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1100 hr valve job and........

Bob H.

Bob H.

Contributing Member
Got the 381 laid-up in heated storage this winter and did a compression test on both engines (454 model 350). Starboard engine looked good with seven cylinders at or near 150psi and one at 139psi. Port engine was another story; two cylinder at 90psi, five at 120 and one at 60 psi! Cylinder leakdown test shows a bad head gasket and a couple of leaky intake valves.
My question is this; should I be concerned about the lifters and camshaft with these issues and hours? Can I get an accurate read of camshaft wear (dial indicator) before teardown with these existing issues?
Thanks in advance,
 
My opinion is to replace the cam, lifters, and chain at this point. Cam bearing wear out is rare. I don't think you can rely on these parts to make it to 2000 hours, and replacement requires the heads to come off (again). These engines are not known for particularly favorable cam wear, especially with a lot of low speed, trolling operation. And, the wear is not linear with age, it can come quickly. If the bores look OK at teardown and have in spec taper, you can keep this to a top end job.
On the other hand, if engine/boat clearances don't allow the cam to be pulled out in place, I'd rethink that idea.
 
Why on earth rip the motor down to replace a (probably) perfectly good, thoroughly worn in camshaft and lifters? The blown head gasket needs replacing, of course, and it's a good time for a valve job while the heads are off, but I'd stop there.

Jeff

PS: Two cautions: Even assuming this is a roller cam motor, you still need to keep the lifters in order, so you can put them all back where they came from. Also, where that head gasket was leaking, inspect the block surface CAREFULLY to see if it's 'fire-gouged' where the leak was. If so, all bets are off for the block has to be resurfaced. Ugh1
 
You can measure the cam and assess (to some point) how much wear it has experienced...a big unknown is the maintenance done on the engine...as far as rules of thumb, a top end job @ 1000 hours and a major overhaul @ 2000 hours were the norms we used in the boat shop years ago...so needing to recondition the heads on your engine is in the "expected" window. The lifters can be inspected as well but are relatively cheap to replace.
 
Thanks everyone! I appreciate the input. Tear down starts next week. All I want for Christmas is a good machine shop!
 
Bob H. said:
Thanks everyone! I appreciate the input. Tear down starts next week. All I want for Christmas is a good machine shop!
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Lake Worth Crank and Machine.
They are great, and know marine to funny car big blocks too. They were so proud of a race engine there that gets about 20 seconds life between overhauls. :eek:
 
Having once been in the camshaft business I get it as to why used lifters should go back in the same hole (tolerance stacks cause differing wear patterns). But most sources say that rockers and pushrods should also not be mixed. I can't think of a good reason why, particularly with the pushrod, and I have been in several shops where pros just throw pushrods and rockers (and their hardware) in a box until reinstallation. Anyone have experience with this issue?
CaboJohn
 
diver_dave said:
Lake Worth Crank and Machine.
They are great, and know marine to funny car big blocks too. They were so proud of a race engine there that gets about 20 seconds life between overhauls. :eek:
Click to expand...

That's the kinda shop I want! Too bad they are not local: shipping charges would be more than the job!
 
CaboJohn said:
Having once been in the camshaft business I get it as to why used lifters should go back in the same hole (tolerance stacks cause differing wear patterns). But most sources say that rockers and pushrods should also not be mixed. I can't think of a good reason why, particularly with the pushrod, and I have been in several shops where pros just throw pushrods and rockers (and their hardware) in a box until reinstallation. Anyone have experience with this issue?
CaboJohn
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Great question! I'm pretty good at organizing my projects but was pondering if/why I should do that also. I could take the dremel and scratch on identifications for every rocker/rod/stud nut but.......yowza!
 
CaboJohn said:
Having once been in the camshaft business I get it as to why used lifters should go back in the same hole (tolerance stacks cause differing wear patterns). But most sources say that rockers and pushrods should also not be mixed. I can't think of a good reason why, particularly with the pushrod, and I have been in several shops where pros just throw pushrods and rockers (and their hardware) in a box until reinstallation. Anyone have experience with this issue?
CaboJohn
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I have only a guess. If the surfaces are only case hardened the metal has little depth of wear resistance. The break-in process of mating two, surface hardened parts will necessarily remove some high spots. It this is attempted multiple times, you may wear through the hard areas into the base metal, causing very high material loss through the softer material.

To the OP: If you can get your fingers on your cam lobes, feel for any ridge across the high sections. If your fingernail catches, that lobe is not long for this world. But, I don't think you can do this in place on a Gen IV 454. Too deep into the block with good top access blocked by the casting.
 
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diver_dave said:
To the OP: If you can get your fingers on your cam lobes, feel for any ridge across the high sections. If your fingernail catches, that lobe is not long for this world. But, I don't think you can do this in place on a Gen IV 454. Too deep into the block with good top access blocked by the casting.
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Great tip! I'll be getting into this next week and will follow-up/post pics.One good thing so far; except for the height restriction, the engine room in the 381 provides plenty of room for this project!
 
Unless you do this stuff a lot you would be wise to take a lot of digital pics of everything from your distributor rotor position to how the carbs hook up to.....well you get the idea. Nothing nicer when you have a mystery wire or clamp or whatever than being able to look at a "before" picture and see where it belongs. Also a 50 pack of sandwich bags and a sharpie can keep everything sorted and organized and make reassembly easier. +2 on those that said leave the cam and lifters alone for now. And I don't believe that if you go back later to change the cam you will have to remove the heads again (absent a catastrophic failure that demands a complete rebuild).
CaboJohn
 
CaboJohn said:
And I don't believe that if you go back later to change the cam you will have to remove the heads again (absent a catastrophic failure that demands a complete rebuild).
CaboJohn
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You are correct. I stand corrected. Only the intake manifold, valve covers, and timing chain cover need be removed. And rocker arms loosened.
 
Plus the fact that I have a complete, fully functional twin sitting next to me while I do this job gives me a comfort zone too! The camshaft discussion/input from everyone has also been very valuable to me. I'm mechanically oriented (retired after 35yrs as an industrial electrician/welder), but feedback and tips from guys who have and are earning their living doing it is priceless. Thanks again everyone!
 
Bob:

Those 454 motors have a reputation for sucking water in through the exhaust valves--too much valve overlap or something. If so, the exhaust valve stems tend to rust and stick, which burns the valves and lowers the compression.


Question: Eyeballing the exhaust ports, did you see any sign of rust?

Jeff
 
fastjeff said:
Bob:

Those 454 motors have a reputation for sucking water in through the exhaust valves--too much valve overlap or something. If so, the exhaust valve stems tend to rust and stick, which burns the valves and lowers the compression.


Question: Eyeballing the exhaust ports, did you see any sign of rust?

Jeff
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I won't be able to get a look until later this week Jeff, but I will definitely investigate for this!
 
Well after a brief hiatus (holidays and new grand daughter!) we are back on this project. Got the exhaust manifolds/risers off today and found out a few things; those suckers are heavy! And I'll be replacing hoses and hardware too. But so far except for one seized bolt this went well. I'll post pics and hopefully more progress tomorrow!
 
CaboJohn said:
Having once been in the camshaft business I get it as to why used lifters should go back in the same hole (tolerance stacks cause differing wear patterns). But most sources say that rockers and pushrods should also not be mixed. I can't think of a good reason why, particularly with the pushrod, and I have been in several shops where pros just throw pushrods and rockers (and their hardware) in a box until reinstallation. Anyone have experience with this issue?
CaboJohn
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John, I don't recall having seen a machine shop keep push rods and rocker arms in any certain order for re-assembly. All of these become readjusted anyway.
However, this is not a suggestion that we DO NOT inspect these parts.


I agree with Chris.... if this engine uses a roller cam/roller followers, leave them alone (unless you have other suspicions).
A GM roller cam/roller followers will often go 200K miles in a car/truck and still be OK.
The Marine engine camshaft work load is not all that different.


.
 
Thanks Rick. I agree. All my experience is with Chevy based blocks and I don't worry about keeping push rods and rocker arm stuff in order although you don't have to look hard to find "experts" that say it is important.

Good weather down here right now and the boat is running well (other than the usual, changing list of small problems). Hurricane damage on the boat was minimal. Caught a nice dinner size (15 lb) Mahi yesterday and a really nice Marlin that tried to beat me do death with his bill as I worked at getting him unhooked. No real damage to either of us however.

CaboJohn
 
Good to know because that's job # 1 tomorrow before the heads come off! Going pretty smooth for working in cramped spaces. Don't see any visual valve train damage so tomorrow should tell the tale.
Cabo John I'm jealous! Our Lake Michigan salmon and trout behave quite well once we git 'um into the boat!
Thanks for the input and comments everyone, keep them coming1
 
Heads came off today! Definitely showed traces of a leaky head gasket on the two low compression cylinders.
In addition, I'm also the proud owner of two seriously damaged piston heads/tops. I'll post pics as soon as I figure out how, but this is abit of a surprise! This engine that ran well; we started this investigation because of a loud valve/engine noise but even with that it did not over-heat or run rough.
Is it possible that this could be previous damage that the original owner didn't disclose and decided not to fix?
 
Pics; CEF 1.jpgCEF 2.jpg The rest of the piston tops/heads looked pretty normal.
Off to the machine shop tomorrow to see what their opinion is. In a perfect world I would have the time and resources for a new long block. That's just not gonna happen this year.
What are my chances of re-conditioning the heads, putting her back together and if she shows decent compression, running her gently for a season? Or two?
 
that don't look good....and something looks radically different in that second pic...a pic of all four holes on that side would help....and what about the other low cylinder? how did the heads look?
 
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