I've got an '86 Z28 with a 305 TPI. I'm thinking it ate the chain. Basically, I'm wondering if that would be an interference engine, or can I just slap a new chain in it (well, slap, as in time it correctly and then slap it) and get going down the road?

I'm borrowing my dad's car right now, and he's about to have an aneurism after one day of loaning me his car. I don't want to put a new (used) engine in it if I don't have to.

 

Interference engines wer generally Japanese, and I'm not sure they even make them anymore. You should be fine.

 

SBC V8 is an interference engine. You likely dinged some valves and/or pushrods crooked.

 

more cars are interference then not now days bud, jap, american, german it doesnt matter.

like damon said, u probably tapped some valves. u can put a chain on it and check the compression, id just go ahead and pull the heads and get them rebuilt...

o and it says ur in west tx, are u in western texas, or the town of West, TX....

 

Dang. I'll probably just end up dropping a used engine in it then. I haven't got time to rebuild anything right now.

And I'm in Western Texas.

 

It would take a lot less time to check the damage that may have been done than to just assume you need a swap.I would do a good inspection first and base my decision from there.

 

Id wait till you get the front cover off....

 

SBC V8 is NOT an "interference engine".

Last one was our 78 El Camino 305.

I cannot tell you how many of them I've had that happen, replaced the timing set, and gone happily on tens or hundreds of thousands of miles.

As quick, easy, and cheep of a repair as it is, there's no reason to get all worked up about it.

The way they ACTUALLY fail is, there's a phenolic ring molded onto a chinesium center of the cam sprocket, and the phenolic teeth just get old and brittle and turn to dust, and get stripped off of the chinesium "gums". The chain itself rarely fails.

During the process though, the cam sprocket gets smaller and smaller as it is falling apart, and by the time the chinesium is exposed, the chain is SO loose that hte sometimes wears completely through the timing cover down at the bottom pass side below the seal; so have a new timing cover on hand when you tear it down.

Replace the whole timing set as a set, you can't mix & match parts from different sets. DO NOT use a cheeeeep "truck roller" chain. If the timing set calls itself "roller" but costs less than about $45, then it's not a "roller" at all, it's BUSHINGS that just look kind of like rollers. It's GARBAGE and will "stretch" worse than a stock Link-Belt style one. Either come off the hip for a REAL roller, or just use a Link-Belt.

The job is a total piece o cake. Figure on about 2½ - 3 hours from tow-in to drive-out. Besides the timing set and a timing cover, you'll need a damper puller/installer, a puller for the crank sprocket, and some thread sealer for the lower water pump bolt on the driver's side which goes into the water jacket and therefore needs sealer on the threads.

But as advised above, before just jumping to that conclusion, what makes you think it ate the timing set?

 

If you pull the cover off & find that it has a nylon cam gear, you might want to pull the oil pan to get that junk out.
To test the timing chain, line up the timing marks at the crank. Pull the dist. cap, turn the engine back & forth while both the rotor & timing marks. Anything over 5-8* at the crank before the rotor moves is too loose.
You can pull the rocker arms off & blow compressed air into the plug holes, listen for leakage at the carb or tailpipe. If the valves are good it might even turn the engine over. I use an old compression tester (w/ the schrader valve removed) to do this.

 

Sofa- not to start an argument, but your experience with replacing chains with no other problems being encountered should not be relied on to set expectations in every case. The SBC is an interference engine and always has been, although I admit they will sometimes survive a chain failure without bending anything in the valvetrain.

Some SBCs, particularly those with small valves, small cams and heavily dished pistons, can sometimes survive a chain failure without dinging a valve. Depends on luck as much as anything. If you happen to have the cam stop near max lift on an intake, you'll ding that valve in any small block. The valve reliefs in the piston were never designed to accomodate a wide open valve at TDC.

An 86 305 TPI with flattop pistons and 1.84 intake valves.... I wouldn't bet money on it surviving a chain failure unscathed. I'm just saying that if he goes and replaces the chain based on your guarantee and then finds out there's other damage he's probably not going to be very happy about it.

 

I've changed at least a dozen of em... NOT ONE stock one has ever hurt ANYTHING...

But yeah, no sense in arguing about it.

The OP needs to do some actual troubleshooting at this point, since we haven't heard why he has jumped to this consclusion. Kinda like the guys that post on here about "gotta get my engine rebuilt because the front seal leaks", and it turns out that ACTUALLY they merely hacked the smog pump bracket off and didn't put a bolt in the leak hole. A junk bolt out of the bolt box, $0.00001 of silicone, and 15 seconds later, all is well in the world.

Dangerous to just bypass all that common-sense stuff and jump DIRECTLY TO some "mother of all repairs" kind of sob story.

 

Never seen a broken one, often the loss of timing is a big clue.
Gets hard to keep the timing set where you want it.

 

I let the shop fix it. The gear had several teeth eaten clean down. The rest of them were very badly worn. I was surprised to find that it was made entirely of aluminum. It was replaced by a phenolic/chinesium miracle of modern engineering. the chain was fine, if not slightly stretched, but I had them put a new one in anyways.

The engine went back together with little problem (the timing cover gave a little bit of trouble because they didn't drop the oil pan), and when all the fluids were filled back up, it started and ran fine. Well, it was a bit noisy, I think a rod may have been bent slightly. I need to take a look at that. They started to tinker with the ignition timing, but the weight on the harmonic balancer must've shifted about 30-50 degrees because the engine would not run with the notch at 6 degrees before TDC. I need to make a new mark on it at TDC so I can time it properly and get some power back.

I lucked out, in that, no valves seem to be damaged.