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Currently finishing up putting together the engine for the 95 Z28 and have some concern regarding preload on the lifters. Just switched from Crane Gold 1.6 RRs to some Comp Pro Magnum 1.6s due to clearance issues with valve spring retainers. After coming to zero lash, some valves turn with ease and almost no resistance to 3/4 turn and some have what I would consider excessive resistance, with others anywhere in between. I'm sure that all lifters were on the base of cam while adjustment. I had switched from the Crane RRs because they bottomed on the spring retainer after about 1/16 of a turn(self aligning). After the switch to the NSA Pro Magnums, it appears I no longer have that issue, although it's very close. Comp says they are good for 1.540 diameter springs and I'm running Crane dual springs with a diameter of 1.460. Also, my intake valves have been replaced with Manley Pro Flos which has a higher lock position on valve stem. I guess my concern is if this is normal or not? Heads have been milled .017 with stock gasket. Pushrod length is 7.050 checked with comp checker and leaves a good pattern. Any input is appreciated, sorry for the long explanation lol.
sounds like the lifters are "bleeding down" during the valve lash process. As you rotate the engine from one lash to the next valve. Normal
If you are confident you are at zero lash and then go to whatever "preload" you want (1/2 to 1 1/2 turns) the resistance adding the preload will differ. Once the motor starts all lifters will pump up
It is normal when lashing valves where the RR is tight (no movement) immediately after lash to then "loosen" after you have moved on to other valves. This is normal as the non running engine (oil pump) does not keep oil pressure and the lifters bleed off
That's what I was thinking, I just needed someone else to say it for peace of mind purposes, lol. Engine is going in tonight and hopefully that's it and I wont have to tear down again while it's in the car. Fingers crossed she fires tonight, thanks for the response!
Its a great feeling when a new motor you install fires up. Check all connections twice, pull coil wire and crank some until you get oil pressure then start the motor. I like to keep the rpm about 1500-2k rpm. use a washer or something to hold the throttle open at the throttle body to assist in getting great oil pressure in the motor for the first 20 min. Not really a cam break in as roller cams don't need it but more to keep oil pressure up. I look everywhere for leaks and use a IR temp gun to monitor exhaust (headers or manifold) for consistent temps which if one was low would point to that cyl not firing.
After that initial start up and engine is up to temp I shut off and drain oil and cut open filter to see if any unwanted metal in in there. The oil typically will have assembly lube in it also and some minor debris from the build is likely in motor so the oil swap then, IMHO, is a good idea. There is "break in" oil you can use that has a higher zinc content. Joe Gibbs, Kendall and Valvoline VR racing oil are some. New oil and then go and set the rings doing 0-35 mph in low gear and let the engine brake the car down to 5 mph, repeat a few times then increase to 45 mph a few times and then just drive it "normal" (read don't baby it". This accelerate then engine brake loads the piston rings well and makes for good ring seating IMHO. Change oil and filter at 500 mi then just normal oil change intervals after that
06-18-2019, 06:22 PM
