Technical Fresh Rebuild Clacking

Hello!

I just got my 1966 Buick Special Deluxe Hardtop with 4.9 300 v8 on the road after getting the motor rebuilt.
Parked For 45 Years: 1966 Buick SkylarkBarn Findshttps://barnfinds.com › 1966-buick-skylark-barn-find
After setting the timing way wrong and driving a few blocks to the muffler shop, it is clacking from the passenger side of the motor. I hear it when I jab the throttle while cruising or at about half throttle or more. I reset the timing confirmed good now and the clacking remains.

After reading some posts here, I gather detonation is bad for the top of the piston and ring lands but that's about the only damage it can cause... my gut says it's not detonation I'm hearing but something mechanical. Could my machine shop be to blame.

Should I pull off the intake and verify if the lifters are good? Call the engine builder? The pushrods are all straight except the ball end of one has a circular score mark. I have break in fluid in there now, a buddy of mine suggested a lifter could be empty... would filling up with the 20w50 I plan to run do anything to fill a lifter or is that something I have to do manually?

I appreciate any suggestions y'all..

 

You sure it isn't an exhaust leak on the passenger side?

 

or an exhast pipe hitting the frame or floor? that can and will sound like a knock in the motor

 

The 2 comments above are in line, I'd check them. However, it sounds like you really don't know what an internal problem would sound like even if you could pinpoint where it's coming from. Your best insurance and for your investment is go talk to the motor builder and ask him to come listen. He will know if it's his problem of something you did or didn't do right. With his input you will go straight to the issue and take care of it. Driving the car a few blocks to a muffler shop with the timing a little off isn't going to cause a terminal inside issue but left unattended it darn well could. Your Ear and best Quess isn't going to fix anything. Protect your investment, do the right thing.

 

I checked the manifold bolts are tight... but I didn't look at the new exhaust.

So it's probably not mechanical huh

That's what I'll do, I need the right set of ears on this sound..

 

You're still guessing.

 

If the engine has a heat riser valve on the RH side exhaust, when they are worn they can make a sound that sounds a lot like something bad happening inside the engine. With a good pair of welding gloves, holding the valve weight usually will quiet the noise enough to tell if that's the problem or not.

 

I always start at the newest stuff I put on the car and work backward when chasing an issue. "New Exhaust" doesn't mean great exhaust.

 

I did't put the heat rise valve back on..
How overpriced the exhaust was, I couldn't imagine there could be a leak.. how silly of me!

 

How did you determine that the pushrods are straight and one is scored ? Not a put down, but from your descriptions of the problem it appears you have very limited experience with mechanics. If you have loosened all the rocker arms and removed the pushrods, you probably need to get someone to show you how to reassemble them, because you have to rotate the engine to a certain (and different) point when reinstalling. I would check your oil to see that there are no metal particles in it if you are breaking in an engine...especially if you replaced the lifters. The "clacking" noise could simply have been a loose rocker arm or a stuck lifter......or as bad as a ruined camshaft during the break in process.

 

If the noise only occurs when you jab the throttle or at half throttle or more under load, lifters are not the problem. Exhaust leak is highly likely.

 

I am way past being offended by constructive criticism haha!
You guys rock, this is exactly the type of info I was looking for.

If an exhaust leak is highly likely, I will hunt it down.

If all else fails, I'll get some expert ears on it

 

We can refer to possibilities but get someones ear on it.
The builder is the man.
If timing is ever off, that should be dealt before mufflers IMHO

 

One side of the heat riser is flat where is seals to the manifold, the other side is relieved to fit the donut gasket. With it the donut has no place to seat on the manifold. Reinstall it with a flat gasket and new donut.

 

Maybe make a video so you can play the sound. Host it on YouTube and paste the link here.

 

After you installed the engine, what break-in procedure did you do before you drove it to the exhaust shop?

 

I think this is the solution... Now, let me see if I can find it!

 

I have been following the word of the 1966 Chassis manual off teambuick website. I did pre-timing based on the manual finding cylinder 1 etc. and it fired up, held it at 2000 rpm for about 20 minutes. I believe break in was successful..

Now that I think about it.. I first heard the sound on the way home from the muffler shop...

Will report back once I get the heat rise valve back on with proper gaskets.

 

A good exhaust guy shouldn’t have left a gasket out of the manifold to pipe connection, even if it wasn’t as the factory designed it. If that seems to be the problem, they should fix it for free.

 

Exhaust leaks will leave a grey sooty residue, look around for that. You could have an undetected crack in the exhaust manifold. This is how I found a few of them.

 

What you described as "clacking" reminded me of the sound I was hearing on the fresh motor in the car I was finishing. Check to insure a rocker adjusting nut hasn't backed off allowing excess clearance. In my case it was a flat cam I hope you don't have the same issue.

 

It's cheap insurance to unbolt the exhaust manifold and look at the gasket that goes between it and the heads. It will reveal if there's a leak there as you'll see black sooty areas migrating out from the exhaust ports.
I've seen guys pull valve covers, and even swap out lifters because they heard a "lifter rattle" and it was an exhaust gasket.
As for the choice of 20w-50w oil after breakin, I'm wondering why you want oil that heavy? That's maybe OK for hi performance engines that see heavy, high rpm runs, but for a daily driver fresh engine it seems a bit much. Did your engine builder recommend this weight oil?

 

Check for loose pushrods. I did a motor in a truck years back, ran great. Sent in for exhaust, ran like shit and noisy when it came back. Turns out they must have been testing out my glass packs and bent 3 pushrods on an over rev.
Couldn't prove it and they wouldn't admit it.

 

If an engine is built right, why would revving it up bend a pushrod?

 

I'd be looking at lifters and wiped out cam lobes

 

Where are you located? Maybe there's a HAMB member near you who could lend an ear.

 

Probably trying to get an alleged " high zinc oil"

 

A cracked flex plate can make some strange noises.

 

Usually they make noise when there isn't a load on the engine as does loose torque converter bolts. I got the Olds 350 R that I ran in my 51 Merc for free along with the 60 something square truck it was in because it had a knock. The knock was loose converter bolts.

Now with that behind, what I intended to suggest is go to the parts house or harbor freight and buy a Mechanics stethoscope. They work real well to isolate mechanical noises to a certain area/spot. Usually under a well spent 10 bucks.

 

Never a good idea to begin troubleshooting by looking at the most expensive repairs! It's just common sense troubleshooting to begin with the easiest, least expensive problems, and work your way up. Starting with things like cams that can go flat, or other expensive, time consuming fixes usually results in a lot of wasted time and money.