WATCH: Removing Slack In A-Series Engine Timing Chains
If you've got too much slack in your A-Series engine timing chain, Mini Mania now has
Rollmaster timing gear sets in stock to take up that slack!
Get Them Here
Hi guys it's Brendan from Spridget Mania. And today I'm going talk to you about having slack in your timing chain and possible cure for that.
Take a look at this in line that we have right here this 1275 in line. Now this engine as you can see it's got a few years on it and you'll notice if you look up here in this area here it doesn't have the original engine tag on it doesn't have the original engine plate. We see that and we almost always know that this block at some point has been rebuilt because of course they usually surface that top deck and they obliterate the engine tag they have to pull the engine tag off when they do that so generally that's a sign that this one has been around for a while and it's been rebuilt at some point. May also have been line bored and one of the ways that you can check for that or just check for a stretched chain or a tired chain or worn out timing gears is all of this play that you get in the chain here.
This, you know, a little bit of slack is perfectly okay, this is you know this is a pretty decent amount of slack it's not the worst you're going to see but it's a lot and if you want to eliminate that what you can do is you can actually install some timing gears and a chain that are oversized to make up for this distance that gets closer together as you line bore because of course as you line bore the crank is eventually going to sort of migrate its way towards the bore where your camshaft is so as this distance gets shorter of course that means that the stretch of the chain is going to slacken. And so we actually have some timing chain kits that can cure that problem.
So we've got a block here, actually that we're about to send out to the machine shop and just so you guys get a idea of what you're talking about so here you've got the bottom of the block you got your three main caps right here looking at this one in the front of course this is where the crank is and that of course is where your camshaft is, and of course if if the line bore is done correctly the material that's going to be removed is going to be from this area right here it's going to be removed from the cap itself and it's going to be removed from this flat so they're going to take the material away from this flat area here and they're going to resurface that and then of course all they're going to do then is just retrue. You know this area here to give you back your circle. The problem is of course is that if it's not done correctly and you're removing too much material from up here in this area instead of just sort of touching it then the distance from here to here gets slightly shorter so that can actually you know that's where you can get a little bit of a slack added slack that doesn't just come from chain stretch or other things of course, a tired motor, worn-out gears and a worn-out chain. You're going to get slack that'll happen on any motor but that's just to give you an idea of what happens when you do the line bore if it's done right you really shouldn't add any distance between the two of them but if it's not done right it can shorten the distance between the two of them and add slack.
All right let's show you what it looks like when you're building an engine, and you have a little bit of slack. All right so this is actually a 1098 that we're building you can see what the tab covers and whatnot but everything else being the same on the timing chain side and this is a brand new timing chain set and this is a freshly machine block, but you'll notice you can see all that play that you get and chain it's not terrible we've seen worse but that's a good amount and you know if you're going to rebuild an engine and you've gone to all the expense and you get to this point and you've got that much play you could live with it you know, if you're not going to race the engine or if you're not you know planning on getting crazy with it you know you could probably handle that for a street motor but it's not good and we have a fix for that.
So what we're going to do is we're going to take off this duplex chain set and we're going to go to the roll master set and we'll see how much of this slack that we can take up using the roll master set. So the roll master set as you can see looks pretty similar to a lot of the library steel sets the crank gear of course though is pre notched it's got lots of different notches so you can correct your timing which is also kind of convenient so it's oversized set but it also might eliminate the fact that you'd have to use the offset woodruff keys in your crank. So this is the one we're going to fit right now and this one is just the 20000 oversize set.
This chain is about 2000 shorter and so we're going to fit this one and see how well it goes. That chain is much tighter much tighter. That's, so that your tolerance here, you know this is really about the max amount of play that you'd want to see, maybe a little less but compared to that other set this is a huge difference. Yeah five probably would be too tight for this yeah, and then, but you can do a five and it goes all the way out to ten. So yeah, so that's the way that this is set up so this is probably what we'll end up using on this engine.
And you fit it pretty much the same way, like you said you know you've got you know when you're doing your timing when you set your timing on this you know you do have these notches that you can use also for that, with that's you know real convenient. But just taking out that slack and the chain this is an you know that this is so much better than that other set even though that other set was new. This can make a huge difference