Installing a Mopar timing chain tensioner

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robertodonnell

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Hi All,

After reading nothing but good things, I decided to order the MP tensioner for SB Mopars, and I just wanted to check the opinion on how hard it should be to install the timing chain and gears with this installed.

Even with the lock pin in place on the tensioner's chain runner, I found I had to press back on the runner to have it clear the chain so I could fit the gearset. Is this OK? I figured that it probably is, but just wanted to check. It was nearly a 2 person job to do it. Well, me and my 4 year old boy anyway!

Gearset is a Comp 3 keyway double row unit. Oh, and when I wind the crank over by hand it doesn't bind.

Your responses are appreciated, I want to fit this engine over the weekend.

Regards,

Robert
 
I tried using one with a double roller and couldn't get it to fit right. It was too tight so I took it out and didn't use it. Double roller chains will not stretch like a link type will.
 
Double rollers do indeed stretch. You just have to play around with it. The pin really doesn't hold it back quite far enough. I pressed mine back with my thumbs and it went on. It fits really tight because that's how it's designed. It's supposed to take up slack and tighten the chain, so it'll be a little bit challenging to install.
 

Too tight cant be good for the bearings or sprockets and chain. To go back in at 20K miles and install the tensioner might be a better plan.
 
robertodonnell said:
With all the load from the valvetrain weighting down on the cam, I can't see the force of the tensioner on the bearings amounting to much?
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Force from the valve train isn't even considered in my concept. Lets take away everything engine related and imagine this just 2 simple rotating shafts being pulled together at only 1 end. Bearing wear and eventual shaft linear travel could result.
I'm always leary of mixmatched aftermarket parts. One mfgr might hold to the high end of machining tolerences when another is holding the center of the tolerences. All just coffee talk though. The chain will grow longer with heat too so... too many factors at play and not enough coffee
Good luck with it.
 
RedFish said:
Too tight cant be good for the bearings or sprockets and chain. To go back in at 20K miles and install the tensioner might be a better plan.
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It's not too tight installed and straight. They are tight trying to angle everything in right. If they were bad on bearings, you would have seen a rash of 3.9s with bad bearings straight from Chrysler, because they were original equipment in the little V6s. But that was not the case.
 
FWIW, I can turn the motor backwards a tad and the leading side of the chain gets a small amount of movement in it. It was hard to get the alignment right, but once square, it slid on with minimal fuss.
 
robertodonnell said:
FWIW, I can turn the motor backwards a tad and the leading side of the chain gets a small amount of movement in it. It was hard to get the alignment right, but once square, it slid on with minimal fuss.
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Puzackly.
 
StrokerScamp said:
It's not too tight installed and straight. They are tight trying to angle everything in right. If they were bad on bearings, you would have seen a rash of 3.9s with bad bearings straight from Chrysler, because they were original equipment in the little V6s. But that was not the case.
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Thats with Chryslers production sprockets and chain dimensions too. We dont even know why the tensioner was used only in V6 and not V8 builds.
 
RedFish said:
Thats with Chryslers production sprockets and chain dimensions too. We dont even know why the tensioner was used only in V6 and not V8 builds.
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It was used on V8s, too. I've torn down some original ones that had them on there.
 
I put one on my 273. I really didn't need it with a double roller set in a engine that won't see only a few thousand miles a year but I did it anyway. It went on tight but should keep the chain tight for as long as the engine is in one piece. lol
Here's a shot. tmm
 

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Well I don't really care about all the hooha. I put on on my engine and there it stays. They work well.
 
RedFish said:
Thats with Chryslers production sprockets and chain dimensions too. We dont even know why the tensioner was used only in V6 and not V8 builds.
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Lemmie throw this at you for the sake of discussion.....

What about oil pressure? Hydraulics is a serious force to overcome. I really don't think that the tensioner could ever influence the crank and or cam enough to ever increase bearing wear since there is active oil pressure between the crank and bearings and cam and bearings. You bring up an interesting point....but I really don't think it would have an effect. I could be wrong. Stranger things have happened. lol
 
got one on my 318 with a double roller timing chain. i rev the hell out of it.

2gsflso.jpg
 
The oil reduces friction and carries away heat. Mineral properlties like zinc adhere to steel and reduce steel to steel wear ( like cam lube ).
If nothing more than oil was required there wouldn't be a soft metal bearing placed between steel and cast iron. Without the bearing, when the engine stops the oil drains away, the heat soaks and the parts sieze.
My only consideration was downward force on the front cam bearing if the timing chain was too tight. I think once the engine is run the sprokets and chain will provide relief since those are the weakest links.
Again I'm not a mechanical engineer so I dont have all the answers.
Coffee is gone too. LOL
 
Coffee gone? Time to drink beer. lol

The tensioner was originally used on the V6's to quiet a noise condition in the slightly odd firing 3.9.
 
dodge freak said:
Don't need one, spend the cash on a better chain and gear set.
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Great advice, so I'll pull it and the timing set out, sell them and buy a better timing set!

While I'm at it I'll buy myself a new timing cover gasket too.

Anyway, enough with the sarcasm. I appreciate the comments from people who have used these, and the consensus seems to be that it's how it should be. There is always going to be some conjecture as to the effectiveness of an aftermarket part (even if it is from Mopar), and I can appreciate that too.

I originally decided to purchase one of these after I'd ordered the cam kit and installed it. My decision was based on info I gathered from the web, mainly from FABO.
 
The 340 / 305 engines were raced hard in the 1970's and none of the racers used one. They were building custom parts if need be but nobody ever made these. Gear to gear sets took over....8,000 rpm was the norm but some guys went higher yet

These tensioners came to be with 100,000 mile smog warranty's. This way a 90,000 mile engine the timing would be steady at 3,000 rpm.

Easiest way to see if the timing chain is loose--if no tensioner is used - the timing will rock back and forth a few degrees when you rev it up and hold the rpms while looking at it with a timing light. If the timing marks hold steady, the chain is just fine, - not stretched .

The tensioner just allows the timing to stay steady when the chain stretches so it could past the epa smog test at 95,000 miles
 
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