Slack In Timing Chain

CRoberts91 · Jan 20, 2015

I just fully rebuilt the 4.6 3v in my 2007 mustang. Upon reassembly I used a brand new FRPP timing kit. Got the car running and tuned but when I left the shop after it sitting overnight it started clacking in the front. It was a random noise, not in time with the rest of the engine. I pulled the front timing cover off and turned the motor over by hand. I noticed my passenger side timing chain tensioner would click in and allow slack along the top guide. I figured the tensioner was just defective. So I replaced it and again it's doing the same thing. I realized it shouldnt do this while the engine is in constant rotation but it leaves me baffled as to how the bottom guide (that touches the tensioner) is tight, but I have slack up top. Made me think my timing was off but the car was running fine. Made over 500hp on the Dyno the day before this noise happened. Any help?

Dino Dino Bambino · Jan 21, 2015

CRoberts91 said:
Made over 500hp on the Dyno the day before this noise happened.

How did you make over 500hp with these basic bolt-ons?

Pypes Shorty Headers, Pypes O/R x-pipe, Summit Race Mufflers, JLT2 CAI, Bamachips 93 Race tune, Steeda Pulleys

CRoberts91 · Jan 21, 2015

That list is long outdated. Car is now a 4.8L with a Whipple.

Dino Dino Bambino · Jan 22, 2015

CRoberts91 said:
That list is long outdated. Car is now a 4.8L with a Whipple.

I see you've fixed your sig.

CRoberts91 · Jan 22, 2015

Do you have any useful input or are you just gonna continue to make small talk?

Dino Dino Bambino · Jan 23, 2015

It's not a job I've done before but is there any chance that a part might be missing, broken, or incorrectly installed?
Wish I could offer more to help.

cmann · Jan 23, 2015

Not 100% sure, but I believe these tensioners use oil pressure to apply tension to the chain assembly. Could there be an issue with oil supply to the tensioner in question, or perhaps even an issue up top with the cam phaser setup. Doubt a phaser issue would cause an overall chain tension problem though.

CRoberts91 · Jan 23, 2015

After talking on the phone to the guys at the machine shop who built the bottom end, turning the engine by hand, and watching the cams and crank for about an hour I came to this conclusion. Between the supercharger running a higher boost and having a much stiffer valve train in the heads, the guides can no longer withstand the pressure. The tensioner losing pressure allowed the guide to drop down and the cam to turn slightly, while the crank stayed in place, thus creating the slack. I ordered upgraded cast iron and steel tensioners with built in ratchets to solve the problem. Turns out the guy who tuned my car, who has a 900hp 3V and loves these engines, is running the same tensioners. Found that out from my machine shop. So the tensioners should be in tomorrow and i will update the thread then.

ForeverDrivin · Jun 14, 2023

CRoberts91 said:
After talking on the phone to the guys at the machine shop who built the bottom end, turning the engine by hand, and watching the cams and crank for about an hour I came to this conclusion. Between the supercharger running a higher boost and having a much stiffer valve train in the heads, the guides can no longer withstand the pressure. The tensioner losing pressure allowed the guide to drop down and the cam to turn slightly, while the crank stayed in place, thus creating the slack. I ordered upgraded cast iron and steel tensioners with built in ratchets to solve the problem. Turns out the guy who tuned my car, who has a 900hp 3V and loves these engines, is running the same tensioners. Found that out from my machine shop. So the tensioners should be in tomorrow and i will update the thread then.

Very late reply, but I hope you solved your issue! Assuming so with the dead thread. I recently did upgraded valve springs on a coyote and was greated with the same chain slack/slap on startup, even with new cloyes timing parts.

I'm throwing in Ford Performance's kit with the Boss 302 ratcheting tensioners. You'd think this would be more widespread knowledge that people could pass around, about upgraded valve springs needing racheting tensioners. But I suppose most people building a motor buy both without thinking twice!

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