Questions for engine guru's

[sope]

I have several engine questions. I have an 87 TBI 305 with about 175,000 miles on it. I'm still running 10W30 in moderate temparatures. Engine runs good and doesn't burn much oil. It has been maintained well for the last 100,000 Miles. It is in my truck wich is primarily a trail rig now.

1) It has just recently started ticking out of the right bank only after several minutes of high load and high RPM. (Usually 4 low on climb). The tick goes away after I take it easy for a couple minutes. I believe this to be a collapsing lifter but it also could be sticking. Any opinions?

2) If I replace lifters I will likely replace the cam. I would like to give it a little more go, low end preferably. I'd like to keep this simple without rechiping.(money's a little tight) Can I do this or should I just inspect it and go with the stock one if needed.

3) Anybody know if this engine has plastic or metal teeth on the chain?
I't's not rattleing but it's probably time.

Any opinions are appreciated.

 

[dyeager535]

Cam is pretty "iffy". ANY changes really need a chip burn to get the absolute most out of it, but of course the benefits vs. cost on that aren't always there. It's not like it's going to explode with a tiny bit more lift. That needs to be read carefully...it doesn't say you HAVE to get a chip burned, just that it needs done so it would run as good as possible.

You might try TBIchips.com, see if there is anything recommended there for no-chip burning needed cams. I guarantee with as much chip experience as Brian has, if anyone can tell you based on actual data, it will be him.

Teeth will be nylon coated. Double row/roller won't hurt. Eventually the nylon will wear enough that they will fail.

 

[Mike D]

You might be hearing octane knock. The oil companies are adding 10% ethanol to a sub regular (84.5 octane) base fuel. The net result is 87 octane but under high loads the engine may run too lean. Next time you go 4 wheeling try a mid grade gas (89 octane). If that noise doesn't occur then it's the gas, not the engine.

 

[roadnotca]

I haven't done this myself, so take it with a full shaker of salt. You may have a lazy lifter. The tip I've read is to perform a valve lifter adjustment, but while you're doing it, remove the rockers and drop a little bit of spray carb cleaner down the center of the push-rod.
I recommend an oil change once it's up and running again, and fully warmed-up.

 

[4X4HIGH]

I recommend doing an oil change and adding 1 quart or ATF and the rest oil. The ATF is a detergent and will clean sticky lifters. The ATF will not hurt the engine and can be left in until the next oil change.

The cam should have a chip burn if it's anything other than a stock cam. Yes there are cams that will work without burning a chip but you won't see the full benefits of the cam swap without a matching chip burn.

The later truck engines (87-on) came with steel cam gears from the factory and no nylon teeth like the car engines had.

 

[sope]

Thanks. I'll try an additive or ATF. Just seemed weird that it only happens after extended high rpm. It is a single valve noise not a ping.

 

[dyeager535]

Well heck. If the truck timing setups are metal, I'd probably not ever worry about one wearing. Stock with NYLON will run well over 100,000 miles, without having to worry about that wear, gotta be near engine life before it needs to be swapped?

 

[sope]

Chains still stretch and jump teeth.

 

[dyeager535]

Of course they stretch, question is, how much?

I've yet to see or hear of a chain that stretched so much that it allowed the chain to "jump teeth". Look at a timing setup, and how many teeth engage the chain at a given time. The chain would have to have probably a 1/2" or more slack to possibly jump, since it would have to skip over almost half the teeth on the gear at one time, to the height of the "top" tooth at any given time.

Certainly the chain will affect accuracy of timing, as loading/unloading would change the tension on a loose chain moreso than with a tighter chain. You can see this effect even on tight belts while the engine transitions from high to low RPM or vise versa.

Not saying it's something that should be ignored in a rebuild, more just going after the "jumped a tooth" myth. If it jumps a tooth, it's going to jump all of them, all the time, meaning the engine will never continue to run. BTDT.