Information needed on SV073 camshafts

[jonathan280]

Good afternoon all,

The 1592cc TC engine in my Sylva kit car is, apparently, fitted with Type SV073 camshafts. This information is from the engine build sheet.

The engine is old but in good shape, having been built by Swindon Race Engines in 1987 for the 750MC Kit Car Championship. This was long before my ownership.

Here are the vital statistics, again from the build sheet:

Max lift less clearance: Inlet .433" (11mm)

Timing: Inlet 42.5/77.5 Degrees; Exhaust 76/41 Degrees

Lift at TDC: Inlet .170" (4.32mm) Ex .168" (4.27mm)

My rough calculations show a 298.5 degree duration, suggesting race-orientated cams.

Can anyone tell me the camshafts' maker?

All suggestions are gratefully received.

If it's of any interest, the background to the question is that I'm tryng to diagnose some very strange results from an ignition mapping session at Northampton Motorsport last week. The dyno plots show a huge hole in the power curve, and particularly the torque curve at about 5000rpm. This is confirmed by the way the car drives as well. The NMS folks suspect the camshaft timing. See the attachments for poor photos of the plots.

Best regards..........Jonathan

[Guy Croft]

I have a feeling SV is a Kent profile number, I will check tomorrow at work. Inlet and Ex FL is 107.5 deg, nothing wrong with that, so you can completely rule out cam timing per se - assuming it has been set up right.

Can't read your power plots, all blurred, please delete and redo, thanks.

Might be an idea to publish the fuel/ignition system details, and advise the header setup and silencer.


Members! This is a nice post, but remember I do get pretty sketchy detail thrown at me in GC Q&A, don't have time to flip from one previous post to another, so background specs should always accompany tech questions to me. Photos are appreciated. I treat Q&A as work, photos often help me diagnose, but the thing can be pretty dull reading for other members without pictures, especially those who are not familiar with the things we're talking about. And when time is at a premium, it makes life easier if I don't have to call for engine detail.

GC

[Guy Croft]

Finally found it, I knew I'd seen it before somewhere.

SV073 cam profile was by Holbay Racing Engines when at Martlesham Heath, Suffolk. Don't know much about them to be honest but there is a website at:
http://www.holbay.co.uk

GC

[jonathan280]

Guy,

Many thanks. I will contact Holbay.

I'll repost the power/torque plots, but I'm without a scanner at present, hence the woolly looking mobile phone photographs.

Best regards.........Jonathan