Open it up or leave it alone?
 

My son and I are planning on roadtripping his Ventura 1800 miles to the Duct Tape Drags in October. We spent the last year going through the chassis-related items - suspension, brakes, steering, as well as the cooling system. He's been using the car as his daily driver around town for the last 8 months with minimal issues.

One thing we haven't touched is the engine. It's the original '74 2bbl 350 with 46 screw in stud heads. It has a little over 100k according to the odometer. The engine appears to have never been opened up or out of the car. When we first got it, I ran a compression check and cylinders 5 and 7 were around 80psi. The others were at 120. Since he's been driving it, 5 and 7 now measure 100psi. I originally thought the lower compression might be due to the head gasket between the cylinders, but since it got better after driving maybe it's the rings? I did a coolant check and it came back negative for combustion material.

When we fired it up after sitting a few months while we worked on the chassis, it had a lifter tick, but it went away after it ran for a short while and we dismissed it. A couple weeks ago my son changed the oil and I had him put 6 quarts of Driven 15-50. Soon after it the lifter tick came back. The dipstick was reading high, so he drained some oil to put the level where it should be and the tick mostly went away. He pulled the rocker covers and everything looks good with no sign of a flat cam lobe checking out. I finally put an oil pressure gauge on it over the weekend, and to my surprise the pressure is great.

I'd like to avoid getting stuck in the desert on the way to Arizona. I'm thinking the best course at would be to minimally disturb things ahead of October, but I don't love the low compression, and I wonder if tick could come back to haunt us. I'm leaning towards installing the 4bbl, removing the valley pan to get a look at the lifters and cam and going from there. Thoughts?

Trust what ya got or, a opened up engine? A lot of what if`s come in on new engines.

I’d be most concerned with the condition of the timing chain.

Pop the distributor cap and watch the movement of the rotor while you turn the crank back and forth.

If the chain appears to have too much slop in it then consider replacing that. Otherwise leave well enough alone.

If you have AAA consider upgrading to their highest membership tier for towing, you’ll need to do it at least 30 days in advance of your road trip.

sounds like you have a good handle on it. Pull the valley pan and check it out. Of course, with that many miles there are lots of things that could go south on an 800 mile trip. Such as. a broken timing chain, oil pump failure, etc.. Anyway, if you really don't want to get stuck in the desert then take your daily driver, or, bring your tools, a few spare parts and keep your fingers crossed.

Feels like you are trading risk for unforeseen problems and delays in the engine work for risk of an engine failure on a long trip.

Not a simple question as you know!

I can tell you my 4bbl, cam, and lifter swap snowballed beyond reason (I don't even want to talk about it), but that's me and not you.

You do such nice work I don't see you settling for just swapping lifters. Mission creep beyond what you hope for can happen, so planning for the worst might help you prepare.

Maybe compare "what's the worst that can happen" for the two scenarios?

I personally have never done a leak-down test, but that might help you understand the source of the low compression pressure?

We have AAA, I'll double check on the plan. I hadn't considered following him in my daily driver. It's not quite as fun, but it's more practical - more room to store tools and parts and back up transportation in case something breaks.

I checked the timing chain for slop a while back when and didn't notice anything excessive. The fuel pump is another risky item. If we do the 4bbl swap, I'll change the pump. Might be a good idea to buy a backup for the trip.

I thought about a lifter swap, but that feels a little risky. I'd hate the wipe the cam. I do have a cheap leak down tester, but I couldn't get it working right. Maybe I'll give it another try.

I'm the cautious sort .. first, don't risk anything that could leave you in a life threatening situation in a desert.

I like the chase car idea, but yes, not as fun. AND when you get back home and the Ventura ran perfect the whole time you'll be pissed that you took a chase car. But if you DON'T bring a chase car then something will go wrong :)

I'd second checking the timing chain, assuming it's already been changed once if it's got that kind of miles on it, if it's never been changed then it's amazing it hasn't let go yet.

Spare points, condenser, coil, fuel pump. OEM lifters have to be on their last legs, but from what I have seen and badly worn original lifter won't prevent the car from being driveable, just makes it noisy and down on power.

Not sure what your situation is, or what plans you have for the Ventura at the event ... but there is always the option to trailer the car, you get to be in the same vehicle for the drive, no worries about the Ventura breaking down.

You need to check the condition of that timing chain and doing such can be done in less then 30 minutes without pulling the timing cover off.

It's likely the timing chain has been changed over the years. If it has, it's been a while. I'll check the slop again now that the hood is off. If I pull the intake and valley pan, it's not that much more to do the timing cover. It needs a new seal anyway. Slippery slope...

Thinking more about swapping in a fresh set of lifters to get rid of the tick. What's the level of risk of putting a new set of Johnson lifters on a 50 year old OEM cam?

I carry those items mentioned and spare water pump,belts,hoses,parts to repair alternator,and my qjet spare parts.When I took my street driven TA to Norwalk took extra driveshaft. I even took spare distributor, push rods,rockers,nuts few gaskets for intake. My friends would laugh in a kind way what I took. Always be prepared.Show on Saturday, race on Sunday.

I would pull that noisy lifter out and take it apart to, 1) see how much play the push rod plunger might have in the body and if varnish might be restricting the movement of the plunger, and 2) see if there’s any crap in it .

Surely by now the original cam has at least one or two lobes going flat.

Waste of time putting new lifters on a worn out original cam.

Leave it alone. Rent a U-Haul car trailer to pull it through the desert. Enjoy it at the destination-drags. Tow it home.

As practical as that is, he really wants to drive has car on a road trip. He's been talking about it since we bought the car. We're also limited on tow vehicles. Following in my daily would probably be the best option.

You're probably right. I was more concerned about a new lifter wiping a lobe and taking the whole engine out, but I'm sure the cam is on it's last legs. I also don't really want to drop a new cam in a 100k mile engine unless I'm going to go through the whole thing.

This is probably the most practical place to start in terms of the valve train - take it apart, inspect and clean the lifters, and put it back exactly as it was.

I am making plans to attend that event, but it is much closer to me.

Me? I'd throw in a mild cam/lifter/timing chain set (Summit 2800 for the win?), stick on the 4bbl, and go nuts. Pack snacks, drinks, and a fire extinguisher.

I would also want the experience without the trailer or chase car, but definitely get the previously mentioned insurance.

You probably haven't had the chance to do something so reckless and ill-advised since you were in college. Your son will learn about managed risk. And both of you will have perma-smiles for several months/years!

Ok, this is what I really want to do, but have been talking myself out of it due to the high mileage and low compression. I think I even have the 2800 in my Summit cart.

It looks like we'll be caravanning with a few of his friends who are trailering a car, so that adds a little bit more of a safety net.

When it comes to cam/lifters with that kind of miles, usually several of the lifters have a considerable dish to them, with the associated lobs worn to match. Yep, it's all or nothing when it comes to replacing those parts at that mileage.

Perhaps bring a "tow bar"? I don't know much about them, but maybe it could be a backup to get the car where it needs to be fixed if necessary.

If needed you can usually rent a u-haul and a tow dolly for the trip home if something breaks down permanently. Have fun!

Do what you posted back in number 14, but the very very first thing to do is to yank the plugs out , kill the power to the ING system then remove both valve covers and crank motor over looking for each push rod to be spinning like they should once you put a mark on them to make viewing easy.


While doing this you need to note if there are any that are spinning slower then the others, because they are going south and would be reason enough for me to replace the cam and lifters now.

Cam and lifters waring a that fine grit getting into the oil supply speed up engine ware.

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.

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

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.

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:

https://forums.maxperformanceinc.com...1&d=1754413624

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

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.

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.

https://forums.maxperformanceinc.com...1&d=1755311731

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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. ;) :D

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.

:2cents:

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

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.

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!

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.

https://forums.maxperformanceinc.com...1&d=1755363579

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!

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

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.

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.

https://forums.maxperformanceinc.com...1&d=1755374765

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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.

https://forums.maxperformanceinc.com...1&d=1755378646

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

Dennis

You're going to have a heat crossover mismatch with any intake 71 and earlier on 72 and later heads, just a heads up if you hadn't thought about the mismatch.


Exhaust Crossover Port Matchings
With Head And Manifold Use Gasket
1965-71 1965-71 1965-71
1965-71 1972-79 1972-79
1972-79 1972-79 1972-79
1972-79 1965-71 1965-71**

** Use thin sheet stainless steel as a block off plate.

If you try the 1.65 rockers on one cylinder you would likely find that they clear ok and it’s an easy thing to check with using 3 layers of kitchen foil for a clearance check.

The more important consideration is that the factory 5/16” top thread rocker studs don’t like that added leverage loading of the 1.65s and can snap then off right where that 5/16” section starts on the stud, and especially so if polylocks are used to set the valve adjustment because they really stretch that top stud portion when the polylocks are tightened right.

Ask me how I know this !

Good that you swapped out that balancer since even though the elastermer looks ok all that oil has taken its toll.

Did they still use nylon on the timing gears in 74? If so, that might answer your question.

I'm also curious about the choke. A 68 QJ would have a divorced choke, correct? Had they changed this in 74?

Do you have a 4-bbl throttle cable and bracket? Someone I know named Mike might have been ignorant about that...


Mike

We made a lot of progress today. The new timing chain is way better. I really appreciate you all calling that one out. Poor Cole was scrubbing and degreasing the timing cover for hours and hours this afternoon. I got the more satisfying job of painting it later on. I degreased and scrubbed the front of the block and driver's side valve cover and gave them a fresh coat of paint. I'll work my way around to the rest of the engine.

I knew about the mismatch and figured we'd cross that bridge when we got there. We're almost there. Thanks for the chart.

I figured as much with the balancer. It's been soaking for years. Had a new one on the shelf that I didn't use with the GTO so that worked out.

I probably won't use the 1.65s, but it sounds like if I do I should convert over to BBC studs. Come to think of it, I have a set of BBC studs in the same box as the 1.65 rockers in storage. That's how the slippery slope begins...

As far as I read, they stopped doing nylon timing gears by '74.

A '74 intake and carb would have a hot air choke. The '68 intake and carb have the divorced type. Fortunately the intake and carb match.

About the throttle brackets...I have a '74 4bbl throttle bracket but I discovered I bought the wrong bracket for the TH350 kickdown and throttle thinking a '68 Firebird bracket would work. The '68 intake doesn't have the provision for a '74 bracket. Curious if anyone knows what I should be looking for.

'74 2bbl intake and bracketry...

https://forums.maxperformanceinc.com...1&d=1755396248

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'68 intake is missing the extra bolt hole that the '74 has...

https://forums.maxperformanceinc.com...1&d=1755396361

Starting to look like a big boy Pontiac with the 4bbl intake set on top.

https://forums.maxperformanceinc.com...1&d=1755396244

Your son has the right idea, just drive the thing. That's what they are meant for. In the grand scheme of things 100,000 miles isn't a ton of mileage and I personally wouldn't worry about a couple cylinders that pump a little less. Just bring along some spark plugs in case it fouls one or two. Looks like it might be using a little oil, again not a deal breaker. These old cars are all we drive, everywhere. I find them extremely dependable with very little that can go wrong. As long as you go over the car, and I'm sure you can do that successfully, there really isn't much to worry about. A 1200 mile jaunt is short. You can put that mileage on the car in a few weeks of driving and never leave town, and you trust it to do that right? Think of it that way.

Besides, there are plenty of us car guys throughout your route that could possibly help if the slim chance of a problem does occur. I'm in Prescott, you'll be going right by on your route. There are a few of us in Phoenix as well 100 miles south of me.

We also plan to go depending on my schedule. My issue with it last year is it really required pre-registering, which I rarely ever do for an event, and it filled up months before the event since they put a 400 car cap on the event. So I can't just decide if I can make it 2-3 weeks before unfortunately, making it a hit or miss deal if I'm going or not. I explained that to David last time I talked to him, not sure if any changes were made this year. 400 might just be the limit the track can tolerate and it just is what it is.

I do find it funny that I'm hand wringing so much over 1800 miles. He drove the car 4,000 miles over the last year with minimal issues. It looks like we'll be caravanning down with some of his friends so that will be good if something goes wrong.

I'm stumped on finding a throttle cable/kickdown mount that will work with the clip style cables on an earlier intake. I thought I could use something off a '70//71-ish LeMans with a TH350 but can't find an example of how those were set up.

I need this style for the throttle:
https://amesperf-parts.s3.amazonaws.com/FN386A.JPG

On a bracket like this with a clip in for the kick down:
https://amesperf-parts.s3.amazonaws.com/FN385S.JPG

I'd change the throttle cable to an earlier style, but the attachment at the pedal is different in '74. People do this swap all the time. There's got to be an easier solution I'm missing.

Also, something else to consider, you may need a longer throttle cable as well, I did when I converted my ‘67 from a two barrel. I ended up using an adapter from Edelbrock but many people mentioned using a piece of flat stock or even a hacksaw blade to get the additional .5 or so inch of length.

Throttle brackets are one thing about Pontiacs that can be frustrating if you just want one to bolt on easy... sometimes I have cut parts off of one added to another or fabricated a base and just used the cable hold section..

One pic is a fab from bench stock for a hurricane intake the other is 1968 intake and bracket.. but I have never done the TH-350 dance

I almost forgot, pretty sure that you can use a factory carb bracket from a mid 80’s Oldsmobile. The bracket is designed for a Quadrajet with a 2004R, I think I read that the turbo 350 kickdown cable will work instead of the TV cable.

https://www.ebay.com/itm/32594889774...xYCssOSIhRi-2A

I bought a 4bbl throttle cable from Ames. I even snagged a factory ‘’74 4bbl air cleaner. I’m hoping I can make this look as factory as possible. Shouldn’t be too hard.

What I could do is buy both brackets above and combine them to make what I need. The Olds option might be one to consider as well.