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#1
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Lifter troubles (a bit long)
Just before I shut it down and escaped the winter for a few months, my engine developed a problem. I think something is going on with the lifters. They are 1980's era VL 11 from HO Racing, along with the HC 02 - HO 744 HL cam. Modern HS 1.65 rockers. ~ 520 @ valve.
Luckily it happened just as I pulled into my garage. Just as I shut it off I heard a tap.... tap..tap tap. I restared it and it went tap.. tap..tap.tap tapitty tapitty tappity. Shut it down. Sounded like it was coming from the top of the right side of the engine as opposed to a heavy knock from the bottom (rods). I took the valve cover off to check the rocker arms. A couple of them felt loose and I was able to depress the push rod ends a fair bit. I thought, crap, cam lobes. Today I started to get on top of it. Exposed the lifter galley. I randomly checked the lifers, not all. For example, I brought #8 to tdc (it was closest). Both lifters on base circle. The exhaust lifter was hard and I could not depress it. The intake lifter was soft and I was able to depress it. I checked others that were on or close to the base circle. Same results. Some were hard, others were able to be depressed, some easier than others. Of those some depressed farther. I did not make notes as to which, just trying to find a commonality. I also rotated the engine to see what the lifters do on the nose. Again, some of them the plungers depressed a significant amount while others only slightly. I then spun the oil pump up with the pre lube tool. Steady 68 psi. The ones on the nose were rock hard to begin with. The ones close to base circle became hard but began to soften as they bled down. Some stayed hard, others I was able to depress, some easier & farther, others stiff & only a bit. Again, I did not take notes, nor did I check each lifter on base and nose. Just trying to see if all acted the same. When I was running the oil pump I saw oil exiting the lifter bores, but I got none to the top. Ran the pump three or four times, longest maybe 30 or so seconds. And, the cam looked good to me. Pics if required. BTW I tried the plug in the spark plug hole to find TDC. Worked well for me on my 461 in AZ. This 400 here at home - nada. Thanks in advance for any info. Frank M.
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Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ |
#2
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When you run the pump is one bank of the motor getting oil to the top of the push Rods and one is not?
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I do stuff for reasons. |
#3
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Neither bank is getting oil to the top. If the front galley plugs have popped out would I still be able to get oil pressure by the dizzy?
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Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ |
#4
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Lifter leak down is rated in seconds.
The time it takes to get a valve cover off is enough for rocker arms to be loose. If the check valve on the bottom of the lifter plunger isn't spring loaded... You would have to push down on the push rod really fast for the lifter to hold. I suspect those lifters have metered oil flow to the push rod. Combine that with after market rocker arms... Oil flow to the top could be slim to none without spinning the engine over. Metering disc, under the push rod cup, needs slack (lifter on base circle) to get good oil flow up the push rod. Squirt hole in factory rocker arms lined up with the push rod hole when valves were closed (lifter on base circle). Where squirt hole in most roller rockers lines up with the push rod hole at half valve lift. Take your spark plugs out, get your primer running, spin the engine with the starter and see if things don't change. AND cap the fuel line off before you spin the engine over. Clay |
#5
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The instruction called for 1/8 turn preload for a street engine. I don't know how much distance that is. Is there a chance I lost the preload because of aluminum head expansion? I took the lifters out of #6 as they were on base. Then I bumped the the oil pump for about a sec. Got a mini geyser. Oil supply is not a problem.
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Frank M. 75 Firebird 68 Firebird 400 RAIII 66 Chevy II 461 Pontiac in AZ |
#6
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When you prime the engine,start at top dead center on number one and prime,make a 360 turn on the crank,prime again,do it 2 more times and you should have had oil to the top of all rockers.Tom
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#7
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‘The instruction called for 1/8 turn preload for a street engine. I don't know how much distance that is. Is there a chance I lost the preload because of aluminum head expansion?‘
In addition to aluminum expansion, rocker studs on modern aluminum heads likely have a finer thread than factory, giving you less preload per ‘turn’ FWIW - 1/8 turn is very little preload. Cliff’s method of determining total lifter travel, then backing pre-load out from the bottom to 1/2 of travel may help here? |
#8
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Quote:
The pressures you are seeing with the priming tool would indicate that the front plugs are intact. Good luck! |
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