Timing Chain RB: Too Tight?

[moparnation74]

He probably didn't "have to" pull it either, but he did. If the chain was to tight he wouldn't have got the cam back in.

This is true....but I don't rely on the simple fact it got in...So we are good...I want actual not fictional...Hence is why I would simply check the stretch...Whats the big deal it takes five minutes and as I said earlier he is probably fine...

 

[dieseldazzle]

Could be a set for align bored mains they sell them oversize.

 

[66Satellite47]

Could be a set for align bored mains they sell them oversize.

My memory may be slipping, but doesn't align boring tend to loosen timing chain fit by moving crank centerline up slightly.

 

[threewood]

My memory may be slipping, but doesn't align boring tend to loosen timing chain fit by moving crank centerline up slightly.

I have heard of this, but it could go tighter or longer. If you bore the same center axis, nothing changes. But, if you bore on the outside of the centerline of the crank it would make the timing chain tighter. Nothing on mine was align bored and the original chsin with plastic was still in it (and sloppy) .

I double checked the part number, it is correct.

 

[66Satellite47]

I have heard of this, but it could go tighter or longer. If you bore the same center axis, nothing changes. But, if you bore on the outside of the centerline of the crank it would make the timing chain tighter. Nothing on mine was align bored and the original chsin with plastic was still in it (and sloppy) .

I double checked the part number, it is correct.

Threewood, to clarify, my response was to dieseldazzle. I understand you haven't had a align bore done. I think your "tight fit" is just fine. I have had a few timing sets that required pushing the cam back out slightly and then working the cam gear & crank gear on together. They worked fine, no cam bearing damage.

 

[Garys1969RR]

I think tight is good. After a few minutes of running, it won't be as tight, and will have more and more play as time and miles go by. New ones are usually difficult to install. Everything has to be lined up perfectly. I usually put the cam in, with the top sprocket bolted on, aligned so the sprocket mark is straight down. This makes it easier to put the cam in. Then remove the top sprocket, put the #1 piston at TDC, and put the chain and sprockets on together, with the marks aligned. The alignment may still not be perfect, especially with a new chain. So I slide the assembly on, and put a cam bolt in finger tight, then rotate the crankshaft back and forth until the top cam centers on the cam dowel and the bolts align. Then I bolt it all up and double check the timing marks alignment. Good luck!

 

[threewood]

Thanks for the responses! Got the bolt today so I spun it around and didn't notice any tight spots. And as for the slack (or lack thereof), I didn't notice any while turning the crank and watching the cam gear. Seemed to move at the same time. But no valvetrain in creating any tension.

And the bolt was about 3/4" too long from Mopar so I measured the damper length and free end and took off enough to leave it short where the threads in the crank end with a hacksaw. Damper is a Summit SFI rated damper and looks beefy.

Again, appreciate the help and thanks! I'm sure I will be back as this thing is just getting going!

 

[66Satellite47]

Thanks for the responses! Got the bolt today so I spun it around and didn't notice any tight spots. And as for the slack (or lack thereof), I didn't notice any while turning the crank and watching the cam gear. Seemed to move at the same time. But no valvetrain in creating any tension.

And the bolt was about 3/4" too long from Mopar so I measured the damper length and free end and took off enough to leave it short where the threads in the crank end with a hacksaw. Damper is a Summit SFI rated damper and looks beefy.

Again, appreciate the help and thanks! I'm sure I will be back as this thing is just getting going!

Threewood, sounds good. A tight fit to start with is good. BTW stock Mopar crank bolts come in two sizes, 1 1/4" long for Big Blocks and 2 1/4" long for Small blocks. Good luck on the rest of your project.

 

[miller]

Yup! You want a somewhat 'tight' fit on the timing chain. No bad binding, but no slack, either. If you have much slack to speak of...you'll see it, checking the timing...timing will float. Whole purpose of a 'tight' chain, is to keep the timing steady...in one place.

 

[threewood]

Yup! You want a somewhat 'tight' fit on the timing chain. No bad binding, but no slack, either. If you have much slack to speak of...you'll see it, checking the timing...timing will float. Whole purpose of a 'tight' chain, is to keep the timing steady...in one place.

Great, thanks! One trick I have done on my sb 318 was to add a set collar to the distributor shaft so the intermediate gear cannot walk up. There wasn't a whole lot of play but enough to see the timing move a couple of degrees.

The original chain had slack 360 degrees. I could grab it at any point and pull it away from the sprockets a good deal, aluminum cam gear was worn and plastic coated chain was in sorry shape. This is a step in ghe right direction. Now, I have to get it degreed.