Okay here it is: I went to the store with my little boy on Sat. to get some gas. The car ran great. I didn't need to touch the carb, or timing. Ran perfect. I didn't get on it b/c I am still in town. Well, I get some gas, and head into another town just b/c the weather is nice. I get 4 miles out and I hear this faint tapping, sounds like a lifter. It turns into a clunking sound real fast. I had already lifted off the gas. I turn around and the car is running rough, but the sound went away. When this happened, I was turning about 2200rpm. I went home with the impression that the sound was a rod knocking. I went as slow as I could, running 1800rpm. I backed in the garage, and got the boy out, then tried to calm down. Our neighbor came over, so I turned the engine over with a push button, we distinguished the sound to the #1 cyl. I pulled the valve cover to find the exhaust rocker was broke right on the fulcrum, and the push rod for the intake was in a "Z" shape. The exhaust push rod was bent also, but not as much. I found that the inner dampner spring on the intake was broke also, along with the valve seal being destroyed. The exhaust side is okay. The spring and seal look new still. I checked clearance and I have .580" between the bottom of the valve retainer, and the top of the valve seal. The springs are set at 1.79" installed, and I have plenty of clearnace for .520" lift. I took the plug out, and it looks normal compared to the others. #7 is a little lighter, but that is the only one. I attributed that to the fact that #5, and #7 fire consecutivly, so it is normal to be a little leaner. I cranked the engine over, and the sound is gone. Now, here is where I need opinions: If the exhaust rocker broke first, do you think enough cyl. pressure might have built up to not let the intake valve open anymore, and bend the push rod, this in turn put enough pressure on the con rod to squish out the oil between the bearing and crank, and let it clatter? The oil pressure never dropped below 50psi, which is where it has been since I first started the enigne. Even when I got home it was still at 50psi at idle, and didn't pulsate at all. I am asking for all opinions, even if they are the ones I don't want to hear.

Thanks,



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Joshua Johnston
1991 Z-28


350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake

 

What rockers and what springs? You've got a lot of lift there for stock Vortec parts.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4. 2.93 limited slip. 2-1/2" cat-back, ZZ3 intake, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 CC system w/'87 LB9 block, ZZ3 cam, ported World 305 heads, Hooker 2055 headers, 3" Catco cat & 3" catback, restalled TC, Spohn SFCs).
57 Bel Air, my 1st car. '66 396, 9.7 CR forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 600 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

 

I'm sorry. These are the H-11 Tool Steel springs that Crane make. The rockers are Proform Roller Tipped rockers. I have just recently heard that these rockers are not that great for large cams. Another question: Does anyone know of a trick way to check for a rod knock, or spun bearing? The sound is all I have ever used, but it doesn't make the sound now.

Thanks,


------------------
Joshua Johnston
1991 Z-28


350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake

 

Anyone please...........



------------------
Joshua Johnston
1991 Z-28


350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake

 

Joshua ... I can't give you any help directly but the following web site has helped me "4. Engine Noise Diagnosis 101".

http://remanufactured-engines.com/page4.htm

Good luck.

 

I suspected you had Proforms, that's why I asked. They're wanna-be's, not good for anything beyond stock lift & RPMs. Ditch 'em and get some real roller rockers.

 

Wait, you said "roller tip". Are you talking stamped steel with a roller tip, or aluminum with roller bearing folcrum and roller tip?

 

five7,
These are chrome moly (stamped) with a roller tip. I am going to get some good aluminum full rollers in a couple weeks.



------------------
Joshua Johnston
1991 Z-28


350, T-5, K&N, Ported Vortec heads, Edelbrock RPM, Holley 750 D.P., HEI, 11.07:1 CR, Comp Cams Roller-.510"/.520"-282*/288* dur., Shorty Headers, Dual 2.5 Exhaust,Dynomax Bullet Mufflers, T&R Motorsports custom air intake

 

Consider the Comp steel rollers. Perhaps a little more expensive, but they won't have life issues like aluminum will.

Personally, I went with Elgin stamped roller tip (Competition Products recommended them over Proform aluminum rollers). Probably should have gone for Comp Magnums, but...