[FlyJS41]

Originally Posted by chiphead

If you think a lifter is bad, go ahead and change the cam. No sense doing it twice.

I've definitely considered this, but it seems Pontiac cam swaps are a PITA. I'd need someone to help or have to pay somebody to do it.

[MarkS57]

Originally Posted by FlyJS41

I've definitely considered this, but it seems Pontiac cam swaps are a PITA. I'd need someone to help or have to pay somebody to do it.

I've haven't found them to be that difficult, especially in a 68. Doesn't even have a pressed on balancer like some other 350's. If the car has AC then it is more challenging with the AC condenser in the way. Sometimes, a wrecked cam lobe is easy to see just looking at.

My 68 350 was also no slouch. 2 bbl 2 speed to start. Rebuilt with just a re-ring on stock pistons. Clevites, 60 lb oil pump, 067 cam, 68 4bbl manifold & qjet, nothing special for ignition & stock duals. I did swap the heads for 16's along with a TH400. With 2.56's out back, it would easily break the tires lose and with those 2.56's, a nasty highway car. Miss that car sometimes.

[FlyJS41]

Originally Posted by MarkS57

I've haven't found them to be that difficult, especially in a 68. Doesn't even have a pressed on balancer like some other 350's. If the car has AC then it is more challenging with the AC condenser in the way. Sometimes, a wrecked cam lobe is easy to see just looking at.

My 68 350 was also no slouch. 2 bbl 2 speed to start. Rebuilt with just a re-ring on stock pistons. Clevites, 60 lb oil pump, 067 cam, 68 4bbl manifold & qjet, nothing special for ignition & stock duals. I did swap the heads for 16's along with a TH400. With 2.56's out back, it would easily break the tires lose and with those 2.56's, a nasty highway car. Miss that car sometimes.

Non-AC car, so I’ve got that going for me. What little I’ve seen about changing cams in a Pontiac suggests pulling the motor. I’ll do a little more research, but I’m definitely not set up to pull a motor at my place.

[tom s]

pretty sure the 68s have enough room to pull the cam out after you get everything out of the way.I would just make sure there is no flat lobes or ground lifters before you do anything.If there is ground metal in the engine it will likely need a good cleaning and rebuildTom

[Sirrotica]

You can change cams in that car without pulling the engine, been there done that.

If the cam lobes are MIA there is another member here that had a fresh engine that wiped a cam lobe that flushed as much as of the residue out of the engine as he could without removing it. Then as per my suggestion, he installed a by pass oil filter to remove any of the microscopic metal from the oil system so it wouldn't continue to circulate. He also attached a large permanent speaker magnet to the bottom of the oil pan to further trap any errant ferrous metal from re-circulating. It seems to have done the job without disassembling the engine. He was tapped out for funds, and couldn't afford to re-do the engine another time, so I suggested this alternative of ridding the engine of all the ground up metal

FWIW, there are probably 100s of thousands of SBCs that have eaten camshafts that just got new cam, and lifters, an oil change, and sent down the road, never to have any further engine problems for the life of the car. The by pass filter will remove any foreign matter from the oil first pass down to 5 microns, much more efficient than the factory filter is at removing the small stuff first pass. The powerful speaker magnet should help also.

[pontiacmark]

I had a very similar car-68 Lemans convertible. Replaced 2-bbl with Edelbrock performer and Holley 600. Engine otherwise bone stock. The ST300 was replaced with a TH400. With 2.78 single track it ran mid 10s 1/8th mile. With a change to 3.08 posi it ran 10.20s (~high 15s 1/4). . Mine was heavy A/C car but would easily roast the tires. I would say you could do a cam swap in car but you would probably need to pull radiator.

[FlyJS41]

Originally Posted by Sirrotica

You can change cams in that car without pulling the engine, been there done that.

If the cam lobes are MIA there is another member here that had a fresh engine that wiped a cam lobe that flushed as much as of the residue out of the engine as he could without removing it. Then as per my suggestion, he installed a by pass oil filter to remove any of the microscopic metal from the oil system so it wouldn't continue to circulate. He also attached a large permanent speaker magnet to the bottom of the oil pan to further trap any errant ferrous metal from re-circulating. It seems to have done the job without disassembling the engine. He was tapped out for funds, and couldn't afford to re-do the engine another time, so I suggested this alternative of ridding the engine of all the ground up metal

FWIW, there are probably 100s of thousands of SBCs that have eaten camshafts that just got new cam, and lifters, an oil change, and sent down the road, never to have any further engine problems for the life of the car. The by pass filter will remove any foreign matter from the oil first pass down to 5 microns, much more efficient than the factory filter is at removing the small stuff first pass. The powerful speaker magnet should help also.

I gotta say, the speaker idea is pretty ingenious.

[1968GTO421]

Good advice from Brad. You could easily check for wiped out lobes by changing oil and filter. In particular use a filter cutter to cut open the filter to examine the element for "glitter" from the cam lobe if it's wiped. I got my cutter from Summit (not far from you). Lots of excellent advice here from members. Best of luck to you.:

[FlyJS41]

Thanks for all the input, fellas!

Something else for me to consider is the following from our club mechanic. He’s retired, so this is not a job he’d take on. He provided the advice as information only, not for financial gain.

“ok.
three gear heads say basically the same thing.
From your compression test.

with the two cylinders being the same ones not pumping oil thru the push rods having the lower compression readings, replacing the hydraulic lifters will not solve the problem.

The cam bearings are failing.
The engine will again have to be opened up and the cam replaced.”

I’m thinking it might be a good idea to just pull the motor and send it to a competent machine shop for inspection.

[1968GTO421]

Originally Posted by FlyJS41

Thanks for all the input, fellas!

Something else for me to consider is the following from our club mechanic. He’s retired, so this is not a job he’d take on. He provided the advice as information only, not for financial gain.

“ok.
three gear heads say basically the same thing.
From your compression test.

with the two cylinders being the same ones not pumping oil thru the push rods having the lower compression readings, replacing the hydraulic lifters will not solve the problem.

The cam bearings are failing.
The engine will again have to be opened up and the cam replaced.”

I’m thinking it might be a good idea to just pull the motor and send it to a competent machine shop for inspection.

Sounds like the best plan. Members here can refer you to competent machinists in the Atlanta metro area. Should be many there, some who are actually familiar with Pontiac engines.

[MarkS57]

Originally Posted by FlyJS41

snip the old-timer building the engine said those cams were "good for nothing but noise" snip.

There is some truth to the noise. While my 703 is quiet at idle and performs very well generally, the noise gets a little annoying at cruise over a fairly short period of time.

[NeighborsComplaint]

Cam timing is retarded. That's how they run when they are way off.. Vacuum is good but no bottom end power at all and they wake up (relatively speaking) around 2,500 rpm but never really run right. I'll bet if you pull the timing cover you'll see it's off a tooth or more. Line up the dots and it will run like a different car.

The first cam change I did as a kid was on a Ford 390 4 speed in a Galaxie. I cheaped out and reused the worn out old timing chain and mis-aligned the dots. The car could barely pull away from a stop sign without riding the clutch. When it hit around 2500 rpm it was like you turned a switch and the power would finally come on. I pulled it apart and found my mistake. Difference was like night and day once I got the cam timing correct.

[FlyJS41]

Originally Posted by NeighborsComplaint

Cam timing is retarded. That's how they run when they are way off.. Vacuum is good but no bottom end power at all and they wake up (relatively speaking) around 2,500 rpm but never really run right. I'll bet if you pull the timing cover you'll see it's off a tooth or more. Line up the dots and it will run like a different car.

The first cam change I did as a kid was on a Ford 390 4 speed in a Galaxie. I cheaped out and reused the worn out old timing chain and mis-aligned the dots. The car could barely pull away from a stop sign without riding the clutch. When it hit around 2500 rpm it was like you turned a switch and the power would finally come on. I pulled it apart and found my mistake. Difference was like night and day once I got the cam timing correct.

I would not be surprised at this point, considering all the simple errors I've found in this build. It'll be a month or two, but I'm sure the disassembly report is going to be interesting.

[chiphead]

Why do you think the cam bearings are bad? Is oil pressure low? Oil feed for lifters comes up from main gallies drilled front-to-back on each side, not directly from cam bearings in a Pontiac. You can pull the cam in-car and see if the cam bearings are wasted before you pull the engine. If the cam bearings are still good, I'd do a in-car cam swap. Unless you're just wanting to go through the engine?

[FlyJS41]

Originally Posted by chiphead

Why do you think the cam bearings are bad? Is oil pressure low? Oil feed for lifters comes up from main gallies drilled front-to-back on each side, not directly from cam bearings in a Pontiac. You can pull the cam in-car and see if the cam bearings are wasted before you pull the engine. If the cam bearings are still good, I'd do a in-car cam swap. Unless you're just wanting to go through the engine?

Just going off the advice of my friend. Oil pressure is good according to the gauge. Compression is low in cylinders 6 and 8. Intake lifter/push rod in 6 has no oil coming through. Number 8 intake lifter/push rod has only a trickle.

[Will]

The cam bearings being bad makes no sense to me. If the lifters on those two cylinders are bad then you won't get proper oiling and the compression readings would be low, just like what you're seeing. The cam bearings have nothing to do with the lifters oiling.

If you pull a lifter, look at the bottom of it. If the bottom of the lifter is worn, then for sure the cam lobe is too. If the bottom of the lifter is okay it could just be cheap, crappy lifters that aren't functioning properly. You can also tell if there's excessive lobe wear by just looking at the lobes. Compare known good lobes with the suspect lobes. If the wear pattern is different, and covers more of the lobe on the suspect ones then they're going bad.

[FlyJS41]

Originally Posted by Will

The cam bearings being bad makes no sense to me. If the lifters on those two cylinders are bad then you won't get proper oiling and the compression readings would be low, just like what you're seeing. The cam bearings have nothing to do with the lifters oiling.

If you pull a lifter, look at the bottom of it. If the bottom of the lifter is worn, then for sure the cam lobe is too. If the bottom of the lifter is okay it could just be cheap, crappy lifters that aren't functioning properly. You can also tell if there's excessive lobe wear by just looking at the lobes. Compare known good lobes with the suspect lobes. If the wear pattern is different, and covers more of the lobe on the suspect ones then they're going bad.

Nothing is off the table, as I'm trying to learn as I go. Is my friend confusing these symptoms with another manufacturer's engine?

["QUICK-SILVER"]

Passengers side oil galley runs from front to back and only feeds lifters.
Drivers side oil galley runs from back to front and feeds lifters/crank/cam.
Oil crosses from one side to the other at the front main bearing.
Number 8 exhaust lifter is at the end of the line for oiling.

Was watching for oil done at starter speed or engine running?

Was #8 exhaust rocker getting oil?

Was #6 intake rocker dry, galled (turning blue), loose from wear?

What rockers and adjusting nuts are you using?

When watching for oil, did all rockers appear to have the same amount of travel/valve opening?

Clay

[FlyJS41]

Originally Posted by "QUICK-SILVER"

Was watching for oil done at starter speed or engine running?

Was #8 exhaust rocker getting oil?

Was #6 intake rocker dry, galled (turning blue), loose from wear?

What rockers and adjusting nuts are you using?

When watching for oil, did all rockers appear to have the same amount of travel/valve opening?

Clay

Oil volume was observed with engine running at operating temperature.

#8 exhaust has good flow.

#6 intake rocker ball was slightly galled/blued.

Initially, Comp Magnum 1.5 roller tips (PN 1451) with lock nuts. Then, as a test control, Scorpion Endurance 1.5 full rollers with pollylocks. (FWIW, the aluminum rockers transfer the engine harmonics "better" and the chirping of the lifters is easier to hear.) All push rods were checked for straightness and blown out to ensure no obstructions.

Near as I can tell, travel seemed consistent with both sets of rockers.

["QUICK-SILVER"]

These heads get converted from press-in studs to screw-in?

Curious about chirping noise. If it's pushrod rubbing guide plate.. It may be enough to keep the pushrod ball from seating good in the rocker cup. That would prevent oil from squirting out the oil hole in the rocker.

Clay