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Nova Tech Current Topic: Noisy rockers |
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#1
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I have a question about a new build chevy BB with a comp cam/hydraulic lifters and aluminum roller rockers. I've read where they are noisy. But, this noisy? sounds like a diesel. Anyone have thoughts on this...Thanks
https://davisions.com/nova/rockers.MOV |
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#2
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Welcome to Team Nova!
Sounds like adjustment, you shouldn't hear them at all, how did you adjust them?
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75 Nova Custom 75 Nova Base |
#3
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Many different ways the last was the E/O I/C method.
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#4
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That is the correct way, but how did you adjust them, 1/2 turn past zero lash?
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75 Nova Custom 75 Nova Base |
#5
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Yes, half turn
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#6
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What brand are they?
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-------------------------------- 64 Nova 77 Nova, 406, TKO 600, 3.73 8.5" 10 bolt SOLD 72 Chevelle Concours wagon |
#7
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How much oil pressure do you have, and do you have oil flowing at the rockers? BTW, are you using a Rhoads type lifter?
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75 Nova Custom 75 Nova Base |
#8
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#9
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Do they clatter at high rpm or just at idle?, how much oil pressure at idle?
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75 Nova Custom 75 Nova Base |
#10
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Flat tappet cams require specific break in procedures. Light springs, 2000 rpms for 20 minutes, proper timing and not stoppinguntil finished. Even following the procedure can occasionally fail to get the proper lifter rotation causing the cam lobes to wear quickly.
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-------------------------------- 64 Nova 77 Nova, 406, TKO 600, 3.73 8.5" 10 bolt SOLD 72 Chevelle Concours wagon |
#11
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Idle pressure is 20-30 and I'm pretty sure the clatter was at all rpms. We did the break in as specified 10 min at 3000 and 10 min at 2000. As mentioned in another forum...a similar build they had to go with longer push rods than what I have so I ordered new rockers >COMP Cams 1620-16 Ultra Pro Magnum Rocker Arm Set w/ 1.7 Ratio for Chevrolet 396-454 w/ 7/16" Stud
and will get the rocker geometry correct and measure the push rods to get the right ones. It's possible the ones I have are too short. I will inspect the lifters also. |
#12
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Did the lifters clatter right from the start or come in later?, did you cut the filter open after break in? and why new rockers?, how much shorter are the pushrods from stock? couldn't have been that short to cause that or you would have noticed something was not right I would think?.
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75 Nova Custom 75 Nova Base |
#13
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ugh, finally getting around to checking the engine. I had ordered new steel rockers and was going to get proper rocker geometry and check push rod length and order new push rods if needed. We pulled off the intake and I immediately saw what I didn't want to see.
some (4) lobes rounded and the two cylinders that the rockers loosed up the lifters collapsed and destroyed. The engine has less than 30 minutes running. I feel like an ******* for thinking this would be as easy as when I built my 283 back in 1975 I should of did more research and asked more questions and NOT rely on Jegs for all my needs. After several " you sent the wrong parts" calls with them I should of been on high alert. So we ripped the engine out today stripped it and I will include pics at the end for your opinion on bearings. I know we need a new cam and lifters. But upon researching and scratching our heads as to why this happened I see that jegs sent us the wrong pushrods. Standard deck heads listed everywhere call for 8.28" intake and 9.252 exhaust and their part number #249-7954-16 say that's what you get. Ok, well after tearing it apart I see the exhaust rods are actually 9.650 and intake are correct. researching this I found out these are for tall deck heads. I took their word when they said "these are the push rods you need" So nothing I can do except pull up my pants and redo it. Do you think I should replace the cam bearings? and take a look at the rod bearings. Like I said it ran less than 30 mins total. Gosh what a kick in the *** and money tossed out the window. https://davisions.com/nova/IMG_5063.jpg https://davisions.com/nova/IMG_5069.jpg https://davisions.com/nova/IMG_5066.jpg https://davisions.com/nova/IMG_5071.jpg |
#14
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Lesson learned the hard way, ALWAYS check and double check everything and measure, and always cut the filter open after break in, it tells all kinds of stories and you would have known right away something was wrong. now it all needs to be torn down and totally cleaned, an cam bearings need to be taken out since the holes in the bearings are smaller than the oil passage, if any gouges in the bearings they will need to be replaced.
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75 Nova Custom 75 Nova Base |
#15
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