clamorous clatter with Yella Terra rockers. suggestions?

[falcon fanatic]

So, my engine runs great and makes decent power, but it raises a clamourous racket above about 3500 rpm at full throttle. At first I though it was the normal behaviour of an old pushrod engine, but it does sound especially busy. Then it ocurred to me that it might be very dramatic detonation that I just didn't recognize because I've never heard it like that before. Now, after retarding initial all the way to 4 degrees with no change, I am back at about 12* initial and it sounds the same, and no pinging anywhere. AFR is about a steady 13.5:1 at WOT all the way to the shift. Any suggestions why my engine could be so darn noisey, or is it just the way they are.

FYI this is a 200, with full roller rockers, stock cam, stock bottom end, cc 51.5 and deck is around .025 with a fel-pro gasket (cr about 8.7:1 ??). DUI ignition with 24* advance at 3k, weber 38/38 direct mount on ported head with the big valves, 302 springs.

 

[page62]

Do you have hood pad insulation? Firewall insulation? Solid or hydraulic cam?

Roller rockers can be clamorous, especially in these old tin cans...oops, I mean classic steel automobiles...

 

[falcon fanatic]

no, no (except for stock), and hydraulic cam. And yes, i do believe the noise coincides with the installation of the new head with...roller rockers. definite possibility. I did, in fact, re-adust my rockers after initial drives because I suspected they where loose and making noise. But they weren't. loose, that is.

 

[Bort62]

Well, detonation is possible, but the fact that you pulled so much timing w/o effect points away from that.

The rockers could certainly do it. Im not familiar w/ the RR on your engine, so I can't comment specifically. A few rockers slightly out of adjustment will make one hell of a racket at high rpm.

 

[wsa111]

Your WOT a/f ratio at 13.5 is too lean,. You should be 12.8-13.1 for best power on a NA engine.
The too lean full throttle mixture will cause detonation, richen it up & use 93 octane fuel & that should fix your problem. Bill

 

[falcon fanatic]

Hmmm. Now the complex jetting question. I have between 12.5 to 14:1 most of the time at cruise. Be that at 25 mph or 75 mph. Thus I was going to step up a size on my air corrector jet for a leaner mix at high rpms, and one size smaller on the idle jet for a leaner mixture at low speeds. But, I want to bump up the fuel enrichment circuit at WOT. How do I do that?

 

[falcon fanatic]

So, after some testing, a plug reading, etc, etc, the noise point directly at the Yella Terra rockers. Why would these be so noisy? what can I do about it? It really sound like they are beating themselves to death in there. Just did an inspection/ adjustment and everything looked fine. They do have considerable side play, but always have. I have 302 springs, but that hardly seems like grounds for excessive noise, they are quite tame by most standards. Head is milled. not sure how much, but resulting in 51.5cc chambers, which seems pretty common around these parts.

 

[Bort62]

Well, I'm not familiar w/ how the yella terra rockers mount, but typically noisy rockers is due to loose tolerances.

Are you sure you don't just have them too loose?

 

[wsa111]

Do you have the V8 oiling lifters for the small block ford??
I ran into some mechanical interference when bolting down the individual rocker arm fasterers with the cylinder head & had to shorten the rocker arm bolt or bolts, the bolts protrude through the mounting bars & interfere with the head casting.
My yella-terra's are a little louder than stock.
I rev my engine to 6000 rpms for shift points & hear no abnormal noise.
Are your pushrods hitting the cylinder head??
Do you have proper oil from the oil through pushrods to lubricate the valave train??
Let me know what you find. Bill

 

[falcon fanatic]

Bill,
I got the complete package from Classic Inlines which included lifters and pushrods. I have to assume they where the correct lifters, and the pushrods definitely had oil passages. Also, there is plenty of oil in and around and on the valvetrain when I remove the cover. I can only conclude that I have the right lifters. Also, the engine is smooth and quiet and wonderful up to about 4k, then it gets noisy, so I don't believe the pushrods are hitting anything.

Bort,
These do fit kinda loose on their shafts in terms of end play, but not in terms of bearing play. I have them adusted as per specs with 1/2 turn beyond when you can no loner spin the pushrod with your fingers.

I did read somewhere on the interweb, source of all information, that noisy valvetrain at high revs can be caused by incorrect pushrod length, particularly with milled heads. however, 4k is not exactly high revs, and my head is not milled all that much. I wish thre was someone else who could listen to this and give an opinion :roll: :roll:

 

[Bort62]

Fire it up without the VC on. You will be able to see if one is loose.

I would no suggest revving the crap out of it, tho - Will make a mess.

The 1/2 turn past where you can spin the pushrod depends on the valves both being full closed at that point, and is pretty easy to screw up.

rotate the engine by hand and check each rocker to make sure it stays tight the entire time.

A loose rocker is pretty easy to find.

 

[addo]

Is there coil bind with the heavier springs and increased rocker ratio?

 

[falcon fanatic]

Thanks for the ideas.

I dunno bort, I've done hundreds of valve adjustments in my time and I usually get them right, and I know my TDC marks are spot on, but then again, I've also learned that I make my fair share of mistakes. And contrary to popular belief, one's fair share of mistakes is pretty substantial

Addo, with a stock cam? I dont think so. Nevertheless, I think I will both do a couple of full crank rotations and check the springs and pushrods, and then I'll run the engine with the VC off. I haven't wanted to do that due to the oil-through pushrods which, I asume, will make a colossal mess. At this point, though, I'm stumped so...

 

[wsa111]

I thought about this & you said the noise only occurs at full throttle.

The only thing different at full throttle is more pressure to open the exhaust valve, otherwise the valve train is out of the equation.
The valve train noise only might vary at different rpms under WOT or not.

Have you thought about a cracked flexplate or even balance weights on the converter hitting the bell housing when the flexplate flexes.

Or the converter bolts hitting the starter housing??? Billl