Dave_J
Well-Known Member
German spec's "Gutentight"
340 issue after camshaft change
- Thread starter Sabremech
- Start date
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German spec's "Gutentight"
Dave_J
Well-Known Member
I think the OP has tightened the rocker down and the lifter piston has moved down past zero lash..... Then when the oil pressurizes the lifter it floats the valves.
With the intake manifold off I always look at the hydrolic lifter's top as I am turning the adjuster down, lifting the pushrod up and down as do this. If the top starts to compress you are at zero lash dry. Go 1/4 turn and LOCK that sucker down, do the next 15.
Fire it up and run the cam in at 2000 RPM for the 20 minutes. Then while still hot and lifters are pumped up, run the lash.
With the intake manifold off I always look at the hydrolic lifter's top as I am turning the adjuster down, lifting the pushrod up and down as do this. If the top starts to compress you are at zero lash dry. Go 1/4 turn and LOCK that sucker down, do the next 15.
Fire it up and run the cam in at 2000 RPM for the 20 minutes. Then while still hot and lifters are pumped up, run the lash.
That is what I was sayin.
Normal position for a hydraulic lifter is past zero lash, so I'm missing your point.
zero lash is when plunger is just barely compressed below the lifter retainer.
do it that way and the valve will be open when the lifter is pressurized.
unless it's a Rhoads or comparable lifter.
No it won't. That's the proper way to set a hydraulic lifter. Think about it. You get the lifter on the base circle, adjust to zero lash and then what? You go PAST ZERO LASH. Right? RIGHT? I usually go 1/4 to 1/2 turn. Some go more. RIGHT?
No zero lash is ZERO. When all of the slack is remove and there's NO lifter preload. THAT'S zero lash.
Phreakish
Well-Known Member
With 60psi of oil pressure, a 3/8 diameter plunger would only have a out 6-7 pounds of force against it, plus the lifter spring. A 1/2 plunger would see about 12 pounds. The small bleed hole and check valve prevents the lifter from collapsing under load during operation.
A properly operating hydraulic lifter cannot open a valve spring under normal conditions. The only way to hang open a valve with a hydraulic lifter is if you float it and the lifter plunger raises above its preload setting. That shouldn't occur at cam break in rpms!
A properly operating hydraulic lifter cannot open a valve spring under normal conditions. The only way to hang open a valve with a hydraulic lifter is if you float it and the lifter plunger raises above its preload setting. That shouldn't occur at cam break in rpms!
I always set preload barely off the retainer
You can do that, but it's not advisable with the little crappy wire plunger retainer. The heavy duty snap ring is much more desirable in that instance.
Dave_J
Well-Known Member
RRR, I HIGHLIGHTED my point above. ;) Click quote to expand.
I always set the lash at 'ZERO' plus a 1/4 turn for start, then after cam break in I do the running lash set and 1/2 turn. Messy but gets them pre set well.
My Eldy NHRA Magnum heads with Chevy rockers:
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I never use a cheap lifter. I take it you never over adjusted a hydraulic lifter on a Chevy, yes you can over adjust and the lifter will keep the valves open when running.Learned that lesson when I was 14 on a 327 in an Impala
Learned that lesson when I was 14 on a 327 in an Impala
Of course if you bottom the plunger out. lol
Dave_J
Well-Known Member
This is what I think the OP did since there was no oil inside the lifter. The lifters have a very light spring under the retainer and its easy to push past that tension and still rotate the pushrod.
On my 410 5.9 build, I took all 16 Hyd Roller lifters apart and emptied the light weight viz oil out and refilled them with 5W30. Made feeling that retainer move much easier.
448Scamp
Running Free
Very unlikely the cam is bad. It’s not degreed so anything that happens after that is still wrong. It’s not hard to set valves. If the OP is struggling with it, he may want to consider hydraulic rockers and be done with it.
Dale Davies
Well-Known Member
Oil pressure can not on its own lift the valve off its seat. If the oil pressure could do that, hydraulic lifters would prevent every engine they are installed in from running. Lifter pump up is caused by high RPM valve float which allows the oil into the lifter and takes a bit of time to bleed down.
Dale Davies
Well-Known Member
When tightening the lash adjuster nut, one finger on the push rod while there is still clearance can rotate the push rod. Do not use a finger and thumb as you can still rotate the push rod while starting to compress the little spring in the lifter. With on finger, as soon as zero lash is obtained the pushrod will stop rotating. Then turn down for the prescribed preload to center the plunger travel.
Dale Davies
Well-Known Member
Just use an oil can
with the pump on it
Use a pump oil can to push oil in the lifter feed hole. Now they are primed. KISS.
Dale Davies
Well-Known Member
Hydraulic rockers??
448Scamp
Running Free
Magnum Rockers for hydraulic cams. Bolt them down. There is no adjusting them, other than perhaps shimming the pedestals up. And I guess you could run adjustable pushrods and run whatever cam if the pr hex adjusters cleared the pushrod guide plates but then you’d be back to the issue at hand
Scody21
Just send it
Lash Caps?
Certainly
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