The 'E' Type Forum

Hi, I am restoring a 1967 4.2 E type roadster (OTS) series 1.5 but unfortunately it is not a matching numbers car. The engine number in the car is 7L 90370-L which is clearly a low compression unit and I think it comes from a circa 1973 XJ6 4.2 as far as I can establish. The cylinder head on it is junk as it has all sorts of emission control stuff drilled into it from the top of the head into the exhaust ports.

I have manged to source a period E Type cylinder Head but without any cams. Now the question....

The cams on the XJ6 engine are like brand new, not even the tiniest mark and it seems a shame to get them re-profiled if this isn't necessary. So can anyone tell me if these cams are the same as an E Types or will they give me a very calm and sedate engine? I'm definitely not building a race car, but I would like the performance you would expect from an E Type.

Next question... would it be ok to fit the valves and buckets (which also look literally brand new) into the E Type cylinder head once it has been re-engineering with new guides and the valves re-seated. I wouldn't be asking this question if they were the least bit worn.

I will of course be fitting high compression pistons as part of this rebuild but are there any other significant problems I should be aware of?

Thank you for your help and guidance. I have to say that this forum is a fantastic resource for us amateur restorers...... but I cant find anything relevant to this specific inquiry.

Thank you for your help.

Steve

Steve, I have the head and cams from a S3 XJ6 4.2 engine on mine.
The cams have a slightly higher/larger lift, need the 12-14 thou tappet clearance and there is a larger inlet valve on the head. But your E Type head will be the smaller, standard size valves IIRC.
Get the right bits and pieces to fit and it should work.

Geoff

Thanks Geoff, unfortunately I don't think it was a series 3 XJ6. The inlet valves are the same at 1.75" the exhausts are the same diameter too.

Regards

Steve

Hi Steve....Send a PM to Peter Crespin one of our forum members......im sure he will tell you what you need to know... Steve

Hello Steve!

I’m not an expert but the main diffrecenses is probably that the inlet cam don’t have the rew counter adapter thread at the end and that they are 4 bolted to the front sprockets compared to E-type 2 bolt.
Also if someone else can confirm that the xj6 cams have a slightly different profile to provide a smother/quiet lift but still the same lift height
There is probably someone that knows this a lot better than me.
/Johan

Thanks Johan, yes they are 4 bolted cams. I've seen threads on this and the issues, which I think will be ok. My concern is performance v a regular E Type cam.

I Will pm Peter Crespin in case he missed my post. Thanks for the lead!

Regards

Steve

The cams from any XJ are perfectly suitable for use on an E. There is no difference in duration or overlap or lift and they will make absolutely no difference to the power output . The only difference in setup is that if they are the later parabolic cams ( which they sound to be ) you will need to set them up with clearance of between 12 and 14 thou . Your present head also has no influence on CR even though it is marked with a low compression . The CR is determined purely by the pistons fitted, and also have you considered just plugging up the air passages to the exhaust ports

This is what you need to read:

http://www.georgiajag.com/Documents/Camshafts.html

Its all in there.

Carsten

Christopher and Carsten have given you the information you need.
I didn't make it clear in my first post that the XJ6 cam was originally fitted to my standard E Type head before I changed to the XJ6 head. Some people even have larger valves in their standard head if new guides are being fitted. Benefit? As Christopher says, none, but some people feel the engine breaths easier.

Who is doing the engine work? You might wish to get some advice for and against various workshops via pm.
CMES at Bracknell get good reviews, there are others who used to be respected that have gone downhill.

Geoff

Thank you to everyone for your replies. they answered my questions perfectly and the links were very useful too.

Much appreciated! I have quite a few photo's of the bodywork progress so far that I need to post here as comments are always useful - new inner and outer sills, repair panels in the usual places and a new boot floor, all done at home. it looks really good and I am pleased so far, still a long way to go. The bonnet is next to be fitted. This came from a different car so doubtless this will give me some fun and games!

I needed a change from bodywork for a bit, - hence the engine questions, but I thought I could get these to the machine shop so they can crack on and hopefully it will save a month at the end of the rebuild - although it wont be next season so there is no rush.

Best regards and thanks!

Steve