Valve Timing Correct?

[david.g.chapman]

I have just assembled my Stromberg engine with new Burton cam shaft sprockets. Where the line is on the original sprockets, "IN" and "EX" are coded in white. For the first time, I have managed to get these marks to line up with the head surface at TDC.

When I started the engine, the idle was worse than before (lumpier) and needed a tweak on the carbs to get the engine to idle at 900rpm.

The engine felt fresher on the road, with a sharper pick up at 3000rpm. I have CPL2 cams and a low compression head.

The question is, is this the real valve timing or am I one tooth out, with the Burton cam markings confusing the issue?

Dave Chapman

[david.g.chapman]

To answer my own question, Burton do not guarantee that the IN and EX marks line up with the old lines.

I will compare my old sprockets with the new ones and mark fresh lines to line up with the old sprockets.

Dave.

[rgh0]

Given possible variations after years of modifications and maintenance on head thickness and cam tunnel location, block height and crank location, crank and sprocket keyways and cams and cam sprocket location dowels you have to be lucky for the marks on the cams sprockets to line up these days on your twin cam and give you timing that is even vaguely correct.

No real substitute for a degree wheel and dial guage on the bucket and a direct check of actual cam timing and using offset dowels or vernier cam sprockets to get the timing right. Hard to do with the engine in the car I know as most degree wheels dont fit and foul the front cross member when you try to bolt them to the front of the crank pulley.

I print up degree markings on a printable CD disk. Many dot matrix printers can print to CD's to produce a useable small diameter timing wheel at zero cost. This 5 inch disk can be fitted to either a cam sprocket or crank to meausre the cam timing with the engine installed in the car.

cheers
Rohan

[david.g.chapman]

I agree 100% Rohan.

Lucky I kept the old sprockets for a quick solution.

The accurate method is on my agenda for this winter.

Dave.