[north]

I bought a 69 Firebird earlier this year (convertible with 1bbl engine and 2 speed auto on the tree-the opposite of a muscle car!).

Runs well but was leaking some oil from the headgasket above the accessory block. I had a few questions about what we found and would appreciate any insight from the OHC braintrust here...

First is the engine was rebuilt not long ago (in terms of miles anyhow). Very clean inside, followers look really nice and very clean in the head, however...

1... the oil leak is probably indicative of a slight warp to the head, it was leaking right where the main oil passage to the head is, headgasket looked good there and no obvious signs of scratches or damage to the head or block that could cause the leak. plan is to send head out and have it checked and cut if necessary. No indication of any leakage internally between coolant, lubrication and combustion chamber, compression was perfect all around.

2... a bit of wear pattern on two valve stems, the rest look perfect. Problem is probably related to the fact that two of the "lifters" (forget the name of the OHC hydraulic follower type device) (not the same positions as the worn stems) are missing what looks like an oil flow restrictor at the top opening of the "lifter". Logically those two missing restrictors are resulting in some degree of oil starvation to the other ten rockers. Got to love the attention to detain of the engine builder! Anyone have some spare restrictors or lifter assemblies for sale?

3... I noticed that four of the fourteen bolts that secure the cam housing-cover to the head are actually studs, every OHC I look at has these in different locations. Scouring the internet for factory pics is inconclusive as to which positions those four studs should go. Second esthetic issue is the oil fill tube, everyone says they should be engine blue but this one and the one on my Sprint look so much like they are factory black. I know earlier years were painted for sure, is it possible that in 69 they were black, as part of other money saving paint changes that year?

[Jeff Hamlin]

Head Gasket failure in the area described is somewhat common.
IIRC BEST Gaskets offers a composite gasket that works well in this situation.

OE adjusters had the restrictor pin, however, there are aftermarket adjusters that do not as they are internally regulated. If you can determine if they are newer they should be OK.

The studs for the Cam Housing go in at all four corners. The front two hold the upper rear belt cover and the rear two are for fuel/vac line clamps.

I've never seen an OE factory fill tube anything but metallic blue.

Cheers.

[694.1]

It has always seemed a shame to pair this Six with the ST300. They drive SO much better with the TH350.
Probably turd gears too?

[north]

Thanks a bunch Jeff, I will order that brand gasket for it.

Any idea where I’d find a few or a set of hydraulic adjusters (just for restrictors)? They all look identical and when you push down on the two without the restrictors the dump a ton of oil out the hole, obviously not right.

Funny that the shop manual lists a special pn for a 12 position tray for the parts washer just for those hydraulic adjusters, to avoid exactly what happened here..

I drove the car a few miles when I bought it. Surprisingly zippy around town (didn’t get on a highway or hill though) compared to say my 350 2bbl lemans . The reason for this is that this engine trans combo came with 3.23 gears versus 2.56 on the 350-265 cars. I suspect the story will be different at highway speeds where my LeMans has plenty of effortless torque(not in muscle car terms).

As for why someone ordered a powerglide instead of a TH350 it wasn’t likely because of price. The TH350 was only $20 more than the 2 speed. But remember that the TH350 was brand new in 69 and anyone who’d bought new cars in the 50’s through mid sixties (and again in the 80’s!) had learned the hard way to never trust any new automatic transmissions until they were debugged over a few years. Ironically the TH350 was a great tranny from day one, but no one knew that in the fall of 68.

[66sprint]

North

Do you have a picture of the two adjusters that do not have the pins?

It is possible the pins are missing, rather than them being a different style of adjuster.

[63 bomb]

I've still got a few original restrictors laying around if you need them.

[einstein]

The "lifters" are called "lash adjusters". The "rockers" are "cam followers". I may have a new set of each I can spare. PM me your number and I'll give you a call.

Remember too there is an oil restriction device in the cylinder head feeding the cam system. Make sure it's there.

That ST-300 transmission is unrelated to the Chevy Powerglide. Earlier Buicks and Oldsmobiles, maybe 64, 65 A-bodies, I believe they had a switch-pitch torque converter. My ex's first car was a 64 Cutlass with a 330 V8. Actually felt pretty powerful due to the transmission. Some GMC Motorhome enthusiasts have used a 66 Toronado TH425 version of the switch-pitch for better in-town drivability.

The 69 THM350 was different than 70 and later, but I don't recall what, maybe something about the TV cable. My only base OHC6/TH350 was parted 25 years ago. I had installed a 69 Sprint engine, first with a borrowed ported 66 Sprint head that made it quick enough to get me in trouble, probably close to 12:1 CR. Later went to the 69 Sprint head, less power but still fun.

[north]

Didn't realize the extent of differences between powerglides and the ST-300, I just assumed it was a BOP bolt patterned powerglide. I noticed on pulling the engine that the torque converter looks like a rebuilt unit.

[north]

First pic shows the lash adjusters including the ones missing the restrictors. Second pic is the valve stem with some wear pattern.

The pictures with the adjusters out are too blurry but they all look identical in terms of detail and age, I doubt some are differently sourced than others.

I recall seeing that main restrictor in the head when rebuilding my Sprint but don’t remember where it was situated.

[north]

pm sent by the way

[einstein]

Originally Posted by north

First pic shows the lash adjusters including the ones missing the restrictors. Second pic is the valve stem with some wear pattern.

The pictures with the adjusters out are too blurry but they all look identical in terms of detail and age, I doubt some are differently sourced than others.

I recall seeing that main restrictor in the head when rebuilding my Sprint but don’t remember where it was situated.

It's in your first photo, dead center, that raised portion on the vale spring side of the head, between cylinder #2 and #3, and on the block mating side, there is a recess that's nearly oval with the hole at one end.

The restrictor if I recall correctly is thin steel tubing about 2-5/16" long, a deep crimp in the center making the internal passage almost a venturi, and a hole drilled in the side of the crimp. I think (memory here, caution!) that the hole was .080" I don't recall the diameter of the "venturi" passage, maybe 3/16"? I believe the side hole bled oil to the lifter galley, while the upper land that mates with the cam cover feeds the cam, which then has holes to dribble onto the followers. The hole and portal size had to do with metering the desired amount of oil to both systems.

I have a loose one around here somewhere, but probably won't find it in the near future.

PS left you a phone message.

[Jeff Hamlin]

I don't think you have to worry about the Metering Tube. That was an early production issue and PMD had it sorted out in '68-'69.



The Valve tip looks almost like it was "Tipped" more than worn.
But hard to tell from a pic.

I agree the Adjusters are likely OE but you would think OIL issues would have shown up sooner. Check the collar rings for ID numbers, some of the aftermarkets were tagged there.

[north]

I just checked, the main restrictor is present. Thanks all for the info, very helpful. If anyone has a few or full Las jh adjusters to sell please let me know.

[Jeff Hamlin]

North,
I have a 1967 Head/Cam from a parts engine I broke down a few years ago.
If you're interested I would sell just the Adjusters.
These are all OE and from a nice low-mile engine and have kept everything in place.

[north]

Assuming that 67 and 69 adjusters are the same I’d definitely be interested. I’ll pm you.

[Jeff Hamlin]

They are, PM sent. Thanks.

[north]

Originally Posted by Jeff Hamlin

North,
I have a 1967 Head/Cam from a parts engine I broke down a few years ago.
If you're interested I would sell just the Adjusters.
These are all OE and from a nice low-mile engine and have kept everything in place.

Jeff,

Looking at those pictures I see you have some kind of spring steel keepers on the followers, neither of my engines has them and no sign of it in the shop manual, was that something that was dropped on later years?

[63 bomb]

My parts book lists the clips as 66-67 only and part number 9784513. $0.33 each in 1975 LOL!

[camerjeff]

The cam follower retainers were only used on the 230 CI engines in 66 & 67, they only served a purpose to keep the followers in place when the cam cover was being lowered onto the head. They also caused issues when they sometimes broke and the pieces got jammed in the valve train, so you don't need them on any year engine. I stopped putting them back on any engines after getting s couple of used engine cores and finding they had flat lobes and those lobes had broken retaining clips.
I don't know what came 1st the flat lobe or the broken clips, but I just figured I would eliminate 1 possible issue.

[north]

Thanks, I figured it was something like that.