I just got the timing cover off, and i can push one side of the chain about an inch in. That seems awfully loose to me. Also, if the mark on the cam sprocket is at the top of the engine instead of down aligned with the crank, that would indicate that i'm 180* out correct?

Thanks to those of you that responded to the balancer post, i got it off with wd40 and a little tapping on the sides with a hammer. Heres a pic to show where the marks on the sprockets are:

 

All I know is the chain is not supposed to be that loose. I had to change the chain on my Beretta once that had 3/4 inch play. The new one was tighter than.......

 

How many miles are on the chain?

 

Those double rollers stretch QUICK if not lubed properly on break-in. With all those links, just imagine the effect of .001" slop at each pin. That adds up quick to give a big increase in overall length. From what I've seen, this is typical wear with a common low dollar roller chain (at least on motors I've had apart). If it concerns you, replace it. Timing sets are cheap.

 

That does sound like excessive slack. As cheap as they are, just replace it, and worry no more.

Virtually all aftermarket sets are marked as yours is. It's impossible to install it "180° out". Whenever the crank timing mark is straight up, #1 (and #6) is at TDC; that happens twice during one cam revolution, but only one of those is #1 firing. The other instance of #1 TDC is when the #1 exhaust valve is just closing, and its intake is just opening, and that is also #6 firing.

So, just change the timing set, put it back exactly as it is now which is #1 firing, and you're good to go.

I'd put a good quality Link-Belt style chain back in there, or a true roller. That would be a $70 roller set, not a $20 "truck roller" which isn't a roller at all, it's bushings. Those are an inferior product to the normal "car" Link-Belt chain.

 

i already have a TRUE dual roller sitting in the garage, i was just wondering if this one had stretched.

The reason i needed to know about the timing marks is because i'm getting ready to swap cams (hence the dissassembly). In the directions it says that the the timing marks should be right next to each other- that is the cam mark should be at it's very bottom point, and the crank mark should be at it's very top point. This is why i assumed the motor was 180* out. (the mark is rotated 180 degrees)

I'm pretty sure i need those marks to line up right before i do the cam. But maybe i'm wrong, it's not like it hasn't happened before

oh BTW, the chain has about 30k on it.

Eric

 

The motor can't possibly be 180° out... rotate the exactly crank one full revolution, and the marks will be aligned. It just won't be #1 firing, it will be #6 firing, just like every other aftermarket timing set. So, the easiest way to deal with that, is to assemble the motor with the marks together, which will put the cam at #6 firing; then rotate it one full crank revolution, which will put it at #1 firing with the marks like you see them.

 

Very true. The $20 ones typically stretch like that in few miles.

 

Hang on a second!!!!!

The standard timing chains will be loose on one side while the other side is tight. I rebuilt an engine for a friend of mine a couple weeks ago and I had him pick-up a standard timing chain. He brought it over and I installed it and we both noticed the slack on one side. Now remember, this is a brand new timing set. I contacted the machine shop and asked them if it was common, plus I talked to my tech guys here at Summit, and it's normal. When you install your double roller timing chain you won't have any slack on either side. Don't ask me why, but that's how they are. As for the timing marks, yes you are 180 degrees out. The cam sprocket mark should be at the bottom and the crank sprocket mark should be at the top. Did you try to fire the engine with it that way? if so, is that why you are changing the cam?

 

i think were all not understanding one another here. I have not taken the timing chain off since the engine was running. When i took the balancer off i made sure the mark on it was at 0 degrees, or what i thought was TDC. When i took the timing cover off i expected the marks to be aligned, but instead the cam was 180* rotated, hence i was NOT at TDC, but 180* out. I'm gonna rotate the thing back around again and install the new cam, timing chain and lifters...


Now correct me if i'm wrong here, but rotating the crank one full rotation SHOULD bring the engine to TDC...correct?

Eric

 

Yes. It is at #1 TDC now, and if you rotate the crank 1 full revolution, it will be at #1 TDC again. It is at #1 firing now, but after you rotate the crank one revolution, it will be at #6 firing with the marks together. But it's easier to line up the marks with it at #6 firing (#1 TDC, #6 TDC, marks together) than it is to line them up at #1 firing (again #1 TDC, and also #6 TDC, but marks like they are now.)

The gear will only go on the cam one way. The crank gear only goes on the crank one way. So it's impossible by definiton to put the motor together 180° out of time. Since the cam rotates only once for every 2 crank revolutions, the cam position is what determines whether the particular instance of #1 TDC that the motor happens to be at, is #1 firing or #6 firing. The crank & pistons do not care.

 

excellent. Thats exactly what i needed to know. Thanks for the second time today RB...

Eric

 

Yes, to reiterate in case someone didn't pick it out of the noise:

Dot-to-dot is TDC for the #6 cyl. Both dots how YOU have it is TDC for #1.

 

By comparison......

I tore into a motor for a cam swap recently and it had a GOOD GMPP double roller set in it that had been properly pre-lubed before install/startup (I know becuase I did it). After 15K miles it had basically NO slop in it. Not like a guitar string, but pretty close. Both sides.

Compare that with your typical $20 stock replacement double-row truck chain and they will flop around like crazy (not as bad as yours, though) in only 2-3K miles.

The difference between a $20 chain and a $65 one is amazing.

 

Only reason I can think for a new chain to be at all loose (other than being defective) is if the block mains have been align bored.

 

When i saw how sloppy it was, this was first thing that came to mind. I guess i'll know for sure when i go to put the new chain on. If theres still some play in a brand new chain then the block must have been align bored. If this is the case, is there a remedy for this? a slightly smaller chain maybe?

Eric

 

Measure the center distance of the sprockets, then call Comp Cams for a custom set. Get out your wallet....

 

There are sets made for some common increments of align-boring... but the distances involved are so small, it's probably not worth fooling with on a street car.

Think about it... your chain has slack that you're measuring in inches, and align-boring moves the crank a few .001"s. By the time your motor has 1000 miles on it, the wear and stretch that will have occurred, will be an order of magnitude greater than the little tweak you just shelled out $$$$$$$ for. Don't bother.

 

Before you go and buy a high dollar timing chain, bolt on the double roller and see what kind of slack you have. If you still have slack after installing the double roller, then you should start worrying and saving your money. I'm concerned that we're getting too involved with the negative before you try the other part. It's hard for us to diagnose or give suggestion when we aren't there to see for ourselves. Try it and let us know the outcome, it should only take a couple minutes to install.

 

just bolted up the new roller. There is still slack, but not as much. I'd say prolly 1/4, maybe 1/3 inch tops. Still not as tight as i'd of liked it to be, but it's good enough for me...

i also got my old cam out, and it's extremely apparent now as to why the car felt so slow... The lobe on #4 intake is no longer a lobe, it's a circle. I put the new cam in (way easier than i thought it was gonna be, i don't understand why anyone stresses over it). Now i just gotta install and adjust the rockers and valvetrain is done. Then onto the T-56 This thing is gonna fly when it's all back together.....

Eric

 

Guess we should have said that a worn cam bearing can also contribute to chain slack.