Worn cam lobe... what would you do?
01-18-2018, 07:46 AM
#1
Melting Slicks
Thread Starter
Worn cam lobe... what would you do?
Hey All,
I have a relatively nondescript 350 with 882 heads. The idle seems smooth enough, oil pressure is very good and so is compression at 160-165 PSI. Yet while I was setting the lash running, I noticed that #8 intake was not rocking as high as the rest. It also had the lowest compression reading at 155 PSI. At higher RPM there seems to be a vibration, but it is hard to tell...
What would you guys do with this while waiting to drop in another motivator?
Drive it as is? (It might take 10 months to 2 years before I replace it with a fresh engine)
Swap in a new cam + oil change? (EDIT + new lifters of course...)
Going through the short block seems like investing too much into something I will eventually replace...
I have a relatively nondescript 350 with 882 heads. The idle seems smooth enough, oil pressure is very good and so is compression at 160-165 PSI. Yet while I was setting the lash running, I noticed that #8 intake was not rocking as high as the rest. It also had the lowest compression reading at 155 PSI. At higher RPM there seems to be a vibration, but it is hard to tell...
What would you guys do with this while waiting to drop in another motivator?
Drive it as is? (It might take 10 months to 2 years before I replace it with a fresh engine)
Swap in a new cam + oil change? (EDIT + new lifters of course...)
Going through the short block seems like investing too much into something I will eventually replace...
Last edited by DorianC3; 01-18-2018 at 07:50 AM.
01-18-2018, 08:05 AM
#2
Drifting
First verify it is a worn cam and not a bent pushrod. If cam is wiped, do not operate further. Pull cam and lifters and drain oil. Thoroughly flush engine. You may save engine. Get a new cam and lifters and get rid of those 882 heads. When finished you may like it well enough that you'll forget about changing engine.
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DorianC3 (01-18-2018)
01-18-2018, 08:28 AM
#3
Melting Slicks
Thread Starter
First verify it is a worn cam and not a bent pushrod. If cam is wiped, do not operate further. Pull cam and lifters and drain oil. Thoroughly flush engine. You may save engine. Get a new cam and lifters and get rid of those 882 heads. When finished you may like it well enough that you'll forget about changing engine.
01-18-2018, 08:39 AM
#5
Melting Slicks
Thread Starter
No, none at all. It is quite smooth. Overall it runs quite well. Just the higher rpm feels uncomfortable. I do hear what sounds like a ticking sound with a stethoscope. I can't seem to locate it precisely.
01-18-2018, 10:32 AM
#6
Le Mans Master
If you do in fact have a lobe going away, the damage has already been done. All that metal has gone through the entire engine and is embedded in the bearings. It may last a little while but it depends on how many miles and how hard it's driven. I saw your other post about performance launches.
01-18-2018, 10:57 AM
#7
Melting Slicks
Thread Starter
If you do in fact have a lobe going away, the damage has already been done. All that metal has gone through the entire engine and is embedded in the bearings. It may last a little while but it depends on how many miles and how hard it's driven. I saw your other post about performance launches.
Yes. That was rather more theoretical. Mostly exploring how the hell one gets off the line gingerly with such a short box. ;p
Under my watch, this car has never seen 4000 rpm and rarely even sees 3000. Not until I know more about its health. That and 95% of the time I drive like a grandma.
When bringing it up in rpm at 60 mph is when I became suspicious. At 2500-3000 rpm it didn’t feel as smooth as I was expecting.
I’d agree with you on the trashed innards if a lobe went... but now I’m suspecting a bent rod. If this was a cam lobe, it should have been completely deteriorated by the time I took ownership. I doubt the seller could have gotten away with that. Tho not perfect, the operation feels too smooth
Last edited by DorianC3; 01-18-2018 at 10:58 AM.
01-18-2018, 10:59 AM
#8
Safety Car
If it is the lobe and it sounds like it is, you can roll the dice with a new cam and lifters but as stated before, that worn metal went somewhere. Hopefully in the oil filter.
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DorianC3 (01-18-2018)
01-18-2018, 11:15 AM
#9
Melting Slicks
Thread Starter
stay tuned !!!!
01-18-2018, 12:42 PM
#10
Safety Car
Member Since: May 2004
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My experience - I lost the fuel pump lobe, completely rounded off. That is a lot of metal. Put in a new cam and ran it for years hard. I would think that metal gets into the sump where it first goes through the oil filter. Not knowing what was going on, I never opened up the oil filter, but I did change my oil quite regularly. If it's not a bent pushrod, I would suggest you drain your oil to have a look and have it analyzed. Look at the filter too. I wouldn't be afraid to change out the cam at that point and keep running, especially as how you've described your driving habits.
One last thing about a wiped lobe, I blame Mobil 1 with not enough ZDDP. This was however ten years ago.
One last thing about a wiped lobe, I blame Mobil 1 with not enough ZDDP. This was however ten years ago.
Last edited by ignatz; 01-18-2018 at 12:47 PM.
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DorianC3 (01-18-2018)
01-18-2018, 02:06 PM
#11
Melting Slicks
Thread Starter
Interesting. These heads look like they have been rebuilt very recently. They look very clean. No wear pattern on the valve tips. The rocker studs are the screw-in type; that’s not what is supposed to be on 882 heads.
I put a vacuum gauge on the running engine and got a very stable 17 inches. With the engine running, I could see the pushrods spinning. Though #8 exhaust was spinning slightly slower.
Pushrod #8 exhaust is bent, but slightly. Spinning it in a drill one can see a slight wobble that the pushrod right next to it does not have. Nonetheless (and bear with me) I do not think this is enough to explain the lack of lift. Hmmm. I’ll have to see if I can find a dial gauge somewhere this weekend. That or I may pull the intake and eyeball the bottom of the lifter directly.
01-18-2018, 02:08 PM
#12
Melting Slicks
Thread Starter
My experience - I lost the fuel pump lobe, completely rounded off. That is a lot of metal. Put in a new cam and ran it for years hard. I would think that metal gets into the sump where it first goes through the oil filter. Not knowing what was going on, I never opened up the oil filter, but I did change my oil quite regularly. If it's not a bent pushrod, I would suggest you drain your oil to have a look and have it analyzed. Look at the filter too. I wouldn't be afraid to change out the cam at that point and keep running, especially as how you've described your driving habits.
One last thing about a wiped lobe, I blame Mobil 1 with not enough ZDDP. This was however ten years ago.
One last thing about a wiped lobe, I blame Mobil 1 with not enough ZDDP. This was however ten years ago.
Ignatz, I may well go that direction. Hmmm
01-18-2018, 02:14 PM
#13
Melting Slicks
Thread Starter
I’d say there is 1/32 to 1/16 deflection
01-18-2018, 03:37 PM
#14
Advanced
I don't know if this will help but keep in mind that if the pushrod is bent that it will flex when the engine is running and the lift will be affected. I would follow the excellent advice given here and investigate further. My advice is if the cam is going flat: replace the cam and drive the car. Even if you are going to replace the engine in the future having a car that you can't/don't want to drive will eventually turn it into a piece of garage art that you resent having to work around. I would also just put a stock cam back into it if you really intend to replace the engine. If you start to upgrade the cam you will have to upgrade other components and that is a slippery slope that we have all been down. P.S. I am a hardcore hot rodder so you should take that into consideration when I say to stay stock in this instance. LOL
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DorianC3 (01-18-2018)
01-18-2018, 03:39 PM
#15
Race Director
A bent pushrod would be clacking up a storm.
01-18-2018, 03:52 PM
#16
Melting Slicks
Thread Starter
I don't know if this will help but keep in mind that if the pushrod is bent that it will flex when the engine is running and the lift will be affected. I would follow the excellent advice given here and investigate further. My advice is if the cam is going flat: replace the cam and drive the car. Even if you are going to replace the engine in the future having a car that you can't/don't want to drive will eventually turn it into a piece of garage art that you resent having to work around. I would also just put a stock cam back into it if you really intend to replace the engine. If you start to upgrade the cam you will have to upgrade other components and that is a slippery slope that we have all been down. P.S. I am a hardcore hot rodder so you should take that into consideration when I say to stay stock in this instance. LOL
Thanks. It does help. And I agree. I’d MUUUUICH rather this be a running project. This weekend I’ll investigate further. (It’s nearly 10 pm here). If it is a wiped cam lobe, I’ll replace the cam and lifters and be done with it. This only needs to last 12-24 months... and be comfortable during that time. In the meantime I need to save up for a good crate or similar
On a 1969 ‘vette, can the cam be replaced in the car or should one pull the engine ?
How does one flush the engine as mentioned above?
On a 1969 ‘vette, can the cam be replaced in the car or should one pull the engine ?
How does one flush the engine as mentioned above?
Last edited by DorianC3; 01-18-2018 at 03:55 PM.
01-18-2018, 03:53 PM
#17
Melting Slicks
Thread Starter
01-18-2018, 03:59 PM
#18
Safety Car
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2021 C1 of the Year Finalist - Modified
I would bet on a bad cam-get it out of there asap. However, many years ago right after I got married all I could afford was beater cars. I would pay $75 to $150 for a car with an inspection sticker and run it till it died. I bought a big 72 Pontiac 4 door , V-8 car. Cam went bad on one cylinder. Pulled the push rods and drove it for 2 more years, then off to the junkyard. It ran rough but it ran !
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DorianC3 (01-18-2018)
01-18-2018, 04:11 PM
#20
Melting Slicks
Thread Starter
i would bet on a bad cam-get it out of there asap. However, many years ago right after i got married all i could afford was beater cars. I would pay $75 to $150 for a car with an inspection sticker and run it till it died. I bought a big 72 pontiac 4 door , v-8 car. Cam went bad on one cylinder. Pulled the push rods and drove it for 2 more years, then off to the junkyard. It ran rough but it ran !
lolololol.