1984 400i Timing Chain Tensioner

How many miles on your chain? The C4/400 series motors had the longest chain of any Ferrari motor and as such suffers the most from stretch. It is scheduled for replacement every 30k miles and in my exp that is about right because by then there is no adjustment left.

Loosen the lock nut and screw the adjuster in until there is no chain noise on overrun. At that point the head of the adjusting screw needs to stand proud of the locknut by 5mm or more. If not, it is time for a chain.




You live in Kona? Many years ago I lived in Hawi near Kohala. Spent all my weekends in Kona, spent a lot of money at the bar in Buzz's Steakhouse.

 

You may also want to make a new set of plastic chain guides whilst your in there (can't remember offhand what there called!)

 

The chains are replaced every 30,000 miles?

 

I'd have to check my manual, but I believe that the expected life of the chain is closer to 60,000 miles.

John

 

400i WSM #338/85 Page B41 3rd paragraph

" After 50,000 km or when the push rod is not long enough for correct tensioning, replace the chain".

 

There you go, 50,000 km is just over 30,000 miles! I stand corrected. Thanks Rifledriver!

John

 

The chain in that motor was very long and the cam drive in general was a poor design. It was one of several reasons so many of us at the time wondered why the Daytona motor was abondoned in favor of the C4 motor design. The Daytona was trouble free and bullet proof while the C4 was not.

The chains in use at the time were Reynolds double roller. All the rage at the time but have been replaced in common usage by far superior designs with greater life spans. Also remember even the Reynolds chain only aged when you were actually driving the car as opposed to a belt that gets old just sitting there.

 

Thanks for the information, very appreciated.

 

You are welcome.

I should correct myself. We knew why Ferrari chose the C4 design. It was far cheaper to produce. They chose to save themselves money instead of long term reliability and operational costs.

Sounds kinda familiar.

 

When I lived there, Hawi was not somewhere you went, it was somewhere you left. That was a long time ago, I hear it is different now.

The spring is intended to take up slack only in small amounts as the chain streches. It has a small intended operating range.

The screw adjuster can be overtightened resulting in another type of chain noise and worn out cam drive components. A little too loose is better than too tight.
If the screw is clean and turns easily you can feel when the chain is tight (it is very subtle) then it should be backed off slightly. The test I use is with a warm motor rev it hard by by hand on the linkage and listen for a chain rattle when the motor is slowing back down. I tighten the chain just until the rattle disappears. Just a little rattle is better than a too tight chain.

Also it is important to pay attention to the amount of adjusting screw left standing proud of the nut. If close to a 1/4 inch is not left sticking out when all done the chain needs replacement. That is very important.

 

The spacer piece was made in 2 different materials, either steel (late) or phenolic (early). I should think yours as late as it is should be steel. The phenolic ones broke allowing the screw to just thread up the middle of the spring doing nothing.

It cannot due to its shape become misaligned unless it was just assembled wrong.


What problem specifically are you having?

The tensioner is very simple. The screw pushes on the distance piece (they call it a cap) that pushes on the sleeve of the spring housing which in turn pushes on the tensioner pad. The spring only acts in reserve between manual tensioner adjustments.


Removing it with the motor in the car is no fun.

 

He mai

 

Rifledriver,

I know this is a very old thread, but seemed like the right spot to ask my question.

I just purchased a 1984 400i with 30,500 miles in outstanding original condition with documented history, etc... The last owner put less than 500 miles on the car in the ten years he owned it. Prior owner owned the car for 20+ years, and kept it perfect cosmetically as per documented FCA show history.

Prior owner says all he did was change oil annually even though he really never drove the car. Stored in heated garage, covered, etc...

I dont have service record from the 20+ year owners. Reached out to the family, and they are both deceased and relatives have no records.

My question is as follows:

Given that, a) the chain makes no noise currently, and b) there is about 5/8" adjustment still left on the tensioner, and c) the car is in excellent running order and seems to have been maintained to a high level throughout it's history, is it a safe assumption that the chain was replaced at the 30,000 mile mark 10 years ago?

The key for me is no chain noise at all and such a large amount of adjustment remaining as per attached photo.

Please let me know your thoughts.

Thanks,

Jason
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I'm betting that is the original chain. Look at all the bolts, most have never seen a wrench since the day they were tightened. Don't fret, most of us are running on the original chain.

 

I bet it has been changed.

If in fact there is no noise I suspect it is OK.

I worked in the dealer who imported more of those than any other and have a lot of time working on them. I have never seen a chain go in one for 30k miles that wasn't used up.

 

Hmm you really think that engine has been out huh?

 

Quesion: to adjust it, is the hex an actual lock nut? If so how do you turn the threaded rod?

 

No need to remove motor to replace the chain. It's actually not that hard.

 

Big nut is a lock nut. The screw in the middle takes an 8mm allen. In the original design it isn't hard to get to but in a 400 it takes a little doing. If there is any sag in the motor mounts it is even more of a challenge. Typically I use a piece of an 8mm allen key cut off about 1/2 or 3/8 long. Put it in the end of the screw and turn that with an 8mm wrench. Once on a while I can get an 8mm ball driver in there.

Where was you car imported too? The reason I ask is a large percentage of them were imported to California. Same with many other gray market cars like BB512's and 288's. California at the time had a law that no gray market car could be brought in without at least 10,000 miles. Lots of brand new cars came in with 10,000 miles on the odometer and paperwork.

 

Car came into Florida from German distributor AUTOEXPO GmbH. Documentation I have from Ferrari Market Letter shows it was listed for sale from 11/85 through 1986 by original owner, then Foreign Cars Italia (Ferrari Dealer in Greensboro, NC), then original owner again. Ads shows it had less than 2,000 miles in 11/85, and 3,000 in 12/86 FML ad. When first owner finally sold it, original title I have from that sale shows 4758 miles.

 

Found the actual two pages from the workshop manual for the procedure. See attached.
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