Engine out timing chain replacement

Yep, after much thought and research, decided to pull the engine to do the chain.

Initially I first thought of doing the "wind it in" method with engine in place, that many others have chosen. But........gaskets leaking, seals........etc etc.

My car has about 42 k miles, carb'd automatic. Noticed at idle the chain making itself know by slaping the cover. Looked at the tensioner adjuster, and it was "adjusted all the way in.

So, engine out. Fabed up a stand, approached all this very carefully, not in a rush.

Getting right to it (skip info on pulling engine, cleaning etc). After removing the tensioner assy, first interesting tid bit appears. The tension rail did not pivot easily at all........uh, very little. After removing the cover, which showed evidence of chain hitting, the rail was removed and the inner pivot bushing was very tight in the rail. The bushing should be clamped by the tightened stud fastener and the rail pivots about it, being fed drip oil through two feed holes in the pivot base of the tensioner.

In the picture below you will see the original rail and bushing. What happened here is metal transfer from the softer rail to the bushing through what is called fretting. Fretting occurs under heavy load and very slight movement. Supplied lube can be displaced, and this is what can happen. Previous owner? adjusted tensioner to no avail, it wasn't moving.

Get's better, after recieving the new "updated" tensioner, you can see the additional oil feed groove on the side of the pivot bore (both sides). Test fit in the case of the new rail prompted a mic check/comparison between the old and new. New is wider, if repalcement inner bushing of same width dim is used, it will clamp the new rail, not allowing it to pivot.
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Ok, so now the real engineering kicks in. Maybe along with the update in the tensioner, the F guys modified the inner pivot bushing (NLA BTW) and machining dims in the front cover. Can't answer this.

So with a quick thermal expansion checkon the rail / housing bore, I am leaving the housing as is, making a bushing of 17-4 PH (grind/polish), adding oil supply grooves which line up with the oil supply holes (will be enlarged) on the new rail and carefully milling a bit from each side of the new tension rail at the pivot area. The original inner bushing had fairly pronounced machining grooves.

Onward!

 

So with the cover off, all innards removed, wow, that's strange..............

The tube which recieves the short hose from the water pump had very strange striated corrosion, heavy only in the id of the tube. This machined tube threads in the front cover and has a tapered end at the threaded area.

Had a new one made and allowed for hard anodizing. Hard anodizing, unlike decorative, actually penetrates the aluminum . Very effective against corrosion.

I have two extras if anyone needs one ( $85.00 ). I left mine as anodized on the exterior, but this can be painted over if desired.

Well, batteries went out in camera, will post pics when new are installed.

 

Below are the pics of the new hard anodized water tubes. Again, have two extra's @ $85.00 each.
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Also changing the oil pump chain and tensioner. Here we go again, th etensioner has been updated (Pic) along with the method of attachment. New style uses a stud, nut and washer. Initial check of line up to chain revealed the new style tensioner's wear pad would not center on the chain. Even the old style was close to the edge (see wear marks).

Resolving this was just a matter of taking the new tensioner apart and swaping over the over lap of the hinges.

Just good practice to check and double check everything!
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Fritz,

The new tensioner in the photo is an actual Ferrari part, not aftermarket. Everything so far, including gaskets, have been factory parts.

Godspeed!
Dave

 

Well the tensioner was ordered through Maranello Conessionaires, believe came in a F bag with part number. Who sells the "aftermarket" one?

Godspeed!
Dave

 

Brett,

Yea, that's neat, what a great combo. My GT4 is yellow, the 400A is black. Been enjoying your posts, gave me the guts to dive in.

Hand built is a challenge, I like it. Built several BMW F2 Schnitzer twin cam, slide throttle, mechanical injection , dry sump etc set ups, lots of hand fitting. Cool stuff also but man o man these castings and 6 DCOE carbs, love it.

Godspeed!
Dave