Valve train noise ? missing/backfires now on acceleration

Hello, I need some help with my 1970 GS455. I've owned the car for about 2 yrs and this problem just started. Besides the noise, it now misses and backfires on acceleration.

I've attached some links to some YouTube videos. It sounds to me like the noise is coming from the passenger side valve cover, but its hard to tell.

Here are some of the following TA performance upgrades to the heads before I bought the car:

TA_STAGE_1SE-A Stage 1 SE Aluminum Cylinder Heads
TA_1313 455 Stg 1 & 2 Roller Rockers, 1.65 Ratio
TA_1405 DELPHI HYD. LIFTERS '70/UP
TA_1423-2 5/16" 455 Non-Adjustable Pushrods

Video link to the noise(after its warmed up) :

After reading some other threads about valve train noise, I did record a slow motion video of it at idle with the valve cover off, but the car was cold at the time and the noise to me isn't really present when its cold.
I also didn't see any obvious loose lifters.

Video link to slow motion without valve cover : https://youtu.be/50Ch7RgMxbc

Would doing a compression check on all the cylinders be the next step?

Thanks in advance for any help
Len

 

Was the cam broken in properly?
How much lifter preload? With aluminum heads you need to run more preload. Preload reduces as motor gets warmer.

Sadly now that it is missing and backfiring a lobe or 2 may be flat.

 

The engine upgrades were done several years before I purchased the car, so I can't answer your questions.

 

compression check never hurts. Do it hot with all the plugs out. Check the plugs and see if any are different. You are looking to narrow down which cylinder is missing. Also, you could pull one plug wire at a time, accelerate, do it for all plugs. See if that tells you anything.

 

thanks BQUICK, Bill and Larry for your comments so far.

I was wondering if replacing the TA_1313 Roller Rockers and the TA_1405 Lifters could be considered. I realize this would be quite expensive ($1400) for just these parts. Or, is the consensus these issues are far more likely to be Cam related?
From the literature I got with the car, it looks to have a Comp Cam 96-203-4 (installed in 2007)

https://www.compcams.com/high-energy-218-218-hydraulic-flat-cam-for-buick-400-430-455.html

I realize this is all guess work without tearing it all apart. I'm just trying to tap some of the experience on this forum given the parts involved.
Any help/comments are appreciated.

 

You must do all diagnosis and arrive at a root cause before even thinking of replacing parts.

Devon

 

Agreed.

DO NOT "pull" one plug wire at a time. That makes for an open circuit on the coil for that cylinder's firing. Voltage goes sky-high, very hard on the ignition insulation, including the coil's internal windings insulation.

GROUND the spark for each cylinder in turn. Get eight small nails, blunt the tips so they don't cut the plug-wire or boot. Add a touch of dielectric grease to each. SLIDE the nails BETWEEN the plug wires and the distributor boots, until you feel the nail touch the metal end of the plug wire. With the engine idling, clamp a grounded jumper wire, or touch a grounded incandescent test light to each nail in turn. With a vacuum gauge on manifold vacuum, you'll see how each cylinder drops the vacuum. All cylinders should affect vacuum equally. Cylinders that don't drop the vacuum as much as the others, are weak. Cylinders that don't drop the vacuum at all are dead.



When you're done, you pull the greased nails out, having done zero damage to the insulation of the plug wires.

Thank you.

 

That is a great idea beats trying to pull a wire and have a shock get ya. get your drunk buddies to see if they can touch the pin, their stupid they will do it LOL.

 

He pulled the valve cover and sent a video as well.

 

I know you said it's missing and backfiring but how evident is it? Could it just be something in your head now that you think something is wrong with the engine? My first thought was to pull those accessory belts off the power steering and the alternator and see how it sounds. You could even run without the fan belt for a short time to see (not too long though). That will help eliminate all the other moving parts other than the valvetrain and rotating assembly. I watched your second video a dozen times in extra slow-mo and nothing looked out of place to me... couldn't see the pushrods for #2 and #4 but all the rockers appeared to have the same distance of travel. ... nothing was moving out of sequence to everything else... all 4 hold-down bolts were solid.

 

I think perhaps a dial indicator with a magnetic base is in order. Valve covers off. Rocker shafts off. Don't pull the pushrods yet!

Please report back when you get this far.

Devon

 

It's only making noise when it's hot? Is a sticking valve a possibility?
Missing/backfiring could be unrelated to the valve noise, or could be a symptom of a sticking or burned valve.
A lean mixture or ignition issues could cause those symptoms too.
Put a vacuum gauge on it. That should indicate if there is a valve sealing or sticking issue.

 

LOL, I got zapped by HEI once, DAAAAAAAMN
110 v aint got nothing on 12v ignition

 

My valve train has made noise after warmup for 27 years now and I do not know why it just does. I have adjusted and adjusted those lifters and it is the same, quiet as a mouse on startup and sounds like a solid lifter after warmup. I even use Comp Cams Pro magnum lifters with TA roller rockers.

So I am going to cure that problem by putting in a solid lifter cam this year, if I got to hear the thing make noise, it might as well have a reason.

now your missing issue could be a bad coil or a bad ground that could be causing the coil to put out less juice to the ignition.
it will start backfiring when there is not enough juice to the coil.

 

I've been shocked by 277 and 480 volt circuit. Still don't hurt as much as a lawn mower magneto shock.

 

HAHAHA, yeah a little peepee lawnmower engine with make yah jump outta yer shoes