SBC 350 top end noise
I have a top end tick that I can't find the cause of. Brand new Lunati cam (10120701), lifters and matching springs installed two weeks ago. No retainer/guide clearance issues, no coil bind, no retainer/rocker arm interference no rocker arm/valve cover contact, no collapsed lifters. Pulling 30 psi oil pressure at idle and 45-50 at cruise.
Valves have been adjusted 1/2 turn past zero lash, both static and while running with no difference. Replaced old stamped rocker arms with brand new OEM replacements and that took only a slight bit of the noise away...at least for a little while. I'm running Vortec heads on an older block. The same noise was there with the old stock heads, thought changing things out would quiet it down. Eliminated all belt driven accessories (alternator, water pump and power steering). I'm at a loss and it's driving me nuts. Been turning wrenches on SBCs for 25+ years and have never had one stump me like this. Any ideas? Here is a short video of what it sounds like. http://youtu.be/B99cClzos1c |
Re: SBC 350 top end noise
Sounds like you've covered the majority of possible causes.
Is it both sides? Seemed louder on the passenger side in the vid. Wiped cam lobe? Bad cam break in? Something in the distributor? 30 psi seems low to me for oil pressure but its well within the safe range. Maybe connection between distributor and oil pump? Unfortunately sounds like you might have to really do some digging. That would drive me nuckin futs. |
Re: SBC 350 top end noise
Did you install the self aligning style rockers?
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It seems slightly louder on the passenger side to me as well. Break in went perfect, no issues at all. Truck runs like a scalded dog. All the rocker arms have been measured for travel and match the lift specs of the cam.
No metal particles in the oil, that was the first thing I checked. The reason for the new cam was 6 wiped lobes on the original because of the oil I was using. Found out the hard way that these old flat tappet cams don't like the lack of ZDDP in their bath. I was thinking possibly distributor too, (it is an Accel after all) but nothing indicating that as the cause when I put the stethoscope to it. As a matter of fact, neither the stethoscope or a length of hose to the ear has helped pinpoint the source. Even replaced the header gaskets to eliminate that as a possibility. I hate not being able to solve this problem, but may have to start collecting the pieces to put the 355 block on the engine stand together to have a little more peace of mind. This old 84 K10 is going to be my daily driver soon and don't want to have to concern myself with reliability issues. The engine is the only thing that I have not completely rebuilt on this truck. Everything but the rods and pistons have been replaced at some point in the last year as I got parts together. |
Re: SBC 350 top end noise
If hes running guides he shouldn't need the self aligning rockers arms. As long as there is adequate pushrod clearance.
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My bet is the noise is the nature of the beast with the aggressive lobe designs of the VooDoo/Extreme/etc.
Some aluminum valve covers amplify this. |
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Did you make sure the pushrods were the correct length? If you reused the old ones the tips of the rockers might be sliding off the valvestem?
Im trying to think outside the box here, I know its not likely but stranger things have happened. I just got done tightening one rocker arm on my buddies vortec crate engine we installed a couple years ago. It was number 8 exhaust. We didnt touch the rockers during installation and everything looked perfect under the cover. Just that one rocker was loose, the nut just decided to back off that day. ??? |
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Maybe I missed it but, I don't see where he said he is using guide plates.
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Using some old stamped valve covers I picked up at the bone yard. |
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Is it oiling up top? 6 flat lobes can leave ALOT of debris in an engine.
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What lifters? I rarely use flat tappets anymore but, when I do, I use the GM hard face lifters from Chevrolet Performance.
You are going to have valvetrain noise with the VooDoo line of cams, yours does seem extreme on the video. |
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Try changing your oil, use a good Wix 51061 oil filter (NAPA 1061) and some Valvoline VR1 30wt racing oil in silver bottle (plenty of ZINC)
http://www.valvoline.com/products/co...ng-motor-oil/6 |
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Good Morning, I'll chime in on this a bit. Have you determined if it is cam or crank rpm based. If cam rpm... have you listened to the fuel pump yet? They have been known to make sounds like this. If it's crank rpm based... When does the ticking start, cold, hot, when revving up or winding down? This should lead to whether it maybe a piston or rod sound. Well just trying to help. Seems to me if it was there before all the work was done and it's still there, the fix would be something entirely separate not yet addressed.
All have a great day, God bless, Terry |
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