Bent Pushrods

[Harry Dawg]

Might be worthwhile to survey the AMC forum posts regarding these engines. I understood these engines were considered smooth, reliable and durable in their day; no obvious weaknesses. If the oil pressure and compression were good, I'd close it up and attribute your issues to abuse by the previous owners.

Yes. I have heard the same thing. My cousin said you could balance a quarter on the air intake it ran so smooth.
I am sure that's a bit of a stretch lol.

However, I would say that this plastic timing gear is an obvious weakness. The only thing I can think to explain this is AMC engineers were eager to experiment with new synthetic materials that were lighter, cheaper and easier to manufacture than traditional steel parts. Perhaps they just didn't foresee the lack of reliability.

That being said, the first synthetic material, Bakelite, was invented in 1907. Nylon came around a few years later in 1935. They had at least 30 years of experience with synthetic materials and should have seen the potential pitfalls of this design, as it could be a potentially catastrophic and easily avoidable failure.

[tgreese]

Quieter.

[Yeller]

Buick and Pontiac had the same issue, not sure when but a lot of engines suffered an early death over plastic timing gears

[stjohnspock]

I had a 69 Buick Skylark with the Buick 350 back in the day. Revved it up once and blew the nylon off a portion (sector) of the cam timing gear. The nylon (or whatever plastic it was) turned out to be a thick coating on top of the metal teeth--not the whole gear. Of course when some of that plastic flew off the chain became loose whenever that damaged portion had the chain on it--TAK, TAK, TAK.... And yes, the plastic coating was there to make the timing set run quieter. A good idea when cars only lasted six years or so....

[tgreese]

Yeah, the hub on the 225 cam gears from this era were aluminum, with nylon teeth as a ring around the outer diameter. Frequently failed around 100K miles. Many owners changed to an iron gear preemptively - common upgrade. I presume the other Buicks of the era were the same.

[Harry Dawg]

Results of the compression test.

(1) - 150. (8) -147
(3)-150. (6) -148
(5)-153. (4) - 148
(7)-149 2)-150

I'd say that's good enough for who it's for.

I also installed a gauge set so I could test for oil pressure and have in cab coolant readout.

Not any oil flow through the rockers during compression testing, but it probably isn't building enough oil pressure to get to the top of the motor.

Valve train seems to be functioning as intended.

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[Harry Dawg]

Finally got everything back together.

I ended up taking the rocker shaft off and cleaning it with some PB blaster. There actually wasn't too much sludge in there, but I didn't take the rocker arms off. I watched a guy on YT break his when trying to disassemble, so I was wary of making the same mistake. https://youtube.com/watch?v=bMm8rVY53lY&t=215s

I also painted the valve covers and relocated the ignition coil while I was in there.

Fired it up, and still have a top end tick!

It does run better (it doesn't seem to "skip" / misfire like it did with the bent pushrod) It hits consistently every time.

At this point I am thinking it's a lifter. Probably one of them is blocked with sludge and can't get any pressure. I ordered a new set on RockAuto and will throw them in next weekend.

On the topic of oil, it did have very good pressure (around 50 PSI according to the gauge). I'm taking that with a grain of salt given the set was only $40.

YT link to the project video for reference. https://youtu.be/b-_SUgtijpI

*Unrelated ramblings on the radiator below - Read at your own risk.

I was going to rod the radiator while I had it out, but I ended up screwing up the core when I was trying to take the tank off.
It was pretty shot, so I didn't have much to lose (or so I thought).
Then, I ordered a CJ aluminum radiator, which others have had success with in the 1st gen Gladiators.
However, this will not work if you have power steering. The water outlet is positioned higher on the CJ radiator and the lower hose needs to go where the power steering belt is.
Coincidentally, my CJ7 needs a radiator so this kind of worked out.
Finally I broke down and took the factory one to a shop, where they re-cored it (for $550). Honestly a fair price given how big of a PITA radiator repair is, but that one still hurt. Especially considering a new one from BJ's would have only been $600.
They also put the tank straps on the wrong sides, so I had to take it back a 2nd time. The better part of a weeks pay and 3.5 hours of drive time, and it's finally back in the truck.

[OldFarmTruck22]

Great work! Just a suggestion, if it were my truck I would remove that glass fuel filter from that location and have as much steel line down there as possible. IF that glass filter cracks or breaks while running or shut off hot right in front of the exhaust, you are looking at an engine fire or explosion. I would have the fuel filter up closer to the carb where you can monitor its condition, and I would switch to a STEEL filter. Just a helpful suggestion. Glass fuel filters have fried a lot of cars.

[Harry Dawg]

Thanks for the feedback OldFarmTruck22.

I have been thinking of this myself. The exhaust crossover running right below the fuel pump is kind of a safety hazard.

Plus, my tubing flare tool won't work on the 3/8 fuel line, which is why I have all of the rubber hose connectors.

This was mainly a test system since the old fuel line was rusted out, and I just never fixed it correctly.

I think I will swap over to flexible braided line with AN fittings from tank to the fuel pump, and then a single hard line to carb.

The fuel system is brand new, so I can just ditch the glass filter all together.

[Harry Dawg]

Got the valley cover off today and had a look at the lifters.

Not sure how to identify if one is faulty without taking it out, but I'm thinking one of the lifters in the photo isn't pumping up.

That's where the noise is coming from at least.

These rockers also seemed to have excessive lash. About .026".

I didn't torque the rocker shaft all the way to 60 Ft. Lbs. because it felt like I was about to shear the bolt off.

About 50 Ft. Lbs. was all I could get out of it.

Maybe that's the issue and not even a lifter.

Either way, I've got a brand new set of lifters to put in it, which leads me to my next topic.

They are flat tappet lifters, and I've heard horror stories of people rounding off cam lobes when putting new lifters with an old cam.

Not to mention there is significant evidence that shows a lot of new lifters have machining issues.

But IF the lifter collapsed, it will eat up the cam too!

Danged if I do, danged if I don't.

I called it quits for the night, but I'll be back at it tomorrow.

Edit*

I re-watched the video and the rocker with excess lash is the same one that bent a pushrod.

Seems like things are starting to add up. It could be on the lifter side, or it might be the rocker is jacked up or the shaft is bent.

Right now lifters are easier to come by than rocker shafts, so I'll start there.



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[Srdayflyer]

it is nor recommended to install new lifters with and old cam, Question how many miles are on the vehicle, i assume you are nor the orig. owner so the question is how many mile are on the motor, 1. you can assume that the true mileage is unknown. 1 or more cam lobes are out of spec. and are causing lifter/ tappet noise. there should be zero lash on the tappets as the internal check valve holds oil , unless the vehicle sits a long time then bleed down may occur, it is a job that requires lots of part removals the bright side is you will be able to determine timing chain wear, condition of the timing chain cover/oil pump housing, fuel pump lobe, water pump condition , the distributer gear should also be replaced with a new cam install, up side is you can pick a cam that will give you a bit more power vs stock OEM profile cam, just the things i would do and look at this is not a time to step over a dollar to pick up a penny, just my opinion and 2cents.

[Srdayflyer]

another question did this vehicle sit a long time ? is this a new vehicle for you? it may if it sat a long time may have had oil bleed down into the cyl. and may have been enough to cause hydro lock and not allow the valve to open and bend the pushrod, excessive hydro lock and you can bend con.rods only you can answer those questions

[Harry Dawg]

I am the second owner. The first was my Great Grandpa, so I do know the vehicles history.

The odometer shows 36K miles.
I am guessing that is 136K.

I just did the timing chain because I thought it jumped time, and that is what caused the bent pushrod.

When I went in there, it had already had a timing set done once, and it wasn't out of spec. I replaced it anyways, and saved the old one for spare parts.

I was going to replace the cam, but there are no NOS or aftermarket OEM spec cams available. My options were to get one out of a parts truck or have one custom ground. (Assuming someone had a cam blank for a 327). Neither sounded appealing, so I decided to roll the dice.

The vehicle did sit for a long time, but the clattering just started recently.

Good point on bleed down though. I only ran the truck for a few minutes after it sat for 5 months with no oil in the crank case (Took me a long time to get the timing set done and everything reassembled. Life doesn't stop for FSJ'rs lol)
Maybe I should have ran it longer to see if the lifter would have pumped up.

I think what I will do now is take each lifter out individually and inspect 1) the tappet contact face and 2) the cam lobes.

If that everything looks good, I'll press the plunger with a screw driver and see if it comes back up or stays down.

It might be that the cam is worn and I'll just have to deal with valve train noise until I rebuild it.

[seventynine]

Hmm…this a tough one. You are in pretty deep here. That motor looks pretty crusty and sludgy. I don’t know anything about the AMC 327 but it sure looks like a candidate for a rebuild…but it sounds like parts are scarce. On the up side, your compression and oil pressure seem ok. Maybe put it back together and put loud stereo in it and run it until you can’t

[letank]

I didn't torque the rocker shaft all the way to 60 Ft. Lbs. because it felt like I was about to shear the bolt off.

About 50 Ft. Lbs. was all I could get out of it.

Sorry, I do not have the 327 TSM handy, but for the 360 it is 19 Ft/Lbs.... I did a similar error and skipped the specs line... to another value around 50ish and only stretched the bolt... I managed to get a few spares from one of the forum seller...

Otherwise, it is a lot of sludge, curious which oil was used, I have worked on a few engines, but none were so sludgy with over 200K.... on original engines

As for the lifters, I replaced Only the lifters on the 74 when one went off at 180Kmiles when it was my DD, no time to waste on an overhaul in those early years ... it is still running at 349Kmiles or 25 years later ... not too often but still a smooth idle

[Harry Dawg]

@Seventy Nine - It 100% needs a rebuild lol.

I am just kicking the can down the road mainly due to space.
Right now I'm working out of a 2 car garage, and the other bay has my CJ7 in it.

Parts are also somewhat challenging to come by, but the main consumables (rings, bearings, gaskets, top end parts) are all available on Rock Auto. It's mainly things the core parts like camshaft, piston, rocker shafts, etc that are hard to come by.

It already screams like a mountain cat with the Cherry Bomb X-Treme, so I don't hear a thing on the road .

Whatever the case, I'm gonna keep her going until the old 327 is flat out done.
Maybe it'll hold out until I can get some shop space.

@Letank - The TSM calls for 60 LBS, which seems very high to me. However, the rocker shafts where on there very tight when I took them off. This indicates that 60 is probably the correct torque spec.

It's not going to get it though, as i'd rather deal with a tick than a sheared off bolt that will be nearly impossible to come by. Also it could ruin the head IF it were to shear off.

My hypothesis is that the oil bath air cleaner is to blame for all of the sludge. The large particulates fall down into the crank case to prevent clogging the air cleaner.

Interesting idea on paper, but not so great for longevity.

Good to know on the lifters. The old ones are coming out today or tommorow which will help determine next steps.

One other thing I plan to do is check the cam-lift using a dial indicator. This will give me a better idea of cam health without pulling the dern thing.

[Srdayflyer]

boy o boy, I haven't seen an engine block treated with glyptal (the red coating) in decades like since the 60's, they use that to allow oil to run back to the pan and prevent sludge build up, its nice to see they did things proper back in the day, they still sell glyptal but you have a hard time getting a good job like that by hand ,, since you got the big chunks of the plastic gears out any real small pcs probably passed thru long ago imo.

[Harry Dawg]

@Srdayflyer
Interesting. And here I was thinking it was just spray paint or something.
I guess it does make the casting more smooth so the metal doesn't hold onto the oil as much.
Don't know how much it helped in the long run though lol. It still has a lot of sludge build up.

After careful consideration, I have decided not to replace the lifters.
I took the rocker shaft off and pressed the push rods into the lifters and all of them still return as expected.
Plus, I couldn't get them out of the top side, so the cam will need to come out to replace them.
Hopefully the noisy one will quiet down after driving it.

And it sounds like I have a 50-50 chance of wiping out the old cam with new lifters anyways.
I should have just done the cam when I replaced the timing chain... Hindsight is 20-20...

[tgreese]

Glyptal is a bright red thick enamel originally intended for coating copper windings in motors, transformers, coils, etc. To be effective as intended, it needs to be a thick coat that fills in the porosity in the cast iron. As noted, it's hoped that the smooth surface sheds oil and the valley oil drain-back becomes faster/better. Correct it was used in the past to coat the rough interior cast iron in motors, typically by hot rod builders prominently featured in hot rod magazines, possibly for greater photographic impact.

Can't believe Glyptal would make much difference outside a racing/competition environment, or why you couldn't create the same benefit by adding a few extra ounces of oil to the sump. If it has anything to do with sludge buildup, modern detergent oils will make that totally moot. Indeed, IMO with detergent oils, any coating on the bare iron seems dumb, considering the risk it will flake off and get into the oil system.

This looks like paint to me. Normally, the engine would only be painted on the outside, since the inside is both hidden and bathed in oil. Seems more likely that some amateur mechanic painted the interior because of some personal aesthetic thing. Or maybe AMC painted the raw block before machining. Seems unlikely, but maybe. This is a 1st gen V8, and possible they had not optimized such things.

[Harry Dawg]

I can almost guarantee my Great Grandpa wouldn't have gone through the trouble of painting it, if he was even in there at all.

He drove this truck hard and put it away wet, and it shows.

Could be a shop did it though. Who knows.

Anyways, I put the valley cover back on. Made a nice cardboard gasket instead of buying one for $35.

At this point the engine needs a full rebuild, so I'm not going to waste the coin on gaskets.

Case in point, I noticed the valve on the right has some abnormal wear patterns. Seems as though this rocker may not have been oiling.

It actually wore a divet into the valve, and you can see the light reflecting off it.


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