Big Block ticking? Flat tappet cam. Normal?

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Kent mosby

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This is a video of my 512 rb at idle 950 rpms or so. I switched to 1.6 ratio rockers over the winter and have not driven it much since. Cam card calls for .016 and .018 valve lash. I set it at .010 and .012 cold and have not checked it since. I know that the flat tappet cam will have some noise and my hot rodding neighbor says that it is normal. I can find no exhaust leaks and it increases with rpms.
What do you think? Anything to check when I double check the valve lash hot later on. It seems to run fine, but with over 500 ci, it is hard to tell.

 
Does not sound good at all. Definitely dead on a cylinder. Make sure your adjusting them at the correct time. Valves are to loud


The proper way to adjust them is

(When the exhaust starts to open adjust the intake valve on that cylinder)

(When the intake is fully open and just started to close adjust the exhaust on that cylinder)


Here is an engine with solid a lift cam. A slight whirring noise is all you here under the hood.


 
Does not sound good at all. Definitely dead on a cylinder. Make sure your adjusting them at the correct time. Valves are to loud


The proper way to adjust them is

(When the exhaust starts to open adjust the intake valve on that cylinder)

(When the intake is fully open and just started to close adjust the exhaust on that cylinder)


Here is an engine with solid a lift cam. A slight whirring noise is all you here under the hood.





I will check them in a couple weeks. The cam was ground for 1.5 lifters and I now have 1.6 ratio lifters. Is that a factor for increased noise? When you say "dead on a cylinder", what does that mean? Cause? thanks
 
That engine definitely does not sound happy. And I agree, sounds like it's missing on one cylinder at least.
 
You can hear it clear as day not firing on all 8 cylinders. I wouldn't start it up until you check what the problem is . Take the valve covers off and the spark plugs out. Make sure you have no tight or loose rockers. Then do a compression check on all cylinders.

header leaks at the head can sound like a lifter tap. But a dead cylinder and a tap I would question.
 
Well, something to think about here. The center valve rail hold down was stripped out.

144891F5-2F0F-498E-B59E-02DD0F9BA6F1.jpeg


The motor is about 125 degrees now and I can touch the heads without a problem, warm but not hot. Yet the valve lash was at .018 on all intakes and .020-.021 on all exhaust. They should be .016 And .018 hot. So they are really loose. Any danger running like that for a cruise tonight. I replaced the stripped bolt on the hold down
 
Well, something to think about here. The center valve rail hold down was stripped out.

View attachment 1715943333

The motor is about 125 degrees now and I can touch the heads without a problem, warm but not hot. Yet the valve lash was at .018 on all intakes and .020-.021 on all exhaust. They should be .016 And .018 hot. So they are really loose. Any danger running like that for a cruise tonight. I replaced the stripped bolt on the hold down
I would convert to studs if I were you.
 
Btw. When I used the stethoscope the tick was at the area of the loose hold down.
 
You could do a quick Test to determine if it is a valve lash adjustment problem or a valve train geometry problem.

Take one bank and set all the valves to zero lash. Run it for 30 seconds and see if that bank goes quiet.

If it still is making noise then it's probably a geometry problem with your 1.6 rocker arms.

Reset the test bank, back to the proper Valve Lash after the test.
 
What was done to fix/repair those stripped threads?

Personally, I want to see more thread engagement than that for rocker shaft hold downs.
 
Later on I will put studs in and possibly helicoil inserts.

@George Jets i will adjust the valves at the same time as installing studs. Probably a couple weeks out.

After fixing that hold down, the tick that was loudest at cylinder 5 went away and it is now equal everywhere on the valve covers when using the stethoscope. Tomorrow I will measure the valves when the motor is completely cooled and compare. Depending on what I find when cool, I may adjust before getting studs.
 
The stripped hold down is a big contributor. I agree about the stud conversion.
 
With Father's day weekend I might not get to this, but I will redo the valve lash and check it out. I was worried about dead cylinder and wiping a lobe on the cam. But since the lash specs are close, probably not the case. Unless they all wore equally after less than 100 miles on the new rockers. I will post an update when I find something.
 
How do you plan on handling the stripped rocker shaft hole? I honestly see no other way around it than to pull the heads and let a competent machine shop do them all so the holes will have good heli coils and all be indexed correctly. There's no way I would try it with the heads on the engine. Just my personal opinion.
 
How do you plan on handling the stripped rocker shaft hole? I honestly see no other way around it than to pull the heads and let a competent machine shop do them all so the holes will have good heli coils and all be indexed correctly. There's no way I would try it with the heads on the engine. Just my personal opinion.

He probably just put in a longer bolt for now . . .

Let's see, those are aftermarket Aluminum Heads, so those rocker shaft mount threads are going to be a lot weaker that the stock cast iron heads rocker shaft mount threads.
 
When I built a 440 last year that had alum heads, I used studs for the rocker shaft retention. I would switch to studs before doing anything else. Make sure the studs bottom out, that way you use all the threads to better distribute the load. You might get lucky with the stripped thread........if there is enough thread left.
Here is how to do it: remove the rockers from the shaft. Loctite all the studs & screw them in. Refit the shaft & fit nuts & tighten up, but just snug. The idea is to let the Loctite set under the working load it will see. Make sure when making the studs, you leave room for TWO nuts. After the Loctite has set, refit rockers + shafts. Use ONE nut to tighten the hold downs. The shafts sit in a cradle & are well supported, so no need to go overboard when tightening. Just snug. Don't forget with a hollow shaft, you get to a point where you are squashing the shaft & not tightening anymore. Use the other nut as a lock nut to prevent loosening off.

No need to go through the back breaking adjustment procedure above for setting lash. This is a Mopar procedure that allows you to adjust 16 valves for just two crank rotations. Adjust 2 intake, & 2 exh at each location.

#1 TDC: 2,7; 4,8
rotate 180 CW: 1,8; 3,6
rotate 180 CW [ now #6 TDC ]: 3,4; 5,7
rotate 180 CW:5,6; 1,2

Done!
 
Yall need to really look at how much aluminum is in that bolt Kent posted. He's NOT going to save that hole. Ain't happenin. Heli coil is all that will fix it.
 
If your squashing your rocker shaft, then your over tightening it.
 
.........Any danger running like that for a cruise tonight. I replaced the stripped bolt on the hold down
IMO, you'll likely pull the rest the threads out of that bolt hole if you don't fix it correctly. I'd also go back through all the hold down bolts. Make sure to have at least 1-1/2 the bolt diameter thread engagement while still meeting torque and not bottoming out.
 
I have a stud kit on the way. If I do not have threads left, I will have them repaired.
When I built a 440 last year that had alum heads, I used studs for the rocker shaft retention. I would switch to studs before doing anything else. Make sure the studs bottom out, that way you use all the threads to better distribute the load. You might get lucky with the stripped thread........if there is enough thread left.
Here is how to do it: remove the rockers from the shaft. Loctite all the studs & screw them in. Refit the shaft & fit nuts & tighten up, but just snug. The idea is to let the Loctite set under the working load it will see. Make sure when making the studs, you leave room for TWO nuts. After the Loctite has set, refit rockers + shafts. Use ONE nut to tighten the hold downs. The shafts sit in a cradle & are well supported, so no need to go overboard when tightening. Just snug. Don't forget with a hollow shaft, you get to a point where you are squashing the shaft & not tightening anymore. Use the other nut as a lock nut to prevent loosening off.

No need to go through the back breaking adjustment procedure above for setting lash. This is a Mopar procedure that allows you to adjust 16 valves for just two crank rotations. Adjust 2 intake, & 2 exh at each location.

#1 TDC: 2,7; 4,8
rotate 180 CW: 1,8; 3,6
rotate 180 CW [ now #6 TDC ]: 3,4; 5,7
rotate 180 CW:5,6; 1,2

Done!


IMG_2562.jpg

This is my lash guide. 2 rotations also. numbers in pencil are after inspecting with temp at 125 or so.
I have a stud kit on the way. If I do not have threads left, I will have them repaired. I will also check the heads for complete thread depth, I can flat bottom tap if needed for extra depth, not drilling deeper, just tapping to gain extra thread. Trick flow wants .600 in thread and torque to 40 lbs. I will double check that.

Thanks for all the help everyone.
 
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