[mgarblik]

Lots of good points made in this thread so far. 51 year old engine in pretty good condition vs opening it up and installing new parts of unknown quality likely made in China. That's the tough decision. A 74 350 2 bbl. engine is a low stress engine and is likely to run in a worn condition for a long time. Because timing chains are a "thing" with Pontiac engines, I would make sure it's not all stretched out. Take some spare high failure parts with you and a few tools and go have a fun time. JMO. Taking a second car is really not much different than trailering the Ventura.

[Holeshot71]

The way I see it is you’re not gonna gain any power going to a 4-barrel without a cam change. So I’d leave it alone and enjoy the ride. If you decide to put the 4-barrel on it do it along with a cam, lifters timing chain and valve springs minimum..And while your at it, rings bearings seals and gaskets..lol

[John Milner]

If the engine is running good, I would be tempted to check/replace the timing chain if original and drive it as is. If it breaks, then go through everything.

[Shiny]

If you decide to replace the timing chain, consider having a spare timing cover handy. Stuff happens to 50-yr-old metal exposed to coolant.

A lesson I keep learning:

[Elarson]

I'll cast my vote for leaving it alone. The 50 year old parts are worn in and happy together. Disturbing that sets you up for a full rebuild.

Eric

[b-man]

If it ain’t broke don’t fix it.

Just don’t drive it like you stole it and it’ll be fine.

Save your funds, time and energy for the future 400 or 455 that will replace it.

[Verdoro 68]

The inspection has begun. Honestly not as bad as I was expecting. Unless I'm missing something, it just looks like a high milage engine. Lots of gunk around the valves likely due to bad valve stem seals and worn guides. Timing chain has a bunch of slop, so that's going to get changed.

[b-man]

Actually looks very clean inside the valley, previous owners didn’t neglect to keep the oil changed.

Worn out timing chain as one would expect. Regular maintenance item. Maybe a new water pump while you’re in there, keep the old one in the trunk.

You’re pretty good at his type of thing, maybe too good for your own good.

[Sirrotica]

If you're not planning on removing the pan and cleaning it out, DON'T try to dig out any of the hard sludge in the heads or valley, leave it alone undisturbed. If you can't remove a part from the engine and clean it thoroughly leave it alone. The best way to clean up an older engine is to change oil and filter and let the stuff dissolve slowly being removed from oil and filter changes.

I'll speak from too many failed attempts to clean up a dirty engine, you'll do more harm than good. Especially if your plan is to drive it to Tucson. All that loose hard carbon will end up in the oil pump screen, clog it, starving the bearings, game over. All the flushing and attempts to corral that hard black carbon usually fail 9 out of 10 times, poor odds for anyone that gambles.

[Formulas]

It does look pretty good for an aged assy, ... The buildup on the back of the valves usually is alot worse

[dataway]

Yep, I think it looks great for it's age, that valley is pristine.

I've seen them with the rockers living in a solid tunnel of sludge....and still running.

[steve25]

The worst thing you can do to a motor with over 50,000 miles of mineral based oil having been run thru it is to use a product like Rislone or something else like adding a qt of ATF or any other type of motor flush.

While these things might free up stuck lifters due to varnish build up an all too high percentage of the time as stated in post # 29 you will clog off the oil pump pick up screen and the motor will slowly suffer from reduced oil flow volume .

This condition is far worse then a ticking lifter , BTDT twice!

[Verdoro 68]

This car is funny. It was very well worn, but it seems to have always been mechanically maintained. Almost all of the replacement parts I've found have been AC Delco.

We've haven't ever put any cleaning additives in it. Cole might have put some Lucas in it when the lifter was ticking, though. It was running quietly and the lifter tick was gone before we took it apart. Whatever crud you see in the pictures could have fallen in when we took off the valley pan. The heads look like the valley. None of the lifters appear to have stand out excessive play or sponginess so I'm going to leave the valve train well enough alone.

I am debating if I do anything about the low compression on 5 and 7 since we've got it down this far. Maybe it's coincidence, but those are the cruddiest looking intake valves. For a while, I planned to pull the head and put a new gasket on since both cylinders are down. However, compression went up after he drove it for a while, so now I'm thinking it's the rings. If that's true, not much I can do about that without a rebuild. Maybe I look the other way as to not make anything worse.

[steve25]

Add a V8 size can of a product called restore.
I will likely boost the compression a bit in those low cylinders .

And yes add it even if your full on oil now, no need to drain any out.
They offer 4,6 and 8 cylinder motor size cans.

Be sure to shake the can well!

[Formulas]

Low compression combined with extra crud on the same cylinders intake valves would indicate worn guides or valve seals gone south on those cylinders, If it was my gig i would put valve seals in it, Not that hard to do at this point in time and may help a lot plus i am sure they are hard / possibly cracked anyways ... If you have a compression tester with a shrader valve in the end you take the shrader valve out use the hose to put compressed air in your low cylinders and see if the intake valves are leaking at the seats, bonus that the intake is off for the visual

[Verdoro 68]

I did the valve stem seals right after we got the car. They were cooked or complete gone in some cases. It helped with oil consumption quite a bit. When I did the seals in those two cylinders I used compressed air to hold the valves. They had a hard time wanting to stay up. I’ll do it again now that I have the intake off and can see the valves.

[Verdoro 68]

The front seal has been leaking pretty good for a long time. Good call on the timing chain. It's way worse than I thought. Wondering if the yellow markings on the gasket indicate it's a factory gasket? Balancer looks ok. No obvious signs of the rubber failing, but I have a new one off the GTO I'll probably swap in.

[SD455DJ]

FWIW, the ’74 350 2-bbl and 4-bbl (and GTO) engines ran the same lo-po cam found in the ’68 –’73 350’s (except 350HO’s) and 2-bbl 400’s. It’s the 9777254 cam with 269/277/113 @ 0.377”/0.413” lift. If’n it was me, I’d convert to a 4-bbl intake and Q-jet as well. You already have dual exhaust and 2.73’s, the same as a Ventura with auto and AC with the 350 4-bbl. The factory rated the 4-bbl 350 30hp more than the 2-bbl version (200 hp vs. 170 hp with dual exhaust), so that is a power increase you can feel and measure.

Dennis

[Verdoro 68]

Originally Posted by SD455DJ

FWIW, the ’74 350 2-bbl and 4-bbl (and GTO) engines ran the same lo-po cam found in the ’68 –’73 350’s (except 350HO’s) and 2-bbl 400’s. It’s the 9777254 cam with 269/277/113 @ 0.377”/0.413” lift. If’n it was me, I’d convert to a 4-bbl intake and Q-jet as well. You already have dual exhaust and 2.73’s, the same as a Ventura with auto and AC with the 350 4-bbl. The factory rated the 4-bbl 350 30hp more than the 2-bbl version (200 hp vs. 170 hp with dual exhaust), so that is a power increase you can feel and measure.

Dennis

Already on it It's getting a '68 manifold, '68 Q-Jet and valley pan. I do have a set of 1.65 rockers I considered as a band aid for more lift, but then I remembered that I'd have to clearance the heads.

[SD455DJ]

Ha! I should have known you'd already be doing that! Excellent! It'll still run decent without the 1.65's.

Dennis