D4yFXK8k

Yeah my video has lousy audio, but his doesn't sound like injectors to me - sounds more metallic like the valvetrain. Injectors have more of a soft ticking without that ever-so-slight metallic "ringing/echo" if that makes any sense.

[posulli88]

It does have a comp cams 268H cam in it with forged pistons with the compression right under 10:1 and I think most would consider it a relatively aggressive cam. I have never owned an engine like this so I am just not sure what sounds are normal and what sounds are bad haha. Also don’t think Rick would let it out of his sight if preload was wrong. I have been going around with a long tube and there is definitely noise from the fuel injection and from under valve covers just not sure if it’s normal or not haha.

I will try the dowel trick. I guess I could remove valve covers and have a look at the preload again and just make sure everything looks normal.

What air intake do you guys suggest? My engine did not have an air cleaner on at all when I got it so I bought the K&N

[PlasticBoob]

Surprise surprise, haha.

268H is Xtreme Energy, right? Personally I'd say you're fine and it's totally normal for that type of cam. Keep an eye on it and see if it gets any worse, but otherwise enjoy! Hot rod engines make hot rod sounds.

It's disconcerting at first but you get used to it after a while, though I have to say that yours sounds a little more "loose" (for lack of a better word) than mine - but that might be because you have a bigger cam than my 256. They sure slam those valves down hard, but man do they make a nice powerband.

I was at a car show once and heard a Chevy making the exact same type of noise and thought "that sure sounds like my Jeep!" - surprisingly when I talked to the guy he said he had a Comp Cam in it.

[PlasticBoob]

Air intakes are tricky. I had to put one together using a bunch of parts, here's the thread:

http://www.ifsja.org/forums/vb/showthread.php?t=145690

I should have gone with 3" instead of the overkill 4" and would recommend the same for anyone else. Not sure how much torque I'm losing with that huge of an intake tube but the Jeep is still plenty strong.

[posulli88]

The Comp Cams 268H is the High Energy level not Extreme. Its 110 degree lobe seperation 268 duration (218 at .05" lift) Valve lift is .456 and lobe lift is .268.

Here are its specs: http://www.compcams.com/Company/CC/c...x?csid=15&sb=0

Thanks for the Cold Air post. Super helpful! Maybe a project for me down the line.

[johnsonic]

I have a fresh rebuild as well and am running the 260H, 9.1:1 compression. Around 100 miles right now, and I have a similar noise but seems to be getting quieter with mileage. Going to change the oil soon and pull off the valve covers to doublecheck preload, measure lift just in case I wiped the cam.

So... following this thread hard.

From the threads I've seen SC/397 runs a few gallons of gas through the motor and it's broken in when you get it - so am hoping it's a normal noise!

I know it's hard when you have a unique motor and don't know what it should sound like. Every noise becomes the loudest noise!

[fsj454]

oil

Hi and nice job . I would like to now what kind of oil you are running . Was motor up to temp for video or cold . I just put a AMC rebuilt engine together and it does not sound like that . What I would do first is change oil to Amsoil Z rod oil 10 30 . It sounds like you have wrong oil in motor

[posulli88]

I am running Comp Cams 10W 30 break in Oil and then a bottle of a Zinc Additive per Ricks instructions. I have only probably put 100 miles on the engine and Rick Suggested doing the first oil change before 1000 miles and go to the oil I will run regularly from then on. His oil suggestion is 15w40 Rotella with a zinc additive. I will reach out to Rick to get his thoughts as well. Like I said before Rick is a pro so I am sure the preload is correct.


The engine was up to temp in the video (155 degrees) and has around 25 psi at hot idle 60 when cold... The Noise is definitely more noticeable when the engine is warm. I don't really hear it until the engine warms up.

[fsj454]

Check Oil

I think oil is contaminated .To much junk in oil assembly lube .cam lube .bearing lube and so on .I always beak in engines for 2 or 3 hours and drain oil . And put fresh break in oil in . I never use that zinc additive .Rang a stang had big problems when he broke his motor in with all that crap stuck in the oil filter . I use Amsoil break in oil 1 case . and 2 good oil filters to properly break in new rebuilt. I think that junk is in oil filter and staving top end of oil .Just my 2 cents oil is cheep insurance

[posulli88]

When Rick Builds the engines he breaks them in and changes the oil and filter and then runs them more before sending out the engine so he is checking two filters and oil changes. So the oil and filter I have in it now is the 3rd round in about 100 miles worth of running if that makes sense (two changes for Rick, 1 for me when I received the engine) So I don't think it would be contamination. Im thinking I change to the Rotella Rick suggest and check the filter when I pull it for contamination. Hopefully that solves it.


With 60 psi warm idle and 25 cold of oil pressure I would think oil would be getting to the top end.

[fsj454]

cam kit

I purchase a comp cam kit extreme but it was to large for me . So I got a rv MT 1 cam . But when I looked and inspected lifters that cam with comp cams kit they were not up to my standards plungers were sticky and did not move up and down smooth so. I purchased old stock Federal Mogul lifters made in USA and compared to comp cam lifters and they where not sticky and worked as they should . Just cause it is new does not mean it is good. So I have a new set of comp cam extreme energy lifters if you need .