[Rich-Tripower]

Okay, since my last report I've been through the ringer on this car. Found out I had fuel but no spark. Then found that the fuel pump took a dump and was leaking like mad. Got a new fuel pump. Found that the capacitor in the point set was bad, fixed that. Should have spark AND fuel. No fuel. Turns out the new fuel pump had the IN/OUT outlets in opposite positions from the original. Pulled the fuel pump out, fixed the plumbing arrangement. Should be good to do, but no, stripped the threads in one of the fuel pump mounting bolt holes. Helicoil to the rescue. Then the tang on the helicoil wouldn't break off properly. Anyway, conquered that. Then, no fuel again. Figured the new pump pooped the bed again. Nope, found out the diaphragm rod had come loose from the lever. Fixed that. Have fuel again. Then the center carb took a dump, fuel everywhere. Rebuilt the carb entirely (again). Now, fuel and spark. Finally. Should be good to go.

Cranks okay, kicks a bit but won't catch. Try more advance, better. Try more or less choke. Not much progress. Want to double check the spark plug wires, all good, routed correctly. While cranking, I see a bit of blow by out the carb. Huh? Do I have the distributor out of sync? It seems to catch on a few cylinders but not enough to run. Distributor settings are good, timing is good, wiring is good and proper.

So, I figure it is time to get to real TDC and check the distributor is in right. I tell my cousin to put his finger on the spark plug hole of #1 and let me know when it pushes his finger off. It didn't move his finger at all. Oh sh*t, do we have one or more bad cylinders? I decide to back off the rocker nuts at least a little way to make sure the valves are closing, now cranking blows my finger off the hole with a vengence, scared me to pushed so hard. Well, that's good news.

So. We can't get it running because the valves are hanging open. Let's run down where I'm at with setting the valves. Springs, valves, pushrods, rockers, rocker nuts, rocker studs and rocker balls are all stock originals. I was told to just torque down the nuts and it should be good to go. But, when torqued down it is holding most of the valves open at least a bit.

Could I have gotten the wrong lifters when I built the engine? Does the 389 use specific lifters? I seem to recall the block was decked a few thousandths when it was machined, could that be enough of a difference to cause this problem? How would I compensate for that?

What solutions are available without converting to a Chevy style valve lash set up with new studs and lock nuts? Can I simply get some Chevy lock nuts and lash the valves while using the original Pontiac studs or will they bottom out on the stud shoulders before reaching the proper lash? We want to retain the stock valve covers so aftermarket poly locks aren't really an option, at least not using the tall poly locks with which I am familiar.

I am confident this PITA will finally run when we can get the valve train functioning properly. It is trying real hard to run, but open valves just won't let it.

[bill ryder]

Who rebuilt the engine? Could the cam have been installed out of time?? Very first thing I thought of after reading about no compression on finger test! "Bill"!

[Rich-Tripower]

Originally Posted by bill ryder

Who rebuilt the engine? Could the cam have been installed out of time?? Very first thing I thought of after reading about no compression on finger test! "Bill"!

The compression came back when I backed the rocker nuts off a few turns. The valves were still opening and closing, just closing all the way.

I rebuilt the engine. I'm certain the timing chain set was installed properly. Besides, if the timing chain set was off by much it'd have been banging valves into pistons wouldn't it? If it isn't a rocker arm setting issue, I guess the only thing left will be to check the cam timing. Is there perhaps a way to check that before tearing the front of the engine off?

[rexus31]

Post pics of your rockers and rocker nuts. Without seeing what you are seeing, we are throwing darts in the dark.

[bill ryder]

Take your plugs out, remove the dist cap and use a wrench to rotate the engine. When the balancer timing mark gets close, watch your cam lobes and rotor position. You will know if it looks close or not. I'm just old school, but things haven't changed with these old engines.

[Rich-Tripower]

Originally Posted by rexus31

Post pics of your rockers and rocker nuts. Without seeing what you are seeing, we are throwing darts in the dark.

As I've said, everything in the heads is bone stock original. The lifters are new of course. The cam is new of course. The cam is actually the 360hp grind since the 348hp grind hasn't been available for quite some time. As you can see, the stock nuts, rockers and shouldered studs are all in place.

Originally Posted by bill ryder

Take your plugs out, remove the dist cap and use a wrench to rotate the engine. When the balancer timing mark gets close, watch your cam lobes and rotor position. You will know if it looks close or not. I'm just old school, but things haven't changed with these old engines.

I've done it a couple of times already, but I'll do it again tomorrow to double check my double checking. Rotor position is dead on where it should be according to the shop manual (pointing to the base of the vacuum can when on #1 TDC compression), I know this because I've had the distributor out numerous times to check various things such as the points, points gap, etc. I always set it to TDC before pulling the distributor. Tomorrow I will closely scrutinize the rocker movements as it approaches TDC on compression stroke on #1. If the timing set were off just a tooth, it would still look pretty close I suppose so this will only tell me if it is wildly out of sync but worth the effort before I tear into it further. But unfortunately it is all making more sense that the timing set is off index. Poop.

[rexus31]

I could be mistaken, but don't the stock nuts just torque to spec? It's possible your pushrods are too long.

[Rich-Tripower]

Yes, the nuts torque to spec. The pushrods are the originals. Unless the 360hp cam has a larger base circle than the 348hp cam I can't see how the pushrods could be the issue.

[Baron Von Zeppelin]

At this point it won't hurt to re-verify as much as possible.
i think you are right about the cam synch being fine, but run the ritual any way.

The longer pushrods go with heads that have screw-in studs.
The earlier engines (like 389) used a shorter pushrod.
Measure what you have any way i guess.

All the Pontiac standard hydraulic lifters are the same throughout all the GTO years.
(except Ram 4 & 5)
But someone might have shipped you Chevy or Olds lifters by mistake, as another possibility.

Very sorry its been giving you some fits, but very similar things happen to lots of others too.

[Baron Von Zeppelin]

Something else just thought about -
if you are using a 1/2" torque wrench to do the 20 lbs- they are not very accurate at low settings. Use a 3/8" or 1/4" torque wrench.
Or just wing it with a 3/8 ratchet

[b-man]

You will need either small block Chevy self-locking nuts or poly locks and the valves will need to be adjusted the same way as a Chevy that has an adjustable valvetrain.

Why?

Because once you rebuild the engine all of the machining operations add up and create the condition you have experienced.

Milling the heads for cleanup reduces the distance between the rockers and the cam. Doing a valve job sinks the valves into the heads, to compensate the rockers need to sit higher on the rocker studs.

Simply torquing the factory rocker nuts down onto the tapered shoulder on the stock bottle neck rocker studs won't work anymore. It only works on fresh factory engines in almost all cases.

There is only about .060" of downward travel in the lifter plungers left after the factory 'adjustment' is made, all easily used up after the rebuilding process is completed. This is what is holding your valves open.

The 360 HP cam (9779068) has the same base circle as the 524009 325 & 348 HP cam (same as the 9779067) so that is not your issue.

Get a set of the correct adjusting nuts and get the valves adjusted, if you need additional clearance for the short poly-lock nuts thicker valve cover gaskets are readily available.

I found this to be true when rebuilding a 1964 325 HP 389 GTO engine that I acquired many years back using an 068 cam, the stock rocker nuts absolutely won't work.

[Rich-Tripower]

Originally Posted by b-man

You will need either small block Chevy self-locking nuts or poly locks and the valves will need to be adjusted the same way as a Chevy that has an adjustable valvetrain.

Why?

Because once you rebuild the engine all of the machining operations add up and create the condition you have experienced.

Milling the heads for cleanup reduces the distance between the rockers and the cam. Doing a valve job sinks the valves into the heads, to compensate the rockers need to sit higher on the rocker studs.

Simply torquing the factory rocker nuts down onto the tapered shoulder on the stock bottle neck rocker studs won't work anymore. It only works on fresh factory engines in almost all cases.

There is only about .060" of downward travel in the lifter plungers left after the factory 'adjustment' is made, all easily used up after the rebuilding process is completed. This is what is holding your valves open.

The 360 HP cam (9779068) has the same base circle as the 524009 325 & 348 HP cam (same as the 9779067) so that is not your issue.

Get a set of the correct adjusting nuts and get the valves adjusted, if you need additional clearance for the short poly-lock nuts thicker valve cover gaskets are readily available.

I found this to be true when rebuilding a 1964 325 HP 389 GTO engine that I acquired many years back using an 068 cam, the stock rocker nuts absolutely won't work.

I really did want to hear something like this, especially the part in bold. I have to be realistic in that the cam timing could be a culprit but I want to check out other things first before tearing the front of the engine off. Trying Chevy style lock nuts will certainly tell me if I'm on or off target and if what you say is accurate, that is not a bad course of action.

I do know that the block was decked because the block had two frost heave cracks when we started. I had it repaired by an expert in the field and he said decking it was required when done. I just don't recall how much. I honestly don't recall if the heads were surfaced but they might have been. I don't recall if the head gaskets are the same thickness as the originals. My point is, without trying too hard I just may have used up that remaining .060 of lifter travel you mentioned. It sure would explain our experiences recently.

I hope I can pick up some Chevy lock nuts locally. I have some old ones from my Chevy projects (I put poly locks on my Chevy engines) but I'm not throwing used parts into the mix at this point to save a tiny amount of time and expense.

[Rich-Tripower]

Found Chevy lock nuts locally, will run the valves again tonight with lock nuts and check a few other things and see where we stand.