SRD Sep 03, 2013 10:03 pm
Subject: Re: What is this part?

Tim hi

Well identified, clearly a very rare item, not one I have come across before!

randall977 Sep 02, 2013 12:07 pm
Subject: What is this part?

This part was amongst some spares which were in the boot of the Rapide when I bought it. It is aluminium, around 12" wide and appears to have been screwed to the car? I can't work out where it came from but it was probably internal...

Anyone have any idea?

TVJL Sep 03, 2013 10:52 am
Subject: Re: What is this part?

Hi Christian,

Nice find! Smiling

What you have there is quite a rare thing - it's a cam timing tool. It may (or may not) be an original factory item - these are often cut out of 1/4 inch thick alloy and will have stampings such as 'Front', 'C Type' in the centre and numbers on each limb e.g. 100 and 50. However, since these are very simple items to replicate I have come across 'workshop' items cut from different stock, such as thiner alloy and mild steel.

Regards,

Tim

randall977 Sep 04, 2013 9:04 am
Subject: Re: What is this part?

Thank you Tim, not many people would know that!

David Sep 04, 2013 1:30 pm
Subject: Re: What is this part?

Fascinating! Appears home made as asymmetrical, and it's quite hard to see which of its surfaces or edges would have been precise enough for measurement against

randall977 Sep 04, 2013 2:13 pm
Subject: Re: What is this part?

As I remember the cam sprockets are individually adjustable, this is partly to take into account the chain stretching over time resulting in the relative distance between each camshaft increasing. I think this tool must lock two cams into the correct position, then the sprockets can be loosened and the chain set to the correct tension using the top tensioner.

It also allows the cams to be adjusted relative to the crank for the timing.

ASD sell much nicer versions than my hand made one.

ray sherratt Sep 04, 2013 7:57 pm
Subject: Re: What is this part?

Having built a great meny of these engines I for one would`nt
use a cam timing jig there not accurate. The only way to time
any Aston based engine is to use DTIs

Ray Sherratt.

David Sep 05, 2013 7:58 pm
Subject: Re: What is this part?

I take it from Ray's helpful remarks that the cut-outs in the tool's underside as illustrated above in Christian's photo are intended to enable setting of the cam timing by reference to the position of the cam lobes & their profile matching the cut-outs in the tool. So I can well understand Tim's remark that other tools are more heavily constructed as being less prone to distortion. I agree entirely with Ray that the proper way to set the cam timing is with a dial indicator gauge not some technician's home-made short cut. The other facet to perhaps consider is the provenance of the tool to a specific Rapide in that there were at the time several cam profiles available (DB4, DB4GT, standard Rapide, experimental [as my other car], etc) and without a micrometer etc one cannot be sure the tool actually matches the cams installed in a particular engine.

TVJL Sep 06, 2013 5:53 pm
Subject: Re: What is this part?

I agree with all that has been said, of course. For me, these things are just nice pieces of AML 'history' to own. For reference, here are a couple of snaps taken of the factory tool in my own collection.
Attachments:
20130906_174057.jpg (Filesize: 83.56 KB)
20130906_173958.jpg (Filesize: 73.05 KB)

randall977 Sep 06, 2013 11:24 pm
Subject: Re: What is this part?

I like those - very nice!