The Jensen Owners' Club

Awesome! From where is that photo taken?

Richie wrote:Along with a general service - oil n filters and greasing etc, assuming that my 120,000 mile 383 still has the fibre timing gears in place, I plan on replacing them with metal ones. I'll be doing the job with my retired mechanic future father in law but before getting stuck in, What's involved? Any pitfalls to be aware of? Any top tips would be appreciated.

retired mechanic future father in law.... That was a good move! Could do with one of those.

Richie wrote:Awesome! From where is that photo taken?

Unfortunately that picture was taken after having removed the intake manifold and valley pan. Not worth doing if you have no reason to remove them, I just happened to be replacing my lifters.

Here's a close-up picture of my old "plastic coated" timing gear and chain. As you can see, with NO PLASTIC left, it's obvious how badly the chain aligns and how close it must have been to slipping and destroying the valves etc...... I was VERY lucky.

Was the chain noisy, running in this condition?

No tension left: That has to make noise. But my engine ran only a few seconds when buying the car and the heaviest noise was the missing exhaust gasket.

so...the best way of seeing the gears would be via the dizzy hole with a webcam on a stick then?

AH1951 wrote:Was the chain noisy, running in this condition?

Errr, yes, particularly at start-up but then driven gently seemed OK!
OK enough that I drove it approx 50 miles from Birmingham to Appleyards in Ilkeston

Richie wrote:so...the best way of seeing the gears would be via the dizzy hole with a webcam on a stick then?

A scope camera of some description is, I believe how mine was identified.

You can just check how much slack is in the chain as an indicator if it should be replaced.
With the distributor cap removed, turn the crank backwards (counter clockwise) by hand with a socket or if a manual car, put in gear and roll (easier with sparkplugs removed) and wait for the distributor rotor to move. I usually rotate the engine so the timing mark on the damper is around 10-degrees before TDC. Now turn the crank clockwise while watching for the distributor rotor to move. If it has more than 8-degrees of slack then the timing set should be replaced.

These billet, 9-way timing chain sets from 440 Source are really nice. I have the 3-bolt versions on two of my muscle cars and the Jensen will be getting one soon.
http://store.440source.com/Billet-1-Bol ... /114-1002/" onclick="window.open(this.href);return false;

Remains from the nylon coating of the camshaft gear, retrieved from the oil pump pickup gauze.

Wow, what happened? And unexpected or was it making noise beforehand?

The engine ran very good, no strange noises.
These 383 engines (maybe earlier / later engines as well, at least around 1968) had a nylon coating on the camshaft gear. This was done to make the gear more silent I believe. After some time the nylon disintegrates. The result is that the broken off parts fall into the sump. Martin R shows a pic of his sprocket with all the plastic worn off which must have cause the engine run very badly!
I read about all this and came to the conclusion that I needed to check and while the timing cover is off, it would be wise to replace the timing gears and chain, just as a precaution. As you can see much of the nylon had worn off so the action was really needed. I hope not too much damage has already been done to the engine.

Christian wrote:That is what you'll find:

P1090024.JPG

I agree with Shaun that there will be lots of debris in the sump and the pickup. The sump-sealing will be hard to save after 40 years. And even if you manage to save it, it will be still more difficult to get that old stuff sealed properly again. So I would give the advice to pull the sump, clean sump and pickup, and then replace all the sealings (sump, shaft seal ring and timing cover seal). If you want to reuse the harmonic balancer, get the correct puller. Never pull on the outer circumference.

what pillock at GM had the dim idear of putting plastic on a drive gear wheel it was always going to fail and cause problems with the debris { no brainer }

Just letting you guys know almost every American V8 engine from this era has this type of nylon cam gear from the factory. Not just Mopars. Mine went about 20 years ago and also had to remove the oil pan to clean out the nylon pieces from the oil pump pickup. Been fine ever since.