[BogiesAnnex1]

30 degrees of advance without vacuum connected seems like a lot for this cam.

Clacking noise isn’t good, one has to wonder why rockers came loose. Choices could be the nut wasn’t locked down, pistons hit open valves, Vortec heads weren't clearance enough for the valve lift colliding retainer to guide seal or guide itself, lobes and or lifters going away.

Up and down idle can be a carb or ignition timing issue.

Black fouled plugs is usually a fueling issue of too much but backfiring through the intake is mostly a sign of a lean mixture, then again not getting to operated temp snd staying there a while can cause this as well.

You said the cam is advanced if so by how much?

A Holley 600 vac secondary Holley is going to want a lot of throttle opening to get enough air to idle, this is going to get into the transition circuit so it will be running along with the idle circuit which is going to mess up the idle and transition to main metering in fact the open throttles might also trigger the mains making for an extremely rich idle.

Lots of things to check out unfortunately.

Bogie

 

[BogiesAnnex1]

They are completely stock Vortec heads with comp cams 787-16 retainers (supposed to provide ample valve guide to retainer clearance) and LS6 beehive springs. Still has press in studs. Matter of fact, I should lay a straight edge across the top of them and make sure they didn't start to come out. I was told they'd be fine, but.. who knows. As I said above, I checked piston to valve clearance while the engine was on the stand, using lightweight checking springs and a dial indicator. Got each valve to max lift, zeroed the indicator and pressed the valve down until it hit the piston. I don't have the number on hand but I remember it being plenty. Yes, matching hardened oil pump driveshaft. What carb do you recommend for this setup?

Checking for bent pushrods is easy enough, as well as marks on the pistons.. would just need an inspection camera. Bent rods and valves on the other hand, not as easy I would guess. Would have to take them out, correct?

A question is whether you measured the clearance from the bottom of the retainers to the top of the valve guide with the oil seal on?

This is a place where you can’t assume that an assemblage of parts actually provides the necessary clearance regardless of advertising or “common knowledge“. There needs to be at minimum .050 inch between the bottom of the retainer and the top of the oil seal. This should be checked on each and every valve.

Another question is what was the damage to the original cam? Trying to see if there is a common thread.

Bogie

 

[BogiesAnnex1]

Often you have to mess around with high performance lifters of the fast recovery type to find where they like to run. Add to this they like to tick on high intensity lobe cams as the lobe on the back side comes off the peak lift fast enough to let a gap form at low RPM and these fast leak down lifters don’t react quickly enough to keep things at zero lash, quiet is not a design goal, fast recover from or prevention of chasing over rev gaps in the valve train is the design goal and often some ticking of the valve train is the result.

These type lifters like to be run with the plunger pretty deep in the lifter. The school of thought with these includes consideration that there is air entrained with the lube oil such that a large amount of oil in the adjusting chamber under the plunger allows the plunger to sink a bit thus reducing duration and lift at the valve. The extreme setting is to run the plunger right down or very nearly so to where it is about if not seated on the bottom limit of its travel. This will get into needing to fudge around with push rod lengths and of course longer push rod can have more buckle under loads with drives a sturdier and usually heavier push rod or some lightweight exotic and expensive material. But short of exotic NASA materials you’re now into sturdier components in the valve train, so you just get into this chain of events where you're throwing money into a bottomless pit.

For myself on the street I prefer to run a pretty much stock type lifter where I run the plunger just slightly off the retainer. Here the retainer needs to be a Circlip installed sharp edge up and not the stock bent wire bail as you have to insure that internal pressure will not blow the plunger out if you float the valve train. Here there essentially is no pump up as there is nowhere for the plunger to go up. This does allow a lot of oil in the lash chamber under the plunger so I have to accept that some reduction in duration and lift is possible as entrained air with the oil is compressed. The trade is a quieter valve train and no pump up recovery time as pump up can’t happen.

My standard for all builds is to set to go around the firing order adjusting intake and exhaust on each cylinder, helps to have a damper with 90 degree marks inscribed. This using the usual feel the push rod method just to get the engine started. Once running on the cam break-in cycle and the engine is up to temp then I go around and set the running preload to what ever I want that to be. Where the plunger is being sunk deep in its bore this can be a slow process as time has to be given even for fast leak-down lifters to settle into the preload your cranking in to them.

Hydraulics are not really setting a lash like a solid lifter, what’s going on is the plunger has a range of travel. At any reasonable point in the range of travel when the plunger encounters an opposing force which in this case is the valve spring it simply stops moving upward and will hold that position indefinitely unless a gap appears in the valve train. When a gap occurs in the valve train, you can use overreving the valve spring to where it looses control of the valve such that a gap or lash opens up then the plunger moves to return itself to a position against the spring load. When this happens the valve train is now adjusted too long where valves are not able to close so the engine falls on its face till the affected lifter’s plunger can return to its initial setting. So the time for this is controlled by that lifter‘s oil leakage rate from the bottom adjusting chamber. For a high performance lifter this can happen nearly instantly for a stock lifter intended to keep the valve train quiet recovery from these over speed events isn't very fast because the designers aren’t taking fast over-rev recovery as a design requirement for mom’s Monte Carlo.

As for top end lube this varies widely by lifter in that racing lifters are designed with the expectation that the rockers are rollers and little oil is needed plus that valve spring cooling will be handled from a direct pressure oil application built into the rocker cover or a seperate spray bar. Most hydraulics use some form of a metering valve as part of the pushrod cup. Depending on what the valve train is for example ball and socket or roller trunnion and how the valve springs are oiled and whether this engine will see if not hold a lot of RPM (the valve springs generate a lot of heat in use by their continuous compression and release cycling, oil is there cooling medium) so I will modify lifter bleed oiling as I see necessary to the end use and the equipment under the valve cover.

Bogie

 

[BogiesAnnex1]

The first thing with poly-locks is the top of the rocker stud needs to be flat. Unless you’re using genuine ARP rocker studs it’s unlikely the top of the stud is machined flat and normal (90degrees) to length of the stud. So if your using another brand it’s likely you need to gently kiss this surface to remove the end distortion the thread rolling process does to the top end of the stud.

The preferred process for locking the poly-lock is to set the preload position with the Allen screw backed off so it’s out of the way of using the body to set the pre load. Once done setting that position the body of the poly- lock is backed off about 1/16 of a turn (like that’s so effing easy to see) then the Allen screw brought down to contact the top surface of the stud then held to prevent the Allen screw from turning independently the poly-lock body is torqued to spec.

If you installed the lifters dry most often using either the spin or rattle the push rod method to locate the initial point of no movement then apply the recommended additional turn to set the plunger in its travel. At this point when you first crank the engine the plunger will be depressed till its bottom rests on the internal ring plunger stop of the main body. This stop is to prevent crush damage to the check valve assembly riding on the bottom of the plunger. The ring stop keeps the plunger high enough that the valve will be unseated somewhere in its lift curve sufficiently that the engine will fire. Then as oil pressure builds to feed the lifter’s reservoir that will through the check valve feed the bottom chamber under the plunger till the plunger fills any distance between where it started from to the zero lash position you set. It may take a few engine revolutions for all of this to settle down to the preset zero point.

If you pumped up the lifters before installing them if you go too fast and I can’t specify how fast is too fast but the oil trapped under the plunger may need more time to bleed than is given so if you pass over this too quickly the adjustment might be off.

Another and ugly possibility is infant lobe and or lifter failure at the rubbing interface between them. But this is pretty uncommon with Jones’ parts but poopoo happens.

Bogie