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Timing chain tensioner?

I could probably find out by contacting an old friend at JeepTech. Don't know if he would remember though. The 2.5 was developed alongside the 4.0 with the 4.0 leading the way a bit. According to him, to test the 2.5, they took a 4.0, cut the center 2 cylinders out, welded the block back together and had a crank made so they could do real life testing of it.
 
souske said:
my guess would be so that you can wind the 2.5 to the moon to make the jeep go.
Click to expand...

I dunno-- 120HP @ 5000 rpm doesn't sound like "the moon," but compared to my '88 4.0L it's pretty close....

I'd guess that the tensioner is there to quell the cam harmonics you can get at high rpm in the 4.0L engines-- nothing inherent to the 2.5L.

It would probably be a good addition to any 4.0L that will see +5000rpm.
 
Shorty said:
I'd guess that the tensioner is there to quell the cam harmonics you can get at high rpm in the 4.0L engines-- nothing inherent to the 2.5L.
Click to expand...
But it is installed on the 2.5L, not the 4.0L. The 4.0 has that stupid rubber block that throws off the timing.
It would probably be a good addition to any 4.0L that will see +5000rpm.
Click to expand...
I don't see why it wouldn't hurt on any 4.0L. Especially when the chain stretches with age.
 
Talyn said:
But it is installed on the 2.5L, not the 4.0L. The 4.0 has that stupid rubber block that throws off the timing. understood-- I can only assume that no one figured you'd be spinning a station wagon engine to +5000???

I don't see why it wouldn't hurt on any 4.0L. Especially when the chain stretches with age.give it a shot and let us know-- I have to admit I'm curious
Click to expand...
 
Talyn said:
Whats red line on the 2.5L?
Click to expand...

hell if I know-- mine's an "SE" model with every option that Chryco couldn't figure out how to remove or charge extra for and nothing else.

I know the original 2.5L (carb and throttle body) advertised peak H.P. at 5000 rpm and the multi point engine was advertised at 5200 rpm. I don't think mine (256000 mi) would ever make it past 4000 rpm without moving some of it's internal goodies to external locations:explosion
 
Shorty said:
...would ever make it past 4000 rpm without moving some of it's internal goodies to external locations:explosion
Click to expand...

Now that is sig worthy!

David Bricker / SYR
 
Talyn said:
Lol.

One though it maybe the 2.5L valve train doesn't have enough mass to keep the chain taught under low RPM conditions.
Click to expand...

I stopped questioning AMC designs when I found duct tape splices.... now I'm just curious if there's any benefit to the tensioner on a 4.0L. Not curious enough to do anything about it, mind you, but still curious.
 
I'm definitely interest in this as well. When I took apart my old block with about 180k on it I couldn't believe the amount of slop in the chain. And people wonder why they idle a little rough... Is it feasible to squeeze a 2.5 tensioner under the cover??
 
I haven't measured cover distance, but it should fit. You would just need to drill and tap two holes in the block to the passenger side of the timing chain.
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I wish I had taken a closer look at that 2.5L we had in the machine shop a month ago.
 
The six has fewer degrees between firings than the four cylinder 2.5L. The chain on the 2.5 probably is stretched and relaxed more than the 4.0 between firings and creates more noise and unwanted harmonics which require dampening?
 
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