Early 2.4 and Carerra Tensioner Update

[tharbert]

I received my parts today to finish up the Carerra Tensioner update on my early 2.4. The new timing chain covers with mods for an air pump are giving me fits (and lining the pockets of our beloved parcel service.) My 1972 is pre-air pump.

Here's my old Mg cover along with it's M6x35 studs. The holes are 7mm and the cover is 12mm thick:


Here's the new Carerra Al cover with the more robust 9mm holes and M8x76 studs. The housing appears to be 30mm thick:


My first problem is that I didn't figure out that I had two different sized studs. As soon as I saw the new studs, I knew I was in trouble. Can I stick with M6 studs to avoid the machine shop? Are the 9mm holes an issue? What to do? A link to a previously explained elegant solution? Search turned up nothing....

Tom

[MikeDL]

I did this last weekend on my 2.4. The new cover holes are the same diameter as the old cover holes. Thicker mounting locations for top two studs on the left cover required replacement of those studs with longer (but same diameter) ones from the kit.

[tharbert]

The two air pump holes on my new cover are definitely larger to accomodate the M8 vs M6 stud. The M8 studs fit in only those two holes. And my Pelican sourced kit came with no extra studs.

Is there an issue using M6 studs in the 9mm holes in the cover with a oversized steel washer to distribute the pull of the nut across the span of the hole?

[R_Builder]

I found this thread doing a search to see how others handled this issue and thought a plausible solution was worth posting. I just completed adding Carrera Tensioners to my 2.4L engine...

To button things up nicely on the LHS chain cover, I purchased two longer M6 studs from McMaster-Carr (p/n 98867A265). They are 47.5mm long overall, with a 6.25mm long thread and a 18mm long thread. I was hesitant about the 6.25mm thread being so short, but since it was 1d, I figured it should take the torque (72 in-lbs) without stripping out of the chain housing. Here are the studs:



I used red loctite on the 6.25mm end and threaded them all the way into the chain housing, then used a large OD steel washer with the regular 6mm sealing rings and lock nuts. Looks pretty sanitary to me...



I guess the real proof of this method would come down the road when it is time to pull the chain covers again for some reason... just have to see if the loctite holds when you back off the nuts. I am hoping to not pull these covers for quite some time!

Hope this helps someone out.

[Matt Smith]

Hi
Did this mod several years ago on my 2.4 because I had a nasty clatter. Turned out to be just the ramps but I did the pressure tensioners anyway because that's 'what you did'. On reflection, and after reading a gazillion posts I doubt I'd do it again.
My original tensioners had the hydrastops (? spelling from memory) on anyway, so I needn't have worried about the noise, just pulled the covers and fixed the ramps.
Since then I"ve always had probs. Striped & cleaned the carrera tensioners many times & tried all the tricks. Now I've got stretched chains....