Retsik

This is going to be a long one, but I wanted to provide everybody as much detail as possible in order to help me diagnose what I did...

This week I did a cam install (Thunder Racing 224/224/112) on my 2001 SS M6, complete with TR pushrods, Comp Cams 918 springs and titanium retainers. After I bolted everything up (torqueing everything to specs) and tried to start the car, it didn't sound right as it was cranking. The engine never started, and since the sound of the cranking sounded so odd (it kinda "whirred"), my first thought (after verifying everything was connected) was that I somehow botched the alignment of the cam/crank sprockets.

After biting the bullet and pulling off everything down to the timing chain, I rotated the crank (by using a ratchet/socket on the crank bolt) until the dots lined up. Sure enough, all looked well. Just for giggles, I rotated the crank some more and saw that there was yet ANOTHER dot on the other side of the crank sprocket.

By this time, it was getting to be really late and my neighbor stopped by to give me a hand.

Here's where I fugged up...

Listening to a suggestion of my neighbor, we rotated the crank until the dot on the cam sprocket was on the very bottom. We then removed the timing chain and began to turn the crank (in order to align the other crank dot with the cam dot). I was holding the timing chain off the sprocket and my neighbor was turning the crank (with some pretty good force). It was at this point I heard a deep thunk... I knew immeditatly that something broke inside.

I looked up and in our rush realized that I never pulled the valve covers and pushrods out before doing this!

Trying to get a handle on just how bad things were, I pulled the rockers off and took out the pushrods. None appeared to be bent. and the valve springs still seem solidly mounted.

Even with the timing chain disconnected from the cam/crank sprockets, and the pushrods/rockers out, I can only turn the crank a small distance in each direction before I hear a thunk and can't turn the crank any further.

What did we break?? Any help or insight wouldl be greatly appreciated.

I feel sick at the thought of having my baby towed to the dealer in pieces with my tail between my legs (not to mention facing the "how much is this going to cost" look from my wife)...

DERTY

Stupid questions, did you pull the spark plugs while cranking the motor over? With the timing chain off and the rockers still on the push rods and lifters you probably crushed a valve or collapsed a lifter. At the very least I'd pull the heads and inspect each of those. Another question, when you heard the clunk, did the cam rotate itself? I'm curious if the piston pushing on the valve may have actually clunked when the pressure built up by the piston on the valve was high enough for the lifter to roll over the lobe. That would have made some interesting noise.

More than likely I think you chunked something under the head and I would pull it regardless. It's easy to do, you'll need some new bolts and depending on what gaskets you have you might need those as well. Should be something you can do on a Friday night and Saturday.

Just some random thoughts.

Retsik

Thanks for the fast reply!

Interesting thought... Since the cam isn't spinning with timing chain removed (and the pushrods/rockers now out), would a messed up lifter or valve actually keep the crank from turning?

DERTY

The crank will now turn, however if you chunked off a valve (not the whole thing, but a corner for example) you will be ramming that up into the head on the upstroke. That wouldn't be good! I'm not sure how likely that would occur, but you could see if you can get a lighted boroscope and use a spring compressor to open the intake or exhaust valves to check them all out. You can even snake past the valves with some of them (the high dollar ones) and look in the bores. You won't be able to confirm that you broke a lifter though.

Jabroni

You mentioned another dot on the crank sprocket. Are you using a double roller timing set or stock? An issue that sometimes comes up with double rollers is using the wrong dot for timing reference and then scrambling everything on start-up. Prepare yourself...this could be messy.

CAT3

iTrader: (9)

Well, if you lok under the covers and all the pushrod are accoutned for, then look to see if all the valves are up. When/if you find one not up, that wherein will lie the problem.

sorry tohear this happen. Good-luck and post back any findings.

Retsik

I have the pushrods out now, and all appear to be fine (no bends or crush marks that I can see). The valves all appear to be up as well...

I'm feeling ill...

BTW - It's the stock timing chain/sprockets...

Any other ideas anybody?

2xLS1

iTrader: (25)

Lay a straight edge across all the valves. Check very close of any valves are down. Since you tried to start the car, they could all be bent the same amount. Try and pressureize the cylinders with air like you would do changing the springs. If you hear air leaking through the ports, you have bent valves. It's a little late for this tip, but before you pull a cam gear and cam, put the cam gear dot at 6:00 and mark the crank sprocket with a dab of white paint. That dot on the crank gear is hard to see. There is only one dot on stock crank gears. I never move the crank once the cam gear comes off and the new cam and gear go back on. I guess this only applies if you are not changing the gears and chain.

SScam68

iTrader: (20)

Best bet is to pull the heads.

Brains

iTrader: (7)

If it were my motor, the heads would come off just to make sure.. Get the bolts and gaskets from one of our sponsors, they're not expensive at all. Once the heads are off you can see what damage occurred.

2000RATA

Pull off all the rocker arms. See then if any of the springs are still compressed. (Someone is reading this thinking I'm crazy) I have had heads come to me where the customer installed the cam wrong and broke/bent the valves. If it's the same thing the bent valves will be compressed and you'll see it fast by the springs being compressed.

CAT3

iTrader: (9)

This would be one sleepless night for me. Did you check for all valves up as recommended with a straightedge? Are they all up? If no, theres you r problem. If they are all up, then fill cylinder by cylinder with air as mentioned!

Now, how far can you move the cam/crank? If you cn get a 90* turn o it, may I suggest that you dropthe pushrods back in and check that EACH rod moves up and down?

Again good-luck, keep updated.

Larry

iTrader: (4)

If you had the rockers on while turning the engine crank then you had piston to valve interference when turning the crank without the chain installed.

I would make sure the cam is installed correctly and then run a leak down and/or compression check before I took the heads off. If you bent a valve it will show up on a leak down test.

Camaroholic

iTrader: (1)

When a friend of mine did the exact same thing (with the exact same cam), we found that he bent the intake valves on 3 cylinders on one head by doing a compression test. No compression in those 3 cylinders, all the rest looked good. Only one head had to come off, and he just replaced those 3 valves. All was well. Don't panic, just some extra work.

So DO THE COMPRESSION TEST before you start tearing stuff apart. You don't want to disassemble more than necessary.

-Andrew

dug

iTrader: (10)

I feel for you man. Sounds likely that some valves got bent. Time to get the heads ported with some bigger valves while youre at it.

Good luck

Visceral

iTrader: (1)

so you've got like 14 different answers here ;-)

*I* would start off with the straight edge method. With the rockers off, lay a straight edge over the valve tops. any more than a 1/2mm below the ruler or edge is bent. Then run a the pressurized air around from cyl to cyl and see if one or more sound really different. Rockers are off so valves are closed, and you should only hear the tiniest amount of air escaping. Look for a difference between cyls. That should tell you if you bent a valve. If you have... its nto the end of the world. Any head-porting sponsor on here should be able to give you a pretty reasonable price for replacing valves. They have alot of extra stock valves laying around, I think ;-)

Chris

Retsik

Here's the scoop as of this morning:

You all hit the nail on the head with the bent valves (and the sleepless night)... I put a straight edge across the tips of the valves and there are several on both sides that are down slightly. One or two are about 1/4" down, and a couple of others are maybe 1/16" down. I lost count of the number (nausea set it at this point ).

I'll also double-check the pushrods to see if they go up and down when the cam is spun.

Looks like I'll be pulling the heads after all...

Right now I'm wondering if I may have screwed up a piston or two (or worse, something like the crank or connecting rods). Any ideas on the likelihood of this?

In any event, my wife has been super so far. She knows this is my baby, and hasn't hounded me about the cost and time spent wrenching. I'll definitely be planning something special to let her know that I appreciate everything she's done (and not said )

Thanks for all the help everybody, It's appreciated more than I can say. I'll send updates of my progress -

Raughammer

Whoa man... stop the madness.

First thing first.... do a compression test.

Make sure you have compression... if no compression your got probs and the heads have to come off.... you got compression and it turns with no probs? You are prob good, but before you go ripping off heads or spending more green... just do a compression test.

Good luck amigo.

TaTommyWS6

I think the worse that would happen is the tops of the pistons may be a little scored up. The car never ran, only cranked over, so you could probably get away with cleaning up the top of the pistons with a little sand paper (while the piston is completely topped out in it's bore)

I don't think there is any danger of screwing up rods or anything.

Someone else can chime in if they think this is not accurate...

Tommy

Cal

iTrader: (1)

OK I'm just about done installing the same cam, and I'm wondering about this two-dot thing . . . did you ever figure out if what you saw was really a second dot, or was it just some kind of "artifact" on the gear?