valve clearance questions

elykat64ots · Post by **elykat64ots** » Fri Oct 02, 2015 7:21 pm

64 3.8 RA engine with stamped valve clearance of 12 intake and 14 exhaust. Any thoughts as they are greater than normal??

Gfhug · Post by **Gfhug** » Sat Oct 03, 2015 8:22 am

An early engine should be 4 thou inlet and 6 exhaust, but if it has been fitted with the later camshafts these are set at 12-14 thou both inlet and exhaust.

Looks like you'll have to identify which camshafts you have, sorry can't tell you how to identify them.

Geoff

christopher storey · Post by **christopher storey** » Sat Oct 03, 2015 8:34 am

The later parabolic cams have 4 bolt holes for the sprocket bolts. Note that it is the back of the camshaft front flange itself that you need to look at, because you can use 2 bolt sprockets with 4 bolt cams . There was also an intermediate parabolic cam used in 1968 only which had 2 bolt holes, but which can be identified by a groove on the front flange - these are rare so probably not worth worrying about. If your cams have 4 holes, then the correct clearance is 12/14 thou.

Post by **mgcjag** » Sat Oct 03, 2015 9:10 am

Just to enhance what Christopher has said have a look here for cam in info http://georgiajag.com/Documents/Camshafts.html

PeterCrespin · Post by **PeterCrespin** » Sat Oct 03, 2015 2:03 pm

mgcjag wrote:Just to enhance what Christopher has said have a look here for cam in info http://georgiajag.com/Documents/Camshafts.html

My dear Steven

One may perchance occasionally supplement what Christopher says. One may even demur from or contradict same, but one can almost never 'enhance' M'Lud's musings.

You are forgiven :-)

elykat64ots · Post by **elykat64ots** » Sat Oct 03, 2015 2:36 pm

The cam clearances are stamped on the original vin plate as 12. And 14 .
So this came from the factory and was not a later owner installed item.
I put the car on xke data site. 880108 with a photo of the vin plate. The cams have two holes on the ends.
Thanks for the reply guys I appreciate the help.

christopher storey · Post by **christopher storey** » Sat Oct 03, 2015 2:52 pm

As far as I know , no 3.8 was ever fitted with the later type of cam from the factory ( they were introduced about half way through the run of 4.2 engines in the E type c.1968 , so your data plate is very unlikely to be original, but is more likely to be a later reproduction

David Oslo · Post by **David Oslo** » Sat Oct 03, 2015 3:29 pm

Check out the pictures on xke.data. It's certainly a Tex aco plate, and from the healthy level of patina one might just think it's original.

Car looks to be a good find too!

elykat64ots · Post by **elykat64ots** » Sat Oct 03, 2015 5:05 pm

Car has not moved since 1974. The vin plate is original. All numbers match.
I have owned my 64 since 1978 and am familiar with 3. 8 and series one and have never seen valve clearances like this car

christopher storey · Post by **christopher storey** » Sat Oct 03, 2015 9:34 pm

The fact that the numbers are matching does not indicate anything at all. As I have already said, the parabolic cams were never used on 3.8 engines, and therefore the clearances prescribed would be 4 and 6 thou. The most likely thing that has happened is that at some stage late 4.2 camshafts have been substituted for the originals, and someone has made up a new dataplate ( with the "matching" numbers ) to reflect this . The only safe thing to do is to check the camshafts and see which type they are

PeterCrespin · Post by **PeterCrespin** » Sat Oct 03, 2015 10:01 pm

David Oslo wrote:Check out the pictures on xke.data. It's certainly a Tex aco plate, and from the healthy level of patina one might just think it's original.

Car looks to be a good find too!

Yes, quite amazing. I was 99% certain Christopher was correct as his response is in line with orthodoxy. Your car is so far OUT of line that had I not seen an original style ID plate I would not entertain your story for a minute. As it stands, my flabber is well and truly gasted.

Do the cams have Jag part numbers cast in and what are they? Do the flanges have a single groove machined around the circumference? Do you have the heritage certificate and does it record anything unusual?

My only thought is that in the late sixties or at some point whilst OEM data plates were still available, someone fitted parabolic cams or custom cams and to avoid mistskes bought a replacement plate and duly stamped it up. The factory settings for parabolics were in any case 12-14 for both valves.

Interesting anomaly. Try running it past JCNA and see where it gets you. Race clearances were usually 0.008" & 0.010 anyhow, depending on cam. At 12 & 14 your engine should sound like a bag of nails with non parabolics, so if it doesn't then that's another data point.

elykat64ots · Post by **elykat64ots** » Sat Oct 03, 2015 10:57 pm

Gentleman , once again thanks for the assistance. The car has been bought by an English dealer and it is heading back to England this week.

Dawnpatrol · Post by **Dawnpatrol** » Sun Oct 04, 2015 7:29 am

Assuming the data plate is original then it would suggest the original cams were competion spec, perhaps as a special order. Jaguar recommended in period if the car was used for competion the valve clearances should be increased.
The engine could have been fitted with production D-type cams, there were a few versions, I have heard of this.
Is there a large gap between the built and despatch dates on the heritage certificate.
LWE's with 15/32nd lift cams (wide angle heads only), have clearances of 11/15. These were the hottest Jaguar produced for the XK engine, only two cars left the factory with them fitted, Jaguar went to great lengths to hold on to them and are very rare.
Check the valve lift, if you have 7/16th, then you have competion cams, check for an XK part number which could be stamped or cast in.

Post by **Heuer** » Sun Oct 04, 2015 10:56 am

Having looked at a many commission plates that one is, without doubt, Factory original because the stamped characters are not in line, the shape of the '1' and the fact they used the same punch for the '6' and '9'. I agree with the theory about competition cams.

Dawnpatrol · Post by **Dawnpatrol** » Sun Oct 04, 2015 1:49 pm

On the subject of Data plates, does anybody have the definitive answer as to when the TEX ACO type appeared?
No doubt there will be an overlapping period like most things Jaguar!

Also, who does the best repro plates in the UK now?
Many years ago I picked one up from Stoneleigh which was (I thought so anyway!) spot on and appeared etched with dull alloy appearance and a slightly grayer black.
Unfortunately I messed it up and have never seen one like it since to buy.
Recently had one from Texas, initially thought they were good but now not so.

If this has not been comprehensively covered elsewhere on the forum, could we have a spec list of all the features repro data plates of each type should have. It would perhaps help drive the less accurate ones from the market and save wasting people's time and money.
For starters:
Etched not printed.
TEX ACO not TEXACO.
GEAR BOX not GEARBOX.
Correct gauge sheet.

Post by **Heuer** » Sun Oct 04, 2015 2:29 pm

Already extensively covered in the 'Factory Fit' thread: viewtopic.php?p=43521&highlight=rudd#43521

elykat64ots · Post by **elykat64ots** » Tue Oct 06, 2015 1:41 am

Thank you for confirming the data plate is original. I have also seen many original plates and reproductions. I doubt that any reproductions or originals were available prior to 1972 when the owner bought this car. I have added some photos on the xkedate page but they in my opinion are inconclusive.
The heritage certificate only has 3 weeks from DOM to shipping date and there were no comments on the bottom.
Unless one of the D type experts can id these cams I would like to thank all who commented. The car should be in a container by now awaiting shipping...by slow boat...to its land of birth. !

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