396 experts need help

[Ironangel]

Originally Posted by 69 customcamper

Hey Guys,

I rebuilt my 396 which is a 69 block. Have the Camaro Heads with a Melling MT6 RV Cam. I ended up Putting Poly locks as the replacement Rocker nuts kept coming loose. Factory ones stayed tight. It has 20-50 oil with Zinc additive and 50 PSI oil pressure at idle with a mechanics oil gauge hooked up. Sounds great when cold. Once it hits 185 - 190 degrees , it idles a little rough and sounds like lifters clacking. Done valve adjustment 10 times. I used 3/4 turn. Tried 3 different oils........ If I missed one of the oil plugs for lifter galley on front of motor behind the timing gear , Would I still have 50 psi ? (Doubt it !) . Plugs are staying white so I am thinking it is also lean. Compression is 150 psi all 8 cylinders.......... What else ? Almost ready to yank it and build another motor. I pulled the Bypass valve this morning and it seems good. No gasket although I do not think that would change much other than possibly mixing a tiny bit of unfiltered oil with filtered oil ?

20w-50 is overkill for a fresh rebuild! I'm going to guess your using off the shelf Valvoline VR1 right? Great oil, wrong viscosity! I break all my motors in with 30w only! For two reasons, ring break in and cam break in. Cams only get oiled by the splash and oil slung around by the crank and windage. That's why 2000+ rpm is suggested. The thicker oils wont flow or sling readily until hot and with tight clearances on a fresh rebuild that oil don't get to the critical areas as fast or readily as the thinner oils. Poly locks on a hydraulic cam and lifter is again overkill that can create more problems than they're designed to prevent. Use a quality NEW rocker nut and your done, mark them with a sharpie or paint stick so you can visually verify if they back off or not. A loose poly lock will always back off where a questionable used lock nut wont in many cases. Your not spinning that motor up to 8K and beyond so loose the poly locks! Poly locks also require torqueing to 20 ft lbs, did you torque yours? Use the "EOIC" method to set your valves and give the nuts 1/2 turn. If the valve train is making noise after warm up, you most likely didn't get the rocker nut within the preload range of the lifter. Nothing wrong with adjusting one or two lifters with the motor running but how in the world can you hear the one with the whole gang clattering? What else, oh, drilling a 1/16" hole in each oil galley plug at the front will relieve air trapped in the end of each galley and drip oil on the timing set, BBC's are notorious for oiling issues up front. If Thad Harms and David Vizard drill their plugs, that's good enough for me, I'll spare you the details...I use Valvoline VR1 10w-30 after break in, order it online because the Chinese auto parts stores don't stock it...After re-reading your post, I'm questioning the integrity of the rocker studs...Are they worn out 3/8" studs? New 7'16" Studs are cheap insurance, install them using red permanent Loctite...I have had studs come loose on the older cast iron heads...What is a "Camaro head?" I guess my 69 290 heads are Vette heads? No, they're 3964290's...

[69 customcamper]

Well turn out I had a mess. I took things apart again and wonder if this was the case the first time and I just did not notice it ....... 5 Broken valves springs. Broken on the outter spring so the valves were still closing. Also noticed the Valve guides were too loose. I bought these heads ready to go from someone on ebay. They were beautifully cleaned and had all new hardware. Crappy job ! So I am getting new guides and cleaning them up again and getting the correct springs for MTC6 Melling Camshaft. I am thinking they were not the right springs. I should have looked closer but I have never had a broken spring in all my years of automotive since 1992. I have probably worked on 30 different engines of various types LOL. Oh also the valves were all Snow white on the bottom. Lean condition........

Mike

[69 customcamper]

Originally Posted by Ironangel

20w-50 is overkill for a fresh rebuild! I'm going to guess your using off the shelf Valvoline VR1 right? Great oil, wrong viscosity! I break all my motors in with 30w only! For two reasons, ring break in and cam break in. Cams only get oiled by the splash and oil slung around by the crank and windage. That's why 2000+ rpm is suggested. The thicker oils wont flow or sling readily until hot and with tight clearances on a fresh rebuild that oil don't get to the critical areas as fast or readily as the thinner oils. Poly locks on a hydraulic cam and lifter is again overkill that can create more problems than they're designed to prevent. Use a quality NEW rocker nut and your done, mark them with a sharpie or paint stick so you can visually verify if they back off or not. A loose poly lock will always back off where a questionable used lock nut wont in many cases. Your not spinning that motor up to 8K and beyond so loose the poly locks! Poly locks also require torqueing to 20 ft lbs, did you torque yours? Use the "EOIC" method to set your valves and give the nuts 1/2 turn. If the valve train is making noise after warm up, you most likely didn't get the rocker nut within the preload range of the lifter. Nothing wrong with adjusting one or two lifters with the motor running but how in the world can you hear the one with the whole gang clattering? What else, oh, drilling a 1/16" hole in each oil galley plug at the front will relieve air trapped in the end of each galley and drip oil on the timing set, BBC's are notorious for oiling issues up front. If Thad Harms and David Vizard drill their plugs, that's good enough for me, I'll spare you the details...I use Valvoline VR1 10w-30 after break in, order it online because the Chinese auto parts stores don't stock it...After re-reading your post, I'm questioning the integrity of the rocker studs...Are they worn out 3/8" studs? New 7'16" Studs are cheap insurance, install them using red permanent Loctite...I have had studs come loose on the older cast iron heads...What is a "Camaro head?" I guess my 69 290 heads are Vette heads? No, they're 3964290's...

Nobody seems to make a quality rocker nut anymore. I tried a few brands , all light weight chinese junk even in a sealed power or Melling box. I have new 7/16 ARP studs on it. Pulled the cam and all lobes still at new spec. Going to put new lifters again with the rebuilt heads and new fluids with zinc additive. Will get 30 weight as you suggest . 10w 30 after that . I used the 20-50 out of desperation after trying 10-30 first than 5-30 and nothing really changing. Will also drill the holes in the plugs up front. I heard that GM had a bulletin for this at one time even .

[69 customcamper]

Got it all back together with the correct valve springs and sleeved valve guides so everything is tight. Not getting enough oil to driver side valve train. It chatters . Oil pressure is 50 psi cold at idle. I just realized something......... The HEI distributors I have been using do not have the 3rd ring up high on the shaft like the original points type distributor I had. Could this be letting oil out of the galley ??

[AussieinNC]

Please post a pic of the shaft where you believe ye 3rd O ring is located....

The lower section of the distributor body is a slip fit into the bore above the cam. As the engine heats up, the aluminum body of the distributor expands, closing up the clearances.

Question...when you rebuilt the engine...did you drill small holes in the plugs that go into the front of the oil galleries?

The holes, one in center of each plug, are 1/16" usually...to allow trapped air out of the galleries....air lock is a common issue with BBC engines....

[PGSigns]

I would put a cam in it. You will be on lifter set number 3. The cam stands little chance of survival. The new cam and new lifters need to be broke in together. You cant mix the order if you take the lifters out for some reason. In 45 years I have not seen good results with a used cam and new lifters. After you head experience I would review your entire build.
Jimmy