Rebuilt 263 w/ 70psi compression and 10In.Hg vacuum. What to do/test next?

[jaye]

I had a Ford 302 with similar issues & it turned out to be a bent flap on the bottom of the carb which prevented it closing enough to get the idle down.

[Jenz38]

Thank you Jenz38
Your advice to " give the hydraulics zero lash at running engine , check it by your ears" to confirm would be:
Start with warm running engine then back off (currently 1/8 turn) pre-load until I hear "clicking" then tighten (give "pre-load") slowly until "clicking" just goes away?(zero lash). You then say "tighten after zero" to mean that's It, tighten lock nut at point "clicking" goes away?

Yes, Correct..
In my case ,i never use a vacuum gauge...😉..more than closed valves ,new Pistonrings, a sealed intake and a correct timing (chain)isn't possible.
The less pressure/vacuum, I would say ,comes from the fresh,not break in , new (rough) stuff in your motor,that's all "brake" down a smooth idle.
Drive it and you will feel it runs smoother and smoother the next k miles....😊

[mavrick]

Yes, Correct..
In my case ,i never use a vacuum gauge...😉..more than closed valves ,new Pistonrings, a sealed intake and a correct timing (chain)isn't possible.
The less pressure/vacuum, I would say ,comes from the fresh,not break in , new (rough) stuff in your motor,that's all "brake" down a smooth idle.
Drive it and you will feel it runs smoother and smoother the next k miles....😊

Did you consider that you may have a solid lifter cam? if you do, it won't run right without 15 thou clearance..Dave

[Jenz38]

Dave, If I understand you right..yes, of course, i drive with a clearance (best results with .10) with my solids.
But for finding the problem at ( Joe's) hydraulics, I would try it with zero lash at running engine = lifter filled up with oil under pressure and you can see if they work all like each other ..
or with a couple of its is "something" wrong or different...may be they're leaky.😉

[mavrick]

Dave, If I understand you right..yes, of course, i drive with a clearance (best results with .10) with my solids.
But for finding the problem at ( Joe's) hydraulics, I would try it with zero lash at running engine = lifter filled up with oil under pressure and you can see if they work all like each other ..
or with a couple of its is "something" wrong or different...may be they're leaky.😉

If the cam is intended to be used with solid lifters, it will have "clearance ramps" to quiet the operation. I don't remember the clearance but you must have it for the valve events to be correct. After looking in the manual, I see the valve lash is .015"...Dave

[Jenz38]

Yes,you're right, Dave ...

[joe28704]

The basic mystery this engine faces with these NEW HYDRAULIC lifters is as follows:
LIFTER PRELOAD In.Hg VACUUM
2 Turns (per book).........6-7 (70 psi compression)
1 Turn ........................10-11
Zero lash(cold).............13-14
.008 Lash (cold).............17-18 (125 psi compression)
Things I have checked:
Called Cam grinder to inquire about records kept of what grind it got. Shop indicated marks on cam called for a hydraulic grind, that is what they say they gave it.( I sent it in for resurfacing given the new "Chinese" lifters i was receiving from Packard Industries)

Checked valve springs forces on test fixture. All on the low side but still within specs.All my engine tests are around Idle.
Changed oil from 15W-40 to 5W-20. No change.
Checked timing with dial indicator on valve spring cap per book. All is as should be.
Drove car for two hours to rule out rings not setting.
Rockers are visibly supplying oil quite well to push
rods, no air in oil.

One observation I made was the internal design of check valve system inside the new lifters;
My new lifters have a check DISC with check disc spring that provides INSTANT/CONSTANT flow check from lower chamber to upper chamber as lifter body rises up toward plunger so that lifter has no "lift loss" as REQUIRED and designed into the original design Check BALL system lifters.
Original design lifters have the check BALL travel upwards .004" to .008" prior to checking flow and thus shortening overall length of lifter a designed .002" to .003". (All this is in the 52' Buick Shop Manual)
When original design lifter then rides up the lobe and back down again it will be the valve that seats first (since lifter has "shrunk") then the Large lifter spring expands the valve body against the cam lobe and the cycle starts over again. If lifter stays same height or expands (pump-up) then valves wont seat displaying the low vacuum and compression I am seeing.

If no "LIFT LOSS" is available by design with the check DISC and there is no designed or otherwise Lift Loss by virtue of "leakdown" created by machined clearance between plunger OD and body ID then the only thing these new lifters can do is "Pump-up".

If anyone can walk me thru the dynamics of how a stock (check BALL) hydraulic lifter would act under the influence of a mechanical grind cam lobe I would love to hear about it as its past my pay grade to analyse it.

What I'm ultimately trying to do is figure out why vacuum readings behave the way they do by modifying just one variable and that is the Pre-load/lash.

The folks I bought them from have been exceptionally understanding of this condition and have assigned an experienced person to help me figure this out.
I have followed thru with every conceivable test he has come up with of my engine that you can imagine and so far nothing conclusive. He is a little skeptical (But wonderfully open minded) of my theory of why this is occurring (Improperly designed lifters/Disc design) I think because they are not hearing about this problem from other people they have sold these lifters to (?). I must say I'm a little disappointed that not one of the major Buick engine parts suppliers (yes all the big ones we know) I have contacted were aware of the internal design of the Chinese lifters they are reselling they also have no "specs" on them in regard to "preload", "lift Loss" or "leak down" rate, blueprints, nothing.

Where this stands now is that I was invited to send them back and they will see if they can find a "rebuilt" set or some other thing they can come up with.(?) I'm hesitant to purchase a new set from anyone else because I'm convinced all current new lifters sold in the USA are from a single source in China,(same Factory) and I don't get a nice fuzzy feeling when I call and bring this technical issue up. To a great extent I don't blame them since they don't have my engine in front of them and I could be some guy not being fully aware of my engine elements. HELLO!( I once put brake pads on backwards!)
I am very grateful I'm dealing with a very understanding and concerned person I have been assigned to and communication is very very good. He Really cares and that means more to me than the cost of the lifters.
If anyone has a source for lifters they are confident of I would love to hear about them. NOS?!

I'll keep you posted when I hear back from them.

P.S. Maurick, Thank you for the Comment about the cam profile. Short of taking it out and re-testing I can just go by the records of the Cam grinder.
(cam lobe appex did not "look pointy" like a mechanical lobe might upon return from the shop, that's my two cents)

[mavrick]

[QUOTE=joe28704;103388]The basic mystery this engine faces with these NEW HYDRAULIC lifters is as follows:
LIFTER PRELOAD In.Hg VACUUM
2 Turns (per book).........6 What you can do is set them all at .015 n see how it runs, if good, you can probably leave the lifters in and just drive. IF it is a solid lifter cam, the valves should be fairly quiet at .015", maybe a little tighter. Dave

[joe28704]

Sorry Mavrick but "you can probably leave the lifters in and just drive" is not a sufficient answer for me.
I wont run hydraulic lifters with any lash. (Defeats the purpose plus possible engine damage if clips come off.)
I still think I got a set of poorly calibrated lifters that just pump up and become solid thus not allowing valves to seat.
But that is just a thought unless someone else has a clue to this mystery.
Thank you.