Camshaft timing ???

[Petter Hval]

I have just found some notes regarding the canshaft timing onmy S4 big valve head made after an engine restoration 3 years ago,and wonder if I should retime the camshafts?
The camshafts are reground to TT 36 spec. and the seat to seat valve lift are 9,68 mm (inlet), valve clearances 0,15/0,25 mm,timing figures 35/85 - 79/41 dgr. and inlet timing @ full lift 115 dgr. The engine havea flat spot from 2400 - 3100 rpm. brobably an carb. issue ?? I`m planing to get some adjustable verniers for the cams, and open for any suggestion how to set the timing.
Petter






















































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[ppnelan]

...any suggestion how to set the timing.

Very carefully...
Getting the timing right on an engine with a 'peaky' camshaft is critical. Get it spot on and it will purrrrr; get it wrong and it will probably still run but will be a dog... See Miles Wilkins' Twin Cam Engine book for details of how to do it.

Matthew

[dlbarnes1]

Top lobe center (full lift) for the exhaust timing works out to 109 degrees BTC.
Dave 72 Sprint DHC

[Dag-Henning]

Petter, - the flatspot is most certainly a carb issue. If I get you right ; - yor engine has been running on these cams for the last three years, and you want to check that they are timed correctly ? If so, check that the inlet cam has max lift at 115 degrees, and the ex-cam at 109. That's what your figures says. These are not what I would call "very hot cams" , so one or two degr. out, would probably not make a very big difference .....

Dag