Where can I get double overhead cam timing?

It didn’t for this engine because all the figures were known, but for a new build with a re-ground cam and shaved head it could require a lot of adjustment. It can get complicated so if you’d like it done properly, call Peter Larner Engines on (03) 9439 8986 or go to www.larnerengines.com.au.

What happens if your valve timing is not right?

Bad things can happen inside your engine when your valve timing isn’t right! This bent valve would have dented the budget. There are a couple of fundamental ways to match the position of the camshaft to the position of the engine internals during the building of a DOHC engine. The first, and simplest, is to determine lift at top dead centre (TDC).

Can a Ford 3.5L DuraTec timing system fail?

Failure to manually activate the secondary tensioner (s) can lead to catastrophic engine failure. Once the tensioners are activated there is no way to deactivate them. Once installed, the clips are removed, and when ready, the tensioners must be compressed to activate. Once the tensioners are activated there is no way to deactivate them.

When to use lobe centreline or lift at TDC?

With the lift at TDC method, the lift figure is specified, not crankshaft degrees (apart from setting the engine to TDC). The lobe centreline method can be considered to be an opposite approach because the position of the crankshaft is specified when the camshaft is at maximum lift and the valve is fully open.

What should the cam timing be on a DOHC engine?

If the cam timing was set to this smaller/narrower 110.5 degree lobe separation angle, the engine would behave much differently than the 113.5 degree lobe separation angle.

How do I set the intake cam timing?

If you wish to set the intake cam timing to the cam manufacturer’s specified value, an adjustable cam sprocket will allow you to dial in the camshaft timing to the manufacturer’s specification. 12. After adjustments are made to cam timing via cam sprockets, repeat steps 2 through 10 until the cam is “Zeroed” properly.

What happens if your camshaft timing is not correct?

If you answered “yes” to any of those questions, your camshaft timing may not be what the camshaft manufacturer specified. Improper cam timing can lead to reduced performance, increased fuel consumption and an increased likelihood of detonation.

Where does the timing belt go on a double overhead cam?

Turn the cams until the marks on the drive sprockets (commonly referred to as gears) line up and then fit the timing belt. Timing belts are often directional and will usually be marked as such. The exact configuration of timing marks depends on your engine. The variety of systems devised over the years is vast.

How did double overhead cam timing get its name?

It’s named after its designer and builder, Brian Hart, who worked at the famous Cosworth company in the ’60s. He left Cosworth in 1969 to set up his own company and made engines for various racing classes including F2 and even supplied F1 engines for a number of teams into the ’90s.

If the cam timing was set to this smaller/narrower 110.5 degree lobe separation angle, the engine would behave much differently than the 113.5 degree lobe separation angle.

How do you set up double overhead cams?

The lobe centreline method of setting up cams is as follows: After the engine is together and the cams in place and torqued down with the correct clearances, set the engine to TDC as discussed. Mount a dial indicator on the number one inlet bucket follower with the base circle of the lobe on the bucket.

How are the clearances of double overhead cams determined?

Different thickness shims are available to adjust clearances and the method is to measure the thickness of the shims with a micrometer before they’re fitted. Then the cams are fitted and torqued down and various thickness feeler gauges inserted to determine clearances.

What kind of camshafts are used in a DOHC engine?

We’ve previously described how to fit and adjust various types of camshafts and associated valvetrain components, so this time we wanted to look at double-overhead camshafts (DOHC). We noticed this classic Hart engine being assembled in Peter Larner’s race engine workshop the other day and figured it was the engine on which to show the procedure.

Where can I get double overhead cam timing?