Thread: 396 BB troubleshoot tapping noise

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going nuts with this engine. it's a '69 396/325 sitting in a 66 Imp. purchased the car as it is and didn't receive alot of info. replaced the carb with a 750 Quadrajet and it runs 100% better. it does have full length hooker headers, dual ehxaust with ?flowmasters?
Noticed a tapping or clanking sound on the passenger side towards the front of the engine which sounded like it was coming from the valve train. Did a valve adjustment last week. have read so many differnt opinions on the amount of turn after full lash. anywhere from a quarter to a full turn. set mine a half turn after full lash. Noise went away. within 4-5 days it was back but the tapping was now on the drivers side. There isn't any noise from the engine when first starts and idles fine. It only happens after the engine has wqarmed up some. Did a compression check yesterday and was 145-150

any suggestions appreciated, constructive critism, help appreciated.
Have been told it could be the valve springs since Chevy did not but double springs in the 396 as they did in other big blocks. Been told it could be a leak in a header gasket.

Oh no----no spell check!!!!!!!!!!!!!!!!!!!!!!!!!!

Welcome to CHR !!!!! Header gaskets do have a nasty habit of sounding like a lifter out of adjustment....and a question, it only starts when the engine is warmed up??? What is your oil pressure doing from cold start to operating temp????? Could be something as simple as old, dirty, lightweight oil causing a bit of a pressure drop once the engine gets warmed....hydraulic lifters can get "loose" with low oil pressure..... Hard to say with no history on the engine, but a couple of things for you to look at, anyway....

Dave,

Just wanted to thank you for your warm welcome and advice. The cars in the garage and I would have to move two others to get ol' blue out. I did start her up and cold oil pressure was 65/67, ran up to 2,000-2,500 RPM's and pressure rose to 80, that's as high as the gauge goes. Car warmed up to about 160 and there was no change in the oil pressure.

Tomorrow I'll drive her around for about 30 min. and see if that makes a difference. to be honest I do believe I have noticed the oil pressure drop at idle at a stop light after bing run fo a while.

Thanks again Dave, I'll t/t ya tomorrow.

Doug Harmon
Nam66/67

Doug, Pat McCarthey is our resident BBC guru!!!! He can handle any and all specific issues that a big block ever dreamed of having!!!!!

some of the steel stamp rockers get valve stem marks worn in the rockers they will go in and out of lash as well as air can get trap in the lifter galley plugs should be drilled to help with air lock .some times on rebuilds the drilled plugs are not used that can help with clicking and look over what dave said as look at the fule pump use a broom handle on the pump to your ear or long screw driver

Thanks Pat!!!!!! U DA MAN!!!!!!!!

Pat, l really thank you and Dave for all your help. Delighted I joined this Forum and plan to be around for a while.
I ran the car this AM as Dave suggested and here are the numbers I came up with (probably way too much info but I felt too much was better than not enough).
Engine start-oil pres immediatly went to 60, when it was about 120 temp I went to 2,000-2,500 RPM oil pressure 80, started the drive did WOT once before at operating temp of 180 and oil pressure bottomed out between the SW at the bottom of the gauge. At 70mph on highway she was 70 psi but settled back to 65 for the remainder of the 15 miles. At every complete stop she was consistant @ 60/65 psi. Stomped her one last time, went to 70 psi and no higher. That really surprised me as when I did WOT when not up to operationg temp it buried the needle. I'll try the fuel pump ASAP.
once again, thanks guy's. I'm sure I'll be back.